UNITED STATES OF AMERICA
FOOD AND DRUG ADMINISTRATION
BLOOD PRODUCTS ADVISORY COMMITTEE
THURSDAY, OCTOBER 21, 2004
This transcript has not been edited or corrected, but appears as received from the commercial transcribing service. Accordingly the Food and Drug Administration make no representation as to its accuracy.
The meeting came to order at 8:00 a.m. in the Ballroom of the Gaithersburg Holiday In,, 2 Montgomery Village Ave, Gaithersburg, MD 20877, James R. Allen, Acting Chairman, Presiding.
James R. Allen, M.D., M.P.H., Acting Chairman
Kenneth Davis, Jr. M.D., Member
Samuel H. Doppelt, M.D., Member
Harvey G. Klein, M.D., Member
Judy F. Lew, M.D., Member
Charlotte Cunningham-Rundles, M.D., Ph.D., Temporary
Jonathan C. Goldsmith, M.D., Temporary Voting Member
Liana Harvath, Ph.D., Temporary Voting Member
Blaine F. Hollinger, M.D., Temporary Voting Member
Matthew J. Kuehnert, M.D., Temporary Voting Member
Kenrad E. Nelson, M.D., Temporary Voting Member
Keith C. Quirolo, M.D., Temporary Voting Member
George B. Schreiber, Sc.D., Temporary Voting Member
Michael D. Strong, Ph.D., Non-voting Industry
Linda A. Smallwood, Ph.D., Executive Secretary
Welcome, State of Conflicts of Interests........ 3
Dr. Smallwood and Chairman Allen
Transmissible Spongiform Encephalopathies....... 9
Supplemental Testing for HIV and HCV........... 25
Open Public Hearing
Combined Statement on HIV and HCV.............. 38
Supplemental Testing from AABB, ABC and ARC
FDA's Current Thinking on Reentry of Donors
Previously Deferred for Anti-HBc Reactivity
Introduction and Background.............. 45
Overview of Serology..................... 49
Studies of Deferred Donors............... 66
Open Public Hearing - Manufacturers........... 111
Committee Discussion.......................... 115
Potential Risk of Transmission of Simian
Foamy Virus (SFV) by Blood Transfusion
Introduction and Background
Dr. Edward Tabor........................ 159
Simian Foamy Virus Epidemiology
Dr. Walid Heneine....................... 168
SFV Transmission Studies
Dr. Arifa Khan.......................... 195
Recent Research Results
Dr. James Brooks........................ 211
Dr. Peter Ganz.......................... 233
Demographics of Primate Handlers
Dr. Nicholas Lerker..................... 246
Open Public Hearing........................... 265
Open Committee Discussion..................... 270
DR. SMALLWOOD: On the record. Good morning. Welcome to the 81st meeting of the Blood Products Advisory Committee. I am Linda Smallwood, the Executive Secretary. At this time, I will read the Conflict of Interest Statement that applies to the proceedings for this meeting over two days.
This announcement is part of the public record for the Blood Products Advisory Committee Meeting on October 21, 22, 2004. Pursuant to the authority granted under the Committee charter, the Director of FDA Center for Biologic Evaluation and Research has appointed the following individuals as temporary voting members: Drs. Charlotte Cunningham-Rundles, Jonathan Goldsmith, Liana Harvath, Blaine Hollinger, Matthew Kuehnert, Kenrad Nelson, Keith Quirolo and George Schreiber.
To determine if any conflicts of interests existed, the Agency reviewed the agenda and all relevant financial interests reported by the meeting participants. The Food and Drug Administration has prepared general matter waivers for the special government employees participating in this meeting who required a waiver under Title 18, United States Code 208.
Because general topics impact on so many entities, it is not prudent to recite all potential conflicts of interests as they apply to each member. FDA acknowledges that there may be potential conflicts of interests but because of the general nature of the discussions before the Committee, these potential conflicts are mitigated.
We would like to note for the record that Dr. Michael Strong is participating in this meeting as the Non-voting Industry Representative acting on behalf of regulated industry. Dr. Strong's appointment is not subject to Title 18, United States Code 208. He is employed by the Puget-Sound Blood Center and Program and thus has a financial interest in his employer.
He also is a researcher and a speaker for a firm that could be effected by the Committee discussions. In addition in the interest of fairness, FDA is disclosing that his employer, Puget-Sound Blood Center has associations with regional hospitals and medical centers.
With regard to FDA's invited guest speakers, the Agency has determined that the services of these guest speakers are essential. There are interests that are being made public to allow meeting participants to objectively evaluate any presentation and/or comments made by the guest.
For the discussions of Topic 1 related to Reentry of Donors Previously Deferred for Anti-Hepatitis B Core Reactivity, Dr. Susan Stramer is employed by the American Red Cross.
For the discussions of Topic 2 related to The Simian Foamy Virus, Drs. James Brooks and Peter Gantz are both employed by the Biologic and Genetic Therapies Directorate, Health Products and Food Branch, Health Canada. Dr. Walid Heneine is employed by the Division of AIDS Research at the Center for Disease Control. Dr. Nicholas Lerche is employed by the California National Primate Research Center, University of California.
For discussions of Topic 3 on Deferral on Donors with Possible West Nile Virus, Dr. Michael Busch is employed by the Blood Centers of the Pacific. He has contracts and is a researcher, speaker and advisor for firms that could be effected by the discussions. Dr. Theresa Smith is employed by the National Center for Infectious Diseases, Center for Disease Control in Fort Collins, Colorado. Dr. Susan Stramer is employed by the American Red Cross.
In addition, there are regulated industry and other outside organization speakers making presentations. These speakers have financial interest associated with their employer and with other regulated firms. They were not screened for these conflicts of interests.
FDA members are aware of the need to exclude themselves from the discussions involving in specific products or firms for which they have not been screened for conflicts of interests. Their exclusion will be noted for the public record.
With respect to all other meeting participants, we ask in the interest of fairness that you state your name, affiliation and address and any current or previous financial involvement with any firm whose products you wish to comment upon. Waivers are available by written request under the Freedom of Information Act. At this time if there are any additional declarations to be made by anyone involved, please do so.
Hearing none, I will move to my next series of announcements. First, I would like to announce that Dr. Jay Epstein, the Director of the Office of Research for Blood, is delayed because of an accident on his way in. So we will proceed with the meeting. However once he arrives, we will make adjustments with respect to acknowledgment of our outgoing members.
So at this time, I would just like to make a few announcements and I will then turn the meeting over to our chairman. On the table outside, there was an announcement of a notice of the Second Annual Stakeholder Meeting on the Implementation of the Medical Device Userfee and Modernization Act. That meeting is to take place on November 18, 2004. So if you would please be advised of that and there is this copy that is out on the table.
Secondly, I would like to give you the tentative meeting dates for the Blood Products Advisory Committee for 2005. They are as follows: March 17 and 18, July 21 and 22, December 1 and 2. Again these are tentative and you will be advised in the appropriate fashion.
At this time, I would like to introduce to you the members of the Blood Products Advisory Committee. As I call your name, would you please raise your hand. For this meeting, the Acting Chairman is Dr. James Allen. Seated next to him is Dr. Liana Harvath, Dr. Kenrad Nelson, Dr. Matthew Kuehnert, Dr. Keith Quirolo, Dr. Blaine Hollinger, Dr. Jonathan Goldsmith, Dr. George Schreiber, Dr. Michael Strong, Dr. Judy Lew, Dr. Harvey Klein, Dr. Samuel Doppelt and Dr. Kenneth Davis. Dr. Allen.
ACTING CHAIRMAN ALLEN: Good morning. I would like to welcome you all to the Blood Products Advisory Committee Meeting. We have, I think, a very important agenda before us over the next two days. We'll start out with some Committee updates. I would like to remind all of the speakers please that it is important to keep to the time limits that have been assigned to you during the presentations.
Also I just would like to remind speakers that you have a diversity of backgrounds of people on the Committee. I think everybody here is expert. Together we make a remarkable committee. We do not all have expertise in all the jargon of each of the fields that are necessarily being presented. So to assist in our fully understanding what you're saying, it would be helpful as you first begin talking about a topic if you're using jargon or abbreviations or acronyms and so on, please provide explication for the Committee about that term.
We'll move forward. The first update is a summary from the meeting last week of the Transmissible Spongiform Encephalopathies Advisory Committee (TSEAC) to the FDA. Dr. Asher.
DR. ASHER: Thank you. Good morning. I'm going to present my own informal summary of part of last week's TSE Advisory Committee's meeting. With the exception of one statement that will be obvious, the rest of the talk is my own informal summary. There's a formal summary out on the table kindly prepared by Bill Freas, the Executive of the Committee. And within two weeks, we should have posted on the web the transcripts, all the Government presentation slide sets and most of the non-government presentation sets for your use.
The Committee heard five informational presentations that I won't summarize and then the sixth issues was decisional and that is one of periodic reviews of our FDA/CJD, vCJD Blood Safety Policy. The Committee was asked to reappraise the adequacy of current policies. We began with a history of FDA actions, then the recent events of concern which I'll go over in just a minute and then we had a full scientific program addressing the blood policies and then questions for the Committee. Next please.
The Committee, the formal charge was to provide advice on whether recent information regarding Variant Creutzfeld-Jakob Disease (vCJD) warrants consideration of additional safeguards for FDA regulated human blood and blood products. Next please.
Actually the history of FDA policy goes back to 1983 which was the first time that the FDA announced policy based on the assumption that human blood was likely to be similar to animal blood in that it would be infectious during both the incubation period and clinical disease of Spongiform Encephalopathies.
The first geographic based deferral policy was recommended in 1999, deferral of donors who had spent six months in the United Kingdom between the beginning of 1980, the presumptive start of the BSE outbreak there and then end of the 1996 when the U.K. had implemented a full set of strict food chain protections. Current policy was announced in January of 2002.
In December of 2003, U.K. authorities reported the first case of vCJD occurring in a small cohort of recipients of labile blood components, one of the 50 such recipients in only 15 to survive underlying disease for more than three years. In July of this year, the United Kingdom reported a second transfusion associated case.
In the same month from the U.K. came a survey of appendicle tissues from an anonymous operating room specimens and it found this as I'll show you in a few minutes a surprising high number of those tissues contained abnormal protease resistant prion protein thought to be a finding years before the onset of neurological disease.
Then finally, an issue of concern to many people in September of this year, the United Kingdom authorities notified certain recipients of plasma derivatives that they were at increased risk for variant Creutzfeld-Jakob disease.
In conjunction with that although referred to indirectly at the TSE Advisory Committee, I'd like to read to this Committee a statement from CBER. "U.K. authorities recently notified some recipients of plasma derivatives that they might be at increased risk of vCJD. These products included Coagulation Factors 8, 9 and 11 as well as Anti-Thrombin 3 and intravenous immunoglobulins. The derivatives of concern were manufactured from plasma of U.K. donors between 1980 and late in 1999 when consistent with a decision announced in 1998, U.K. manufacturers stopped using U.K. plasma. The last expiry date for any of the U.K. products was in 2001.
Some Factor 11 made from U.K. plasma was used between 1989 and 1997 to treat a relatively small number of patients participating in several investigational new drug studies in the United States. No Factor 11 product used in the United States was manufactured from a pool containing plasma from any donor known to have become ill with Variant Creutzfeld-Jakob Disease. That is there were no known implicated lots. The FDA and CDC are discussing the Factor 11 importations and assessing the risk to recipients. This assessment will be the basis for any further recommendations."
I think it's fair to say that this issue which was not on the agenda of the TSE Advisory Committee is of sufficient significance that one can expect that it will be addressed more fully in subsequent meetings of the TSE Advisory Committee. Next slide please.
I summarize in the handout current U.S. blood donor policies and there are policies regarding both donor at increased risk for conventional forms of Creutzfeld-Jakob Disease and Variant Creutzfeld-Jakob Disease. Next slide please and move on to the next slide.
There's a greater concern about Variant Creutzfeld-Jakob Disease because it's so very different from other forms of Creutzfeld-Jakob Disease, both in its neuro-pathology and in other pathology. There are accumulations of abnormal prion protein in lymphoid tissues that are not seen in other forms of Creutzfeld-Jakob Disease. Next slide please.
For that reason, we were concerned that because of this unusual involvement of lymphoid tissues there was a greater likelihood that there might be infectivity in blood. In a general way because the disease was so different in clinical presentation and in pathology, there was uncertainty about how predictive the relatively reassuring epidemiological information that suggested that if actual transmissions of conventional CJD had occurred through blood, we wondered whether we could rely on that evidence to predict the behavior of vCJD. For that reason, more strict policies were recommended. Then of course, when the U.K. authorities announced their own lack of confidence serum of U.K. origin, it had to increase our own concern. Next slide please.
There is some good news. Throughout the world, the 23 known BSE countries, the recognized cases of the disease are decreasing in most of those countries with the exception of Spain and the possibility of one other country. Next slide please.
In the U.K. where the disease peaked at tens of thousands of cases in cattle, in 1992 only 600 cases were recognized last year. Also good news, over 80,000 cows in risk groups have been tested since June by the U.S. Department of Agriculture and although the surveyance program may not be perfect, it has to be reassuring that not a single true positive brain has been detected in that survey nor have any brains been detected in a smaller survey conducted in Canada. Next slide please.
The number of cases of vCJD worldwide is smaller than some had feared at the beginning of the outbreak. One hundred and sixty cases have been recognized as of earlier this month. One hundred and forty-nine of them have been in the U.K. and three in long time residents who moved to other countries. However, seven cases in France and one case in Italy occurred in people who had never visited the United Kingdom. Next slide please.
There is also good news from the United Kingdom in that new cases of vCJD appeared to have peaked in 1999 and deaths in 2000. Next slide please.
The cases of vCJD in U.K. residents have permitted some projection about what the minimum incubation period of the disease might be. A minimum of nine to 11 years incubation is concluded from the U.S. and Canadian case.
The Irish case had a history that traveled back and forth. So it's hard to draw any conclusion from that case. The blood borne cases that I'm going to present now suggest that there's an incubation period of six years in one case and greater than five years in a second case who had not developed symptomatic disease. Next slide please.
Not such good news is a finding of an appendicle survey that was published in July of this year. This is based on the recognition at autopsy that most patient with vCJD had detectable prion protein in lymphoid tissue and then fortuitously, two of the cases had had operations on tonsils and appendix done several years before they died which demonstrated that the abnormal protein was detectable in tonsils and appendix for at least two years before death, but not ten years before death.
That was the basis of a survey of normal tonsils and appendix that I just referred to. The tonsular survey didn't turn up anything, but the appendix based survey found three positive appendices out of 12,674 adequate specimens which predicted a probable rate in the population of more than 100. Two hundred thirty-seven was their actual predication cases of incubating vCJD per million population which is somewhat discordant from the mathematically-based projections, but it certainly is of concern and shows you the uncertainty surrounding the whole situation. Next slide please.
As most of you know, the first probable transfusion transmitted case of vCJD in the U.K. was recognized last year. A clinically healthy blood donor became ill with vCJD three years after the donation and a recipient became demented and died with vCJD three years after that. Next slide please.
The second case was reported in July of this year. The donor became ill 18 months after donating whole blood in 1999. Both these recipients by the way received non-leukoreduced red blood cell concentrates. The recipient died of a ruptured aortic aneurism without any history of dementia. It's interesting that the tonsils and appendix of that recipient were normal but abnormal prion protein was present in several areas of the spleen and in cervical lymph node. There was really very little doubt that the recipient was incubating Creutzfeld-Jakob Disease and judging from the behavior of these infections in animals, one would think that within a couple of years the patient would probably have come down, the infection would have entered the central nervous system, the patient would have come down with Creutzfeld-Jakob Disease.
One unfortunate interesting observation of this patient, this is the first patient studied found to be heterozygous for methionine and valine at Codon 129 of the prion protein and coding gene. The heterozygous genotype is known to be somewhat but not completely protective against other forms of Creutzfeld-Jakob Disease, Sporadaica Creutzfeld-Jakob Disease, Iatrogenic Creutzfeld-Jakob Disease and some had hoped that it would be completely protective against Variant Creutzfeld-Jakob Disease. Clearly, that is not the case. Next slide please.
So the implications for public health of these findings I've listed here. CJD was transmitted by transfusion. I think the only logical, the chances that these are two fortuitous dietary acquired cases occurring in a cohort of 15 people who survived for more than three years is less than one in a billion. So I think the only logical conclusion is that these were transfusion transmitted cases. Although there's nothing like genotyping that one can do to establish the connection at a molecular level.
The prion protein, methioline and valine 129 genotype did not convey absolute resistance to infection at least after adaptation to humans and intravenous exposure. A second wave of vCJD cases in heterozygous individuals is possible, possibly smaller than the first wave and of unknown magnitude. That's because 50 percent of the U.K. population is heterozygous for that gene, for methioline and valine at that gene.
A recent survey of prion protein in appendix predicted a rate of 237 infected people per million in the U.K. That has to be considered a minimum rate if it's confirmed. A number of persons in the U.K. and other BSE countries potentially have vCJD in their blood and that can be present for at least three years prior to the onset of clinical disease. For that reason, we continue to believe that BSE geographic-based blood donor deferral policies have been prudent and remain justifiable. Next slide please.
We put to the Committee no specific options although Peter Gantz who I think will be here this afternoon laid out the three options that Canada is addressing, one of which is through keep current policies and the other two we'll discuss now. There are really only a limited number of ways in which risk can be reduced further.
The policies are based on reducing the risk that a donor has been exposed to the BSE agent either in food or through pharmaceuticals. We've had to take residence in a BSE country as a surrogate for food exposure because dietary histories are considered quite unreliable.
The only other exposure of concern has been bovine insulin. That's already part of the deferral policy. There's no comparable bovine product that was made either in the U.K. or in any other BSE country that we're aware of. So that one approach would be to reduce the time that an acceptable donor might have spent in a BSE country or to add new lower risk BSE countries to the list of countries for which there is deferral.
The second strategy would be to reduce the risk that the donor had been exposed to vCJD agent from a human exposure and in 2002, we recommended deferral for anyone who had been transfused in the United Kingdom after 1980. One might consider deferrals for transfusions received in other countries. The Committee itself suggested that we might consider similar deferrals for people who had surgery in BSE country although that remains a theoretical risk whereas the transfusion transmission is now a demonstrated risk. Next slide please.
To help the Committee in their deliberations, there were a number of very useful talks. Robert Will summarized the situation that I just summarized for you. Steve Anderson compared the risk of classic and vCJD. Peter Page, I think, is here this morning presented the American Red Cross Lookback Study of recipients of labile components here in the United States, one hundred and sixteen recipients living more than five years without a single case of Creutzfeld-Jakob Disease.
Steve Anderson did a Fisher Exact Test and it's a highly significant difference. The pathogenesis of the two diseases in regard to their transmissibility by blood appears to significantly different. Louisa Gregori from Bob Roars' lab in Baltimore presented very interesting results of their studies with one leukoreduction filter and found that although about 40 percent of hamster blood infectivity was removed by the filter about 60 percent of it remained in the plasma.
The good news is that although there has been some fear that filtration might fragment cells and release infectivity into plasma, that didn't seem to happen. The other good news is that there is still no evidence to suggest that there is intrinsic infectivity of either red cells or platelets. The infectivity found there appears to be attributable to contamination with plasma which suggests the possibility of technical solutions to reduce the risk more.
Peter Gantz presented recent Canadian policy actions and discussed possible future actions. I've mentioned those. Dob Scott presented the summary of the current policies and then Alan Williams addressed what it would do in reducing risk and what the cost might be if additional policies or enhancement to the current policies were adopted. Next slide please.
This is a crude reduction of some of the information that Alan presented. First, let me remind you that the deferral policies are risk reduction policies. It's not possible to eliminate all risk by deferral policies for the following reason.
If we attempted to defer any donor who had ever been in a BSE country after the beginning of 1980, we found the following projections. If we attempted to defer anybody who had been to the United Kingdom, 23 percent of current blood donors would be deferred. If we tried to defer anybody who had been to any one of the 23 BSE countries, well 22 BSE countries, we won't even mention Canada, 36 percent of current donors would be deferred. It's simply not within the realm of the feasible.
Now let's look at what enhancing current policies might be predicted to do and these are very rough estimates based on certain assumptions. If we attempted to reduce the acceptable time, the time that a suitable donor might have spent in the U.K. during the time period mentioned from three months to one month, we would expect to reduce the risk by an additional four percent over the current 91 percent total estimated risk reduction achieved by the deferral policy and a cost in donors of about three percent which is a very large increase in the number of deferred donors.
If we deferred for transfusion in France, the amount of risk reduction is not quantifiable. But it would be very small. However the loss of donors would also be very small. Alan estimated about a loss of about 1.4 donors per 10,000 and for history of transfusion in Western Europe including France outside the U.K., also an uncertain very small reduction in risk but at a cost of only a total of three donors lost per total of 10,000. Next slide please.
So we put the three questions to the Committee. Are the measures currently recommended by FDA to reduce the risk of transmitting CJD and vCJD by blood products still justified? Do the recent scientific data on vCJD warrant consideration by FDA of any additional potentially risk reducing measures for blood and blood products? If so, comment on the additional risk reducing measures that FDA should consider at this time? Next slide please.
The Committee voted unanimously, 14 to zero, that the current measures remain justified. However, they voted 13 to 1 that the recent new scientific data do not warrant consideration of any additional potentially risk reducing measures for blood and blood products. The one holdout felt that we really needed more information about the seven European cases whether they might have had blood exposure and clearly, that member felt uncomfortable about not deferring donors transfused in non-U.K. BSE countries. After the vote, that concern seemed to be met with some sympathy by other members of the Committee as well, I must say, by FDA staff. Thank you very much. I don't know if there's time for questions, but if there is, I would be happy to answer any that I can.
ACTING CHAIRMAN ALLEN: Thank you for that very complete summary. I will comment with regard to Question No. 2. I think everybody on the Committee who voted no did so with the understanding that they did not believe there was sufficient data or information available at the present time to warrant consideration of specific measures, but clearly there was an expectation that the FDA would continue to monitor the situation as would be blood collection centers and transfusion medicine specialists and that as new information became available, the FDA would bring it to the Committee for consideration. Other questions or comments?
DR. ASHER: I might say in regard to that. We are committed to reevaluating the situation every six months regardless and bringing the issue to, and of course we watch it all the time, the Committee whenever new information as it did in this meeting warrant formal consideration.
DR. HOLLINGER: Dr. Asher, did you say that they are deferring persons who have had transfusions after 1980 from the U.K.? I'm not sure I understood that. In the U.K. but not here.
DR. ASHER: No, people who have received any transfusion in the United Kingdom after 1980 to the present deferral of such people is currently recommended.
DR. HOLLINGER: In this country.
DR. ASHER: In this country.
DR. HOLLINGER: As policy.
DR. ASHER: As policy recommendation.
ACTING CHAIRMAN ALLEN: Okay. Thank you very much. We'll move on to our second committee update which is a statement on Supplemental Testing for HIV and HCV. Dr. Ruta.
DR. RUTA: Good morning, Dr. Allen, Members of the Committee. Thanks for the opportunity to update you on HIV and HCV Supplemental Testing. I'm Martin Ruta. I work in the Office of Blood and if you go to the next slide.
I wanted to update the Committee on supplemental testing and I hope it's helpful, but I wanted to step back a bit and talk about the testing schemes and this is FDA's current policy considerations on donor screening for example for HCV. So one way in which one can view the testing scheme is for blood establishment and the requirement for testing falls with the blood establishment. It's a test donation with a license owner screening test that detects the antibodies of HCV. Then hopefully, all those donations are negative.
As the committee remembers over the past ten years, we've encouraged the development of NAT to capture window period cases. So if the donation is negative, one can view it as sequentially although in blood establishments, it occurs contemporaneously. And one goes on and runs the NAT test and that captures the window period units. So hopefully both tests are nonreactive and donation is used.
Now if one runs the HCV antibody test and the test is reactive, then one can go straight to perform the HCV supplement test. In fact, that's what occurs in the source plasma setting for applicant donors. So I wanted first to have the Committee understand that there are different practices that occur in the blood-for-transfusion setting with regard to NAT testing versus the source plasma setting. In the source plasma setting at least for the applicant donors, if the donation is reactive on the HCV test, they go straight to the supplemental test. So we can go to the next slide.
The next slide says essentially the same thing, but it's now for HIV. So as the Committee remembers, we put a rule into place that says blood establishments have to test for HIV and HCV, they have to use one or more donation as needed to ensure the blood is safe, but we've currently recommended that donations be tested for antibodies to HIV and we have a draft guidance document that's recommended that donations also be tested for NAT.
And again if one runs through this scheme, if one tests the donation using the test to detect antibodies to HIV and that's negative, then one goes on to the licensed NAT test and that's intended to capture the window period units. All right. That's what pretty much happens in the volunteer blood-for-transfusion setting. In fact, my understanding is that they are both run essentially contemporaneously.
In the source plasma setting again for at least the applicant donors and these are the first time donors or people who have not donated in six months, that the HIV antibody test is run and if it's reactive, they go straight to the supplemental test. Now as I mentioned, we've issued a draft guidance recommending the use of NAT and it's my understanding that the final guidance will be coming out very, very soon and possibly may be posted today on our website. So I would encourage you to start looking for it.
Okay. I hope that's helpful to try and explain that there may be different testing schemes that occur within the blood collection setting. Now I want to move on to supplemental testing and this was an issue that we brought to the Committee last March. We asked for the Committee's advice on supplemental testing.
So the current requirements that are in the Reg are up here and I won't read it to you except to say that what we require is that if a donation test reactive on one of the screening of the test, that the blood establishment must go on to further test the donation with the license supplemental test if such a test has been approved.
So the reason that we put in supplemental testing requirements into the Regs is first to clarify for the donor their status whether they are really infected or not. It also places a role in donor reentry. As part of their report that the GAO wrote in 1998, they were finding that not everyone was doing supplemental testing and in fact, that there was inconsistency in notification messages and not everyone was being notified. So we put in requirements of both, that supplemental tests be performed and that the donors be notified when they are deferred and of their test results. The next slide and the next slide.
All right. So we brought the issue of supplemental testing to the Committee last March for your consideration and we thank you for your thoughtful discussion. Actually we tried to bring it a year ago September, but we were rained out and we had the discussion last March on supplemental testing for HIV and HCV. At that point, the Committee, I think what you advised us to do is review the existing algorithms and to look at additional data.
What we've done since then is to establish a public health service working group to try and look at all the data that was collected and try and make some sense out of it. I think where we were last March was that we saw presentations from several people which showed a correlation between EIA reactive samples that were also NAT positive showing that these were truly infected individuals.
A number of the members of the Committee thought that if both the EIA and the NAT were positive that in fact the license supplemental test would not be needed. But the data that we saw last March or the Committee saw last March primarily involved only one of the license NAT tests and in fact there are three FDA approved NAT tests and they are in order of approval, the National Genetics Institute UltraQual HIV I and HCV Test, the Procleix HIV I/HCV Multiplex test and the Roche COBAS HIV I and HCV test.
So we established a PHS working group. If I can go to the next slide. We tried to address a number of scientific questions and these are limited to the blood bank setting. We started off with what we were hoping would be the simple questions and that is if donation is reactive/positive on a license HCV NAT on a single donation and the same donation is also HCV antibody reactive, can those results be used to confirm infection in lieu of the HCV supplemental test? The answer that we came up with was yes, you could.
We asked a similar question for the HIV testing and the reactive/positive results of a license HIV NAT performed on a single donation that is also HIV antibody reactive. We used to confirm infection in lieu of the HIV supplemental test and again the answer we came up with was yes, it could. So let me explain here for, I said, reactive or positive results. In the case of the multiplex test, we actually mean that it's discriminatory reactive. It's reactive with a specific primary for either HIV I or HCV. Okay. If I can move onto the next slide.
I've told you the answer already but where the Committee came out and where the working group is that if the donation is reactive on the HCV EIA screening test to detect antibodies of HCV and the donation is reactive or positive on an individual sample using a license HCV NAT meaning discriminatory reactive for the multiplex test, then as a scientific matter, the license HCV supplemental test would not be needed to confirm infection. This is a scientific statement and as a regulatory requirement, the supplemental test is still required and I'll get to that at the end.
So moving on to the next slide, we come to this, and I've given you the answer for this already for HIV. For HIV supplemental testing where both the EIA is repeatedly reactive and the NAT is positive, we've said that as a scientific matter, the license HIV supplemental test would not be needed to confirm infection. All right.
So now we deal with the more complicated issues in the next slides and that is what happens when the tests don't agree. I think this is sort of where the Committee was left to consider some of the data that was presented and wasn't quite so sure. Where we ended up that if a donation is reactive on a license HCV EIA donor screening test to detect antibodies for HCV and the donation is nonreactive or negative using an appropriate license HCV NAT, negative or nondiscriminated on an individual sample, then as a regulatory requirement, the license HCV supplemental test would still be needed to provide information about the donor's infection status. So these are the ones that are EIA reactive NAT negative. So the RIBA is still needed.
If we go onto the similar consideration for HIV in the next slide, again if the donation is reactive on the license HIV donor screening test to detect antibodies to HIV and the donation is not reactive or negative on the appropriate license HIV NAT or not discriminated on the individual sample, then as a regulatory requirement the license HIV supplemental test would still be needed to provide information about the infection status of the donor.
Let me correct what I said before. Here's where there was a bit of a debate about the science involving alternative schemes to try and resolve HIV infections. So we recognize that there's still a scientific debate involving the use of alternative tests to resolve HIV status.
And if I could go to the next slide. So what have we done? We actually have received a variance request from a blood establishment and we've issued a variance under 641.20 to allow a blood standard to not perform the HCV supplemental test which is a required test under 610.40(e) our testing requirements when the donation was reactive on a license HCV EIA for antibodies and also was positive on the license HCV NAT on an individual donation. If I can go on to the next slide.
There are possible other courses that we could use to address this issue. One would be we could consider whether to relabel the HIV and HCV NAT test, the supplement test, when the NAT is positive. That would require manufacturers actually to come in and seek such changes and we would entertain those requests. In addition, we may need to relook at the regulations requiring supplemental testing and consider changes to those in the future.
Finally, well, almost finally, other issues. Okay. So now we deal with the more complicated issues that I think the Committee was pondering last March. If you remember there were a number of data sets presented and I think what the Committee was struggling with is that there were discordant results on the same sample. So we had donations that were EIA reactive NAT negative or positive on the Western blot but then had been tested on other EIAs and were discordant on some of the EIAs. The Committee was sort of pondering what does this mean and how do we sort this out.
Where I think a step further into the datasets and at this point, we have a lot of questions, just to give you an idea for the type of things that we are looking is some of the discordants actually had very high signal to the cutoffs and were negative on one EIA and positive on another and we had some questions about those. There's been a limited amount of retesting and there may be some testing issues with those particular samples.
There were additional samples that I was hoping that our laboratories could obtain and test for us that have not been retested yet. We run into a phenomenon of the Federal Government where we came to the end of the fiscal year and basically they told me we didn't have any money. So I'm hoping now with the continuing resolution that our laboratories will be able to do some of these studies that I was hoping that they could do.
I think the, I see my time is signaling. So I'll try and wrap up quickly. There are a number of other questions that we're facing with the datasets that were presented and that is how do you know, a number of the presenters were suggesting that the blots were actually false/positive blots and that some were actually real infections.
One of the first questions that we asked was how do you know which ones are real and which ones are not real. We've asked for additional data to sort out which ones are real and which ones are not real. We're waiting for some of those datasets to arrive.
Some of the other issues that we are struggling with are minor things like there were band patterns that were presented which included molecular weights that are not described in any of the current inserts so I presume were errors in transcription. We're dealing with issues that the datasets again involved only one of the NAT tests and only involved the whole blood sector.
We actually didn't see any data from the source plasma sector and whether we would need these additional datasets. So we're wading deeper into the data now and in an interactive dialogue with the presenters and trying to figure out what data is needed. Finally, I'd like to thank the members of the PHS working group who are up here on the slide. So I'll stop and see if there are any questions from the Committee.
ACTING CHAIRMAN ALLEN: Thank you, Dr. Any comments or questions? Yes, Dr. Lew.
DR. LEW: I just wanted to know what percentage of patients who are donors have actually been EIA Western blot positive but NAT negative.
DR. RUTA: Right. Well, this would come from the datasets that were presented and I think in those cases that datasets that we saw ran around five percent of the donors were Blot positive, EIA Blot reactive positive but NAT negative. Now some of those were said to be real infections and other were asserted to be not real infections. So we're trying to sort through those.
ACTING CHAIRMAN ALLEN: Other comments or questions? This is obviously a very important area and we look forward to further discussion about that in learning how the FDA intends to resolve it. We will actually deviate a little bit from our published agenda at this time and move to an open hearing if you will and allow Dr. Kleinman to make a combined statement on HIV and HCV supplemental testing. This is a combined statement from the AABB, ABC and ARC. Yes, if you would like to come up here, that would be fine.
Now I need to read a statement first because this is an open public hearing. So bear with me. Open Public Hearing Announcement for General Matters Meetings. Both the Food and Drug Administration and the public believe in a transparent process for information gathering and decision-making. To ensure such transparency, at the open public hearing session of the Advisory Committee meeting, FDA believes that it is important to understand the context of an individual's presentation.
For this reason, FDA encourages you the open public hearing speaker at the beginning of your written or oral statement to advise the Committee of any financial relationship that you may have with any company or any group that is likely to be impacted by the topic of this meeting. For example, the financial information may include the company's or group's payment of your travel, lodging or other expenses in connection with your attendance at the meeting.
Likewise, FDA encourages you at the beginning of your statement to advise the Committee if you do not have any such financial relationships. If you chose to not to address this issue of financial relationships at the beginning of your statement, it will not preclude you from speaking. Dr. Kleinman.
DR. KLEINMAN: Good morning. I'm Dr. Steven Kleinman, Chair of the AABB Transfusion Transmitted Disease Committee. With regard to conflict of interest, I do have and have had some consulting arrangements with companies that manufacture NAT assays.
I'm reading this statement today. It's a joint statement endorsed by AABB, American Bloods Centers and American Red Cross. Our statement today is similar to that presented to the Committee in March 2004 when supplemental testing for HIV and HCV was last discussed. The purpose of today's statement is to emphasize the importance of this issue and the urgency to make rapid progress especially with regard to HIV.
AABB, ABC and ARC strongly endorse the revision of supplemental testing algorithms for donors testing EIA, Repeat Reactive for HIV and HCV antibody as previously presented to the Committee during the March 18 meeting. These algorithms were subsequently summarized in a letter from AABB to Dr. Epstein on August 10 of this year.
We acknowledge the FDA for moving forward with the integration of nucleic acid tests into supplemental testing algorithms. The extensive amount of data presented at the March BPAC meeting clearly established the scientific validity of using reactive NAT to determine the existence of HIV I or HCV infection in EIA repeat reactive donors. In such circumstances, HIV I Western Blot and HCV RIBA add no useful information to the evaluation of the donor's status.
So this is good that we heard today that FDA and the PHS Committee are scientifically in support of this. However the inclusion of NAT in the HIV supplemental testing algorithm will not prevent the classification of many donors as HIV Western Blot indeterminant since only three percent of HIV I/II repeat reactive donor samples are positive leaving 97 percent of such specimens to be tested by Western Blot. In cases with non-reactive HIV I NAT and alternate HIV I/II negative alternative HIV I/II EIA results, the data indicate that the Western Blot has no usefulness.
It's not surprising that in alternate HIV I/II EIA is superior to a Western Blot for confirmation of HIV I infection. This is a direct consequence of the continued improvements in the sensitivity of HIV I/II EIAs.
In contrast, no similar improvements have occurred since the first use in the licensure of HIV Western Blot. We now and have for some time been in the paradoxical situation in which the Western Blot originally licensed as the HIV I supplemental assay is less sensitive than is screening EIAs and is certainly the least specific test used in the blood donor setting.
While the scientific validity of using NAT or an alternate EIA in supplementing testing algorithms is a necessary prerequisite for making a change, there is a much more compelling reasons for such a revision. Indeterminant test results create confusion and anxiety for the donor. This is well documented by REV's investigators who surveyed donors about their perception of and reaction to the notification process.
Responses were received from 203 donors with indeterminant results for HIV antibody or P-24 antigen, HCV and HTLV. These data published in "Transfusion" and presented at the March BPAC indicate that the vast majority of such donors were both upset and confused when initially notified of their test results and remained upset and confused six to 12 months later. This is not surprising when donor have been told based on their indeterminant Western Blot results that there is some possibility that they are infected with HIV I.
Unfortunately, such notifications are not confined to only a handful of donors. According to American Red Cross data, approximately half of all HIV EIA repeat reactive donors have an indeterminant Western Blot result. When the ARC data are projected nationally, we estimate that over 5,000 donors receive this message annually in the U.S.
This translates to anxious donors contacting blood centers each day confused and frustrated about their HIV indeterminant result or occasionally and even worse, their false positive HIV Western Blot results. This situation has not changed since 1987 so we've been living with this now for 17 years.
Instructions for carrying out the HIV I/II EIA screening assay state, it is recommended that repeatedly reactive specimens be investigated by an additional more specific or supplemental test. Since the majority of donors with indeterminant Blot results are not infected with HIV I, it is apparent that the Western Blot assay is not achieving the enhanced specificity expected of a supplemental assay.
Until recently, this situation was a necessary but unfortunate outcome of the notification process given that there were no alternate means of assessing the donor's infection status. However, such disservice to the donor community cannot be justified when we have the tools available to do better. Testing technology has advanced to the point where donors would be more accurately apprised of the meaning of their test results if FDA were to permit blood centers to use the AABB proposed testing algorithms.
The Committee has agreed that revised supplemental testing algorithms is the correct course of action that this Committee, the BPAC, based on scientific and ethical considerations. However there still appear to be hurtles to cross. As Dr. Ruta told us, 21 CFR 610.40(e) states that you must further test each donation including autologous donations found to be reactive by a screening test whenever a supplemental, that is an additional more specific test, has been approved for such use by FDA.
Now NAT assays or licensed HIV I/II EIAs do not currently carry these supplemental testing claims. However these assays have undergone rigorous review by FDA for donor screening claims and as such they meet all CGMP requirements including those for clinical and analytical sensitivity, specificity and reproducibility.
Furthermore, over five years of data establish the usefulness of NAT to confirm HIV I and HCV infection status supplemented by HCV RIBA or HIV I/II alternate EIA in circumstances in which many pool (PH) NAT is nonreactive. The use of an alternate HIV I/II EIA coupled with IV NAT, individual donation NAT, as included in the AABB proposed algorithm will serve to reduce substantially the number of HIV I Western Blots that will need to be performed.
Considering these facts, we urge BPAC to recommend to FDA that it find a way to allow both NAT and the HIV I/II alternative EIA approach to be a major approach of HIV and HCV supplemental testing algorithms without requiring new clinical trials to establish this claim. To this end, we also encourage the manufacturers of NAT and the HIV EIAs to work with blood centers to submit the required supplemental claim data to FDA for expedited review.
Lastly, and I think very importantly, use of the proposed supplemental testing algorithms has no impact on blood safety since all EIA repeat reactive units are discarded and the donors are deferred. Furthermore, these algorithms, the use of these other supplemental tests like an alternate EIA, is not being proposed for the purpose of donor reentry.
So to restate this is a tool by which to give donors better notification methods, not a tool that at all affects whether the unit will be transfused or whether the donor will be eligible in the future. Therefore, supplemental testing algorithms should be adopted based on their ability to provide a timely and accurate result to a blood donor who is taking the time to make a generous gift. The AABB proposed algorithm is well suited for the purpose of accurately informing a donor of test results. Thank you.
ACTING CHAIRMAN ALLEN: Thank you, Dr. Kleinman. Any questions or comments for Dr. Kleinman? Thank you. At this point in the meeting, we will go back to our opening since Dr. Epstein is here. We will go ahead and proceed with the Topic 1 which is FDA's current thinking on reentry of donors previously deferred for anti-HBc reactivity. We have a series of four presentations in this segment. The first introduction and background by Dr. Kaplan. I'll be pleased when wireless technology simplifies the transfer of computers.
DR. KAPLAN: Good morning. I'm Geraldo Kaplan. I will introduce for you the reentry for donors that were deferred for repeat reactivity with anti-core tests results. So this is a current thinking session and the FDA would like to present to the Committee a proposed algorithm that will allow reentry of donors deferred for testing repeat reactive for antibodies to hepatitis B surface antigen on more than one occasion.
This guidance dated September 10, 1991 for the screens of anti-HBC it says that donations for transfusion should be tested for HBsAG and anti-HBc. Only reactive units should be transfused. The donors should be indefinitely deferred when they test repeat reactive more than once and that donor reentry algorithms were not recommended at that time because there was no supplemental test, basically a more additional more specific test for anti-HBc.
The consequences of this anti-HBc screening were that although anti-HBc donor screening contributed to blood safety, many donors were indefinitely deferred because of potentially false positives anti-HBc results. In the BPAC meeting in December 1998, FDA and AABB presented to BPAC similar reentry algorithms based on negative test results for hepatitis B surface antigen, anti-HBc and anti-HBsAG.
The Committee did not recommend reentry because the American Red Cross data showed that some HBsAG and anti-core negative samples were HBV reactive using an experimental NAT. As you stressed that in some tests the anti-HBV were also positive so some samples where one was positive with one test and negative with another one.
We have had recent developments basically that hepatitis B in NATs have been developed for screen donations in meaningful format. They can be used to test individual donations. It does enhance its sensitivity. The FDA is considering testing algorithms to permit reentry of donors that will include use of this sensitive HBV NAT and I will talk about that proposed algorithm in a few minutes.
Some of the considerations is that will permit reentry only on the premises that (1) historical test for anti-HBc were false positives and (2) that there is no evidence for past or present hepatitis B virus infection. Also reentry base on testing of hepatitis B surface antigen, anti-core and hepatitis V DNA by the NAT that antibodies to HBsAG is not part of this reentry or algorithm because extensive hepatitis B vaccination programs have been in place for a number of years and many individuals are antibody positive so this is not a good marker of hepatitis B infection at this point.
So what's our current thinking? A donor that has been indefinitely deferred because of having tested repeated reactive for anti-HBc on more than one occasion may be reentered if after a meeting of eight weeks subsequent to the last repeated reactive anti-hepatitis B core test a new sample is collected from the donor and this sample tests negative for surface antigen, anti-HBc and hepatitis B NAT and the sensitivity that we're looking for is 95 percent detection at less than 10 copies per mil. However, we are at this point flexible on that limit and this test should be FDA license assays.
Also that whenever a donor presents at a blood center to the NAT subsequent to the negative test for surface and anti-core and HBV NAT, all donors with that criteria for donors of whole blood and components are fulfilled. So basically that's what I would like to present to you. The data of the full evaluated algorithm is being collected at the present time and basically the part missing is using a more specific test for anti-core. So we will hear a presentation by Dr. Susan Stramer regarding her data on NAT testing of repeat reactive samples. At this point, I would like to introduce Dr. Blaine Hollinger that will give us an introduction on serology.
ACTING CHAIRMAN ALLEN: Can we take just a second first? Are there any questions first of all for Dr. Kaplan's setting of the stage? I've have just one quick question with regard to the sensitivity of the HBV NAT. You talked about a sensitivity of 95 percent detection at 10 or fewer copies per MIL. What is the range there that you actually find in the FDA license assays?
DR. KAPLAN: Well, there is no license assay. The FDA last week presented a set of possible license in the near future of HBV NAT. That is a meaningful assay so the sensitivity of that meaningful assay that it's lower than the ID NAT in donation. Unfortunately, I think that Rush (PH) had given a presentation, the last presentation of the session. I haven't seen him in the room. They are here. Good. So they will probably talk about the sensitivity of their assay that would meet this 10 copies requirement and I understand that other assays could reach that limit though we are flexible at this point on that requirement. So restating what I'm saying is that the future license test are meaningful and this is probably pushing a little bit the envelope because it will be done on ID NATs single units.
ACTING CHAIRMAN ALLEN: All right. Thank you. Dr. Hollinger.
DR. HOLLINGER: Thank you, Dr. Allen. I'm going to try to give again a brief overview of serology to those of you who may not be quite so familiar with the hepatitis B virus. I think any time that you start with serology you need to understand something about the mechanisms briefly of viral multiplication.
With any viral infection usually initially specific cells are targeted for infection and of course where hepatitis B virus this is the hepatacytes. The genetic material then from that virus is introduced in some fashion into the cell. Following this, genes are expressed and viral genomes are replicated and following this replication there are both non structural proteins which are important for the viral replication as well as structural proteins which are important for the assembly and release of virions. In most cases following this but not always cells are destroyed and disease develops.
This shows these particles that are found in hepatitis B virus infections. It's really interesting because initially we were all expecting to find really virions present and in this virus, you found a very large number of these non-infectious particles. Indeed the plasma derived vaccine initially was made from this small particle here. These long tubular forms, the tubulars you can see coming off of the surface of the virion itself is the surface antigen is composed of these small particles here.
There is no infectious nucleic acid in these particles. So you have surface antigen here and on the surface of the virion itself, there is probably 10,000 or more non-infectious particles per each infectious virion that's present. Then of course inside this virion is a nucleocapsid that protects the nucleic acid which is inside of this particle. Next slide please.
The nucleic acid for hepatitis B virus has four open reading frames. Two of them are important for the discussion here today and that is the open reading frame which is important for the surface antigen and of course it has its own antibody, the anti-HBs and then there is the open reading frame that produces the core antigen important for the nucleocapsid. Part of this core antigen also is important for the production of the HBe antigen. The e antigen is not part of the structural protein of the hepatitis B virion but does circulate free in the circulation indicative of an active replication of virus. Next slide please.
This just again shows the life cycle of the hepatavirus. It enters the cell. The coating is taken off. The nucleocapsid gets into the nucleus from which there is transcription of the genome with translation. It is then packaged into the nucleocapsid where there is synthesis, minus strand and plus strand synthesis. It's then budded. It goes through a budding phase in which the envelope is found in the virions which is then exported out the cell. Next slide please.
It is interesting. If you look in this cell, this is a freeze fracture EM if you will of a cell and what's very interesting in these cells is that there are nucleur pores. We wondered how these nucleocapsids could get inside the nucleus as well as being present in the cytoplasm. So this slide shows these nuclear pores and the next slide please.
This shows an infected cell with hepatitis B virus in which the nucleus is loaded with these small nucleocapsid some of which or most of which contain the virion. There are also nucleocapsid here in the cytoplasm. Indeed in the very early phases of infection, nucleocapsid is probably excreted free into the blood stream. In fact even as long ago as 1975, we reported the presence of free nucleocapsid in the blood of patients in the early phases of their infection which was found at that time with DNA polymerase but it preceded the development anti-core or anti-HBc. Next slide please.
Now what about the course of HBV infection in general. Next slide.
Before you understand anything about the course of infection, you have to have some grasp of the sensitivity of the assays which are available today. This slide goes from micrograms down to attograms here. Picograms, fentograms and attograms and so on getting down the HBV genome. The hepatitis B virus has one picogram of the HBV virus which is equivalent to about 280,000 genomes in there. So that's about at that level.
The hepatitis B surface antigen test which are currently available, I mean the unlicensed test. Some of the unlicensed test can get teched down one tenth of a nanogram or less in this range here which is approximately 100 picograms. You also then see that as you get into radioautography, hybridization assays maybe that could detect in this level here, some of the very first assays might detect only 750,000 genomic equivalents and then as the tests were developed and you got into PCR and then into nested PCR and into some of the amplification assays, you began to move down toward this range here where you're almost testing or evaluating one HBV genome circulating per ML of blood.
So all of these tests are important because it tells us something about some of the studies that were done previously when, look at the next slide and you can see this on the next slide. Let me go on with this first. HBV DNA in the blood is detected about two to five weeks after infection and up to 40 days before the hepatitis B surface antigen is detected with a mean of only six to 15 days. It rises slowly. It's distinct from hepatitis C virus infections and it's at a relatively low level perhaps maybe only 10,000 genomes per ML or 100,000 or less during the seronegative period. Next slide.
HBsAG appears one to three week before the ALT becomes abnormal or three to five weeks before the onset of symptoms or jaundice. It reaches the peak during the acute stage of the disease and then it declines to undetectable levels within four to six months in most of the individuals who resolve their infection as is true for probably 97 to 99 percent of immunocompetent individuals, adults. Next slide.
This slide I think points out again the relationship between HBsAG and HBV detection as we get more sensitive. The earlier tests maybe could only have a limit of detection of about 1,000. When you look at HBV DNA and those only about 66 percent of them were positive for HBV DNA.
As the tests became more and more sensitive and we are now down to 20 or 10 or 1.3 IUS per ML of detection, you can see that virtually all or at least most of the HBsAG positive material contains HBV DNA. This also just throws in here at these levels here some of the positivity in samples that are anti-HBc positive only, about 13 percent with this particular report and nine percent here. Next slide.
The third product is IgM anti-HBc. IgM of course is one of those early acute phase products which occurred. It's indicative of on-going viral replication when present. It appears acutely at the onset of an ALT abnormality. It's primarily in the acute phase a 19S component. It's present but undetectable in some chronic infections.
Some people would say most chronic infections at a level that you usually don't detect it because a current IgM assay starts at an evolution of one to 1,000. This was initially set up to avoid a prozone (PH) which occurs at one to 100 levels or higher.
It is a 7S IgM fraction. That's kind of interesting because some of the new reductant assays that are available that use reductants like cysteine e or diathiathriatol (PH) usually break down the 19S component to a 7S component and often are more sensitive because of that when you add specific antibody present. So you don't lose the sensitivity of the assay in most cases. The IgM anti-HBc may reappear during reactivation of HBV. Next slide.
Now the total anti-HBc test and we say total just like we do for the total anti-HAV test is because it can detect both IgM and IgG. It is not just an IgG assay. It is detected in past or present HBV infections. It does not result from the hepatitis B vaccination which uses only HBsAG and therefore the antibody response is only anti-HBs. Next slide.
And finally you have anti-HBs which comes later. It is the neutralizing antibody which occurs during recovery and after vaccination. It may become undetectable in up to 20 percent of patients after several years of follow-up. The next slides shows this.
If you can see here, here's an acute infection here and after many years, what happens is the anti-HBs is not a very strong immunogen as compared to the anti-HBc and so the antibody levels that circulate in the blood stream are much lower. So over time, the anti-HBs may disappear. It's very unusual for the anti-core antibody to disappear. So out here many years later, all you'll have is anti-HBc only.
If you take these individuals and vaccinate them or give them the regular vaccine within two to four weeks they will generate an anamnestic response which is one way you can try to determine whether or not this is anti-HBc only from a remote infection as distinct from something else. Next slide.
This slide then looks at the serology of the disease and again as we pointed out what happens is HBV DNA occurring early followed by the HBsAG and the e antigen present here in the bloodstream. IgM anti-HBc occurring early, switching over, not switching over but really switching very early with some IgG here as well and then both circulating. The IgM disappearing. The IgG continuing.
So what you have from this kind of slide here is you show that if you want to evaluate the relative infectivity of the blood, then HBV DNA and HBeAG is the most important thing to look at. e Antigen positive specimen in most cases is indicative of a very active infection with lots of virus in the bloodstream. There are exceptions to everything we talk about here but in general that's a very good rule.
The second rule is that the presence of IgM anti-HBc helps you differentiate in most cases acute from chronic infection. And a third rule is that the presence of anti-HBs and anti-HBc is indicative of immunity. Next slide.
This then shows the progression to chronic hepatitis B. Of course in very young infants born to mothers who are e Antigen positive perhaps 90 percent of these infants will become chronically infected. But for the immunocompetent adult, it's probably one to three percent that will become chronically infected. We used to think it was 10 percent, but we know now that many of those patients had reactivation of chronic and not really acute hepatitis B which is why that initial level of 10 percent was felt to be the resolution of disease.
So in this case what happens is the patient becomes positive. Their HBs antigen remains elevated for more than six months. That's an arbitrary level to establish chronicity from nonchronicity. As you get more sensitive tests, of course I'm sure those arbitrary levels might have to change a little bit, but basically these patients remain HBsAG positive with a total anti-core.
There is no antibody that's usually developed that you can detect in most cases. They are e antigen initially and as years and years go by, about five to 15 percent a year will go from HBeAG positive to anti-HBe positive. Usually it occurs with reactivation of their disease. Enzymes go up. They may even get jaundice and look like acute hepatitis B.
This limited detection is very important because some patients can circulate virus at very low levels below the detection limit of your assay and therefore they will be negative but there may be anti-core present only and that may indicative of that disease. Next slide please.
Now this sort of summarizes a couple of things which I've said and it goes through the factors that we just talked about. These are HBV DNA column, HBsAG, anti-HBc and anti-HBs. The first new HBC DNA positive is usually in the presero-conversion window period.
Next, if they develop HBsAG but are still negative for anti-core and anti-HBs this is usually in the early acute infection. Anti-core is then developed which is then indicative of an HBV infection either acute or chronic. You can't tell at this stage unless you do IgM anti-core.
As I mentioned, a few patients will have IgM anti-core who have chronic disease. The difference is is that IgM anti-core is at very low level, usually below three times the cutoff level as compared with an active acute infection which is very high. So that's a good way of determining whether this is an acute reactivation of a chronic disease versus acute disease.
Then you have patients who are anti-HBc and anti-HBs positive but have no DNA or surface antigen. This is usually indicative of a previous infection with immunity. Next slide.
The thing we're going to talk about a lot today has to do with this group here which may or may not have HBV DNA in the blood. They are negative for surface antigen but they are positive for anti-core. The total anti-core, I'm talking about here and they are negative for anti-HBs. This could indicate either a low level carrier as we talked about where the antigen cannot be detected.
It could be an early convalescent period in which case the IgM anti-HBc will be positive and these patients will also be anti-HBe or HBeAG positive as well in that window period. It could be HBV infection in the remote pass as I discussed a minute ago or it could be a false positive or nonspecific reaction. A fifth one would be passive transfer of anti-HBc as say from a mother to her infant or through some blood products.
Finally, the other ones. This is a patient for all of these markers here but positive for anti-HBs. This is the kind of response you would expect after receiving the vaccine. Then of course if they are all negative, it usually excludes HBV infection. Next slide.
I want to just dwell just a little bit on the anti-core positive only group, the isolated group or the solitary anti-HBc group. This just looks at the prevalence of isolated anti-HBc of blood donors and HBV DNA in those samples. It's a large group of patients, about eight studies here with a large group of patients and you can see that the anti-HBc only population, that's without anti-HBs, but anti-HBc only, no HBsAG, no anti-HBs, that it goes from a 0.07 percent up to 4.8 percent depending on the region of the world with sort of a median of somewhere around 0.3 percent.
The HBV DNA levels in these studies again you have to remember that there are different degrees of sensitivity when these assays were done, but they ranged here from zero up to 3.9 percent positive in those particular individuals. Next slide.
This slide shows the HBV DNA detection in anti-core positive only blood donor samples. Depending on the prevalence of chronic HBV infection in a population in this group the HBV DNA detection was 3.7 percent. In a population where there was a lot of virus around in that endemically, it was up to 24 percent in this study. Next slide.
Now finally the last thing I want to talk about is just a little bit about HBV transmission from HBsAG negative donors. Next slide.
I'll start just briefly with a study that we did many years ago and again you have to understand that the sensitivities of the assays change and that's why I want to bring up this study because it points out the difficulties with looking back 10, 15, 20 years ago or even looking at assays that were done 10 years or so. In that study, we found HBV infection occurring in about one percent of the recipients of blood transfusions that were anti-core positive, but HBsAG negative and the untransfused control was less than ten percent.
There were five recipients who were co-infected with HCV in this study. I'm not talking about those. There were ten that had 12 implicated donors with HBV alone. Next slide.
Six of these donors, now this was done as I told, these were all HBsAG negative by the initial test that we did, but with a more sensitive test about ten years ago, three of them were actually found to have HBsAG in their bloodstream. It may be possible with even the more sensitive assays today that some of the other assays, some of the other donors, may also have HBsAG if you looked at them with the newer test. But there were six individuals here that were positive for anti-core, negative for HBsAG and HBV DNA. The same thing I said about HBsAG can be said about HBV DNA. Next slide.
In this particular study of the individuals that were anti-core positive only that had no anti-HBs, 17 percent of those donors were associated with a hepatitis B case. Of the individuals that were anti-HBc positive that had anti-HBs in their blood up to 9.9 MIUs per MIL or International Units per liter, ten percent were associated with the case and most importantly, none of the donors that were anti-core positive only that had a high level of anti-HBs were associated with the case.
I must say that going through the literature I have yet to find a case of hepatitis B that has been transmitted from an individual who had anti-HBs and anti-HBc with a level that was at least above 10 or certainly above 100 regardless of their HBV DNA status. Next slide please.
So in looking at the risk of hepatitis B following receipt of anti-core positive products from blood or organ donors, 17 percent in our study here showed this. Allain showed three at ten percent.
Among organ donors, it's much higher. These are now organs that were given, not transfusions, but organs that were given from patients who were anti-core positive and they may have anti-HBs and you can see a very percentage of those showed the development of hepatitis B. Immunosuppressed individuals. Next slide and the last slide.
This also shows anti-HBc transmission from pregnant females to their infants. There were 66 mothers with anti-HBc reactivity only. Three of the infants had high ALT levels. Two had HBsAG and one HBV DNA without HBsAG. The HBV DNA was found in the leukocytes of two carrier mothers and in the cord blood of leukocyte samples, the infants became carriers with elevated ALT levels.
So I hope that this gives you some idea now as we're going to start talking about these issues about anti-core gives you a background of the serology of this disease. Thank you very much.
ACTING CHAIRMAN ALLEN: Thank you. A quick question. You showed data about the 12 donors that were implicated in transmission and then tested with later or more recent assays. I assume the testing was done on old stored samples of serum.
DR. HOLLINGER: It was done on stored samples, stored minus 70.
ACTING CHAIRMAN ALLEN: Thank you. Questions for Dr. Hollinger. Yes, Jay.
DR. EPSTEIN: Blaine, can you comment on the sensitivity of the DNA assays that were used in these retests?
DR. HOLLINGER: On the retests?
DR. EPSTEIN: Yes.
DR. HOLLINGER: They were certainly more than, I would say probably in most cases more than 100 in there, but I don't know specifically. These were done in 1993 I believe. So it wasn't the assays done with PCR. Well, there was PCR but it wasn't done with the more sensitive assays that we have today. I can't tell you exactly, Jay. I don't know.
ACTING CHAIRMAN ALLEN: Any other questions or comments? Yes.
DR. GOLDSMITH: Has the sensitivity of the anti-core changed over time, the tests that are being used?
DR. HOLLINGER: The tests that are currently being used, the licensed tests, probably have not had a great deal of change in sensitivity. I mean if you go back 30 years or 20 years, yes, but the more recent ones not very much.
ACTING CHAIRMAN ALLEN: Did it change as the antigen in the test, wasn't it initially derived from an infected chimp or nonhuman primate lever and then became the recombinant test? I assume that the sensitivity probably changed with that. Okay. Other questions or comments? Yes.
DR. HARVATH: I was wondering in the last slide you showed where the transmission from mother to newborn, do you know whether in those studies those were from Asian countries or do you know the ethnicity of that? And would we have a different concern in a population, let's say, an Asian country where there would be higher incidence overall of HBV infection?
DR. HOLLINGER: Liana, I can't remember if those were from Asian populations or not. I have to go back and look it up again. Sorry.
ACTING CHAIRMAN ALLEN: All right. Any other questions? Our next speaker is Dr. Susan Stramer from the American Red Cross, studies of deferred donors.
DR. STRAMER: Thank you very much. For those of you who have a handout, I've updated my slides so please bear with me. But the Committee should have the new and improved version. Hopefully, it's improved. It's certainly new. Can we go to the next slide?
This is what I hope to cover today. The current situation with anti-core testing, to show you reactive rates and the efficacy of the 2X deferral policy that Dr. Kaplan outlined, the history of the reentry algorithm development, what happened at prior BPACs which was already highlighted and then what successes we've had as a AABB task force is looked at the issue of anti-core reentry.
I'll review data of a pre-IND pilot study that we did with NGI, the current status of an IND that we have for testing anti-core repeat reactive donors for DNA which is also with NGI. Preliminary data was presented by Dr. Richard Smith at the June BPAC and then I will conclude. Next slide please.
This is during my life with the Red Cross the reactive rates of anti-core. So that's what the beginning of the X axis represents. But what you see of the initial reactive rates and the repeat reactive rates are both a linear decrease over time. So we are calling out anti-core repeat reactive donors as we lose true positives and false positives. This was 9/11 but also you see that the pattern of IR and RR rates parallel one another indicating that it's probably related to a characteristic of the test. Our mean repeat reactive rate is 0.44 percent and it's over the last fiscal year. Next please.
We know that no confirmatory test exists for anti-core. Neither does a standardized confirmatory strategy and also there's high non-specificity of tests currently in use. The historical and present repeat reactive rates I showed you ours at 0.44 percent have ranged from about 0.4 to 1.6 percent.
The estimated majority of these are false positives and from some email exchanges that we've had over the last couple of days with some blood centers, I've put together the low and high reported for blood centers of false positivity based on in-house algorithms such as anti-HBs, repeat anti-core with a second ELISA, etc. So we have this range of false positivity. It's obviously dependent on the specificity of the test used.
The policy for anti-core repeat reactivity is that if you're core reactive for the first time you may donate again. But there may be a negative impact of a repeat reactive notification on a donor returning to donate. They may not understand what we're trying to tell them. But if you're anti-core repeat reactive twice, you're deferred.
Now in trying to determine how many deferred donors we have who lack other deferrals, that is their anti-core repeat reactive only and otherwise would be suitable for donation, the Red Cross has put together data since we have been tracking this at greater than 200,000 donors over this time period. However, the number is probably considerably higher because we and most blood centers implemented core screening in 1987 and then this doesn't include 2004. So perhaps the number nationwide if we represent about half may be close to one million donors. Next please.
What is the success of having a 2X anti-core deferral option? That may tell us a little bit about what the likelihood of donors who will come back if we did have a reentry algorithm. These data will be presented by Chang Fang and co-workers at this year's AABB meeting, but I will highlight the findings.
I'm going to present data for 3.9 million donors representing 6.5 million donations from the year 2000. They were the anti-core repeat reactive donation and continued donation history was examined from 2000, that's the index year, plus three additional years to look at their return history. We excluded autologous and donors with other deferrals.
The ortho anti-core LIs (PH) was used for the entire period of time and for this period of time, I showed you why repeat reactive rates have been decreasing, but for this period of time, our repeat reactive rate was 0.64 percent and for control population those were anti-core nonreactive. We selected first time and repeat donors at 500 selected at random per month for the one year period of time. So we had about 6,000 for each group. Next please.
The total number of first time donors, 36 percent of the 3.9 million was 1.4 million. 1.4 percent of the first time donors tested core repeat reactive. Looking now over the next three years, 81.5 percent never came back.
In comparison to first time donors where our control was 54 percent came back. Of those who did return, that is the remainder which is about 20 percent, 88 percent were core repeat reactive at their donation. Of the remaining 12 percent who remained eligible which is 428 total donors, 14 percent became anti-core repeat reactive in the next three years. From this 14 percent, 98 had subsequent anti-core nonreactive donations from 60 donors ranging from one to seven donations per donor. The remaining 86 percent had 809 subsequent anti-core nonreactive donations and this was from 368 donors with a range of one to 13 donations per donors.
So the overall yield for first time donors who were core reactive for the first time was 0.016 donation per donor per year. I don't know if that equals to your pinky or your big toe but it's certainly not a lot of success. Relative to controls, we have 0.74 donations per donor per year from the control group. Next please.
Now looking at repeat donors, 2.5 million or 64 percent of the total, 0.24 percent were repeat donors who tested anti-core repeat reactive. Similarly to the first time donors, 80 percent did not return in three years versus 26 percent of the controls. Of those who did return, 38 percent were anti-core repeat reactive for the second time on the subsequent donation.
Of the remaining 62 percent who remained eligible, that's 752 donors, 12.5 percent were anti-core repeat reactive in the next three years. From 12.5 percent, we had 224 subsequent anti-core repeat reactive donations from 94 donors with this range, one to 23 donations per donor and for the remaining 87 percent who were not deferred in the next three years, we had 3,000 subsequent anti-core nonreactive donations from 658 donors with a range of one to 57 donations per donor. The overall yield was 0.18 donation per donor per year which relative to the controls is lower. Controls was 1.36 donations per donor per year. Next please.
You can skip this slide and skip the next slide. These were provided to the Committee to let you see how the data were derived. Next please.
So of the total 3.9 million donors in 2000, the donor return rate is low. Three hundred sixty-eight of 1952 anti-core repeat reactive donors who were first time donors, their return rate was 1.9 percent. Six hundred and fifty-eight of 549 (SIC) repeat donors successfully donated for donation over the next three years or 11 percent.
Of those who did return, high rates of 2X anti-core reactivity that was 88 percent of first time, 38 percent in repeat. The total successful donation yield per year is low and these were the numbers that I quoted, 0.16 for first time, 0.18 for repeat and 0.74 for first time controls versus 1.36 for the repeat controls or 46 and 8 times higher for the control group. That is their yield of successful donations. Next please.
So the 2X deferral policy is of limited yield. The impact is greater on repeat donors who we lose 80 percent for core reactivity on the first time donation versus 26 percent who will come back. The anti-core reentry algorithms are projected to have higher yields if a different test is introduced. That is the blood system converts to a different method. We have two hurdles here. One is that the donors don't return and secondly, the donors continue to be repeat reactive when the same tests are used. Next please.
So where do we stand? At the December `98 BPAC, this was reviewed by Dr. Kaplan, but it was our data that caused some concern. We were involved in the PRISM clinical data and as Blaine discussed, there were some discordant samples or at least Blaine discussed this category of samples where you may have DNA positivity and isolated core reactivity. Here we had core discrepant reactivity. Our test record was negative, but the PRISM test and anti-core test was positive.
Upon further testing, two our of three of these samples did have weak anti-HBs so they likely were from infected donors. Converse, we had one DNA positive sample that was PRISM negative and ortho positive and that sample was negative for all HBV serologic markers. So we know we had some discrepancies and one explanation for discrepancy other than true HBV infection is false positivity of the DNA test perhaps due to carryover or sample contamination.
So we faced a reentry algorithm proposed such that we would have a follow-up or a clean sample and that sample would have to test negative for HBsAG, anti-core using a second licensed test. We included anti-HBs and an investigational or research HBV DNA assay. Subsequently at the BPAC discussion, the use of anti-HBs was discouraged. Next please.
So we formed the AABB TTD Task Force. We collected preliminary data that I will review from the Red Cross and sent it to FDA DETTD to request that the data that we collected were adequate to qualify a reentry algorithm. The FDA questioned the sensitivity of the DNA protocol and the study has yet to be completed because of the availability of PRISM reagents.
On May, 2003, we again met with FDA to propose a reentry algorithm which is comparable to the one today and I'll highlight the difference. Based on an eight week follow-up sample that test anti-core nonreactive preferably using a different test with comparable sensitivity but improved specificity and -- Next please.
The sample must test DNA negative and an assay that has a sensitivity of less than or equal to 10 copies per MIL. At that time we requested that IND tests could be used and that the next donation then could be used for transfusion if it tested nonreactive by all FDA required tests and the donor was otherwise suitable. We know now that the FDA requires the licensed DNA test for reentry and the qualification of that DNA test must use a licensed anti-core assay. Next please.
So the prepilot study that we did involved 3,000 anti-core repeat reactive unlike donations that were selected in 2001. The surplus NAT samples were contained in our NAT tube to limit contamination. The criterion for inclusion was nonreactive by all other test methods so we would have an anti-core only reactive.
There was no preselection of first time or two time anti-core repeat reactive donors. So we chose 3,000 to allow it to be robust enough so that we would include both one time and more importantly, two time repeat reactive donors. At the time of the study, our 2X anti-core repeat reactive rate was about 24 percent of Red Cross donors. So we could project how many were 2X anti-core reactive of the 3,000 to be 708. Next please.
The samples were tested individually with the NIG UltraQual 8-rxn test that has a 0.2 ml input. The definition of positive, that is the test is run in eight replicates. If any test is positive, the interpretation of the sample is positive. The sensitivity was 9 IU/ml and using NGI's conversion factor of an IU to a copy, it comes out to 31 copies per mil. Next.
So of the 3,000 tested, we had 0.63 percent samples reactive or 19. Eleven had less than 100 copies per mil low level as we know anti-core onlys have and of the eight reactions run, there was an average of only 1.7 reactions that were positive. We have another eight of the 19 with viral loads above 100 but not exceeding 500 with a mean of 287.5 copies per mil and here there was an average of 4.75 reactions of the eight that were reactive.
Data was provided to the FDA as I mentioned. FDA requested additional testing on the residual sample which has not yet been completed and the FDA stated that 31 copies per mil is an adequate sensitivity for anti-core donor reentry which is how we get to the 10 copies per mil or that is they want it sensitivity better than 31 knowing that commercial tests were available to achieve this. So "since higher sensitivity DNA tests are available, it would be preferable to use such an assay instead." Next please.
So as I mentioned, the goal is to complete the study by looking at a second core test so that we could project the number of core nonreactives that would be eligible for reentry using this algorithm. The anti-core reactives would be investigated for anti-HBs and the assumption is that our 19 DNA positives would be PRISM anti-core reactive and we're in the process of getting this going. Next please.
If you put the study that I just described in context with other studies that have looked at similar types of data, we have 0.63 percent rate of anti-core positivity. The Roche clinical trials that were presented at the last BPAC had a 0.35 percent rate of anti-core only that were DNA positive and a study done by REDS had a little bit lower, a 0.24 percent. So this study still yields at the highest number of DNA positivity or one in 37,000. Next please.
So where are we now? We are under IND with NGI. The purpose of the IND is so that we can use the DNA test as a counseling tool for anti-core repeat reactive donors. I mentioned there was no standardized confirmatory algorithm, so this would be one purpose of the study.
We would continue our survey of anti-core repeat reactive donations for HBV DNA reactivity, and, lastly, to limit viral loads and plasma pools for further manufacture, since anti-core reactives are included in frac plasma.
We rolled out the program earlier this year.
We used the eight-reaction test that I described for primer pairs used, each tested in duplicate, and, again, a reactive in an EVAY test is positive. Here we test in pools of 16. Positive pools resolve to the individual positive donation, and all positive samples are quantified.
Samples without adequate volume for pooling or resolution are tested individually. So we have a mixture of pool tests and individual tests.
The sensitivity of the pool test is the eight-reaction test with a 2 mL input ‑‑ this .9 IU per mL, or 3.1 copies per mL. However, when we have requalified with NGI, we have now found a three-fold increase in sensitivity. So it's probably closer to one copy per mL sensitivity.
But in a pool, using the original validation data, it's about 50 copies per mL. When we do resolution testing, the resolution tests is about five copies per mL. And if we test a single unit, it's back to the 31 copies per mL that I mentioned for the qualification ‑‑ the pre-pilot qualification study. The quant assay has 100-copy per mL sensitivity.
All donors in this IND are notified of their test results, and they're deferred if they're even one-time or two-time core reactive and DNA positive. They're deferred if they're DNA negative but two times anti-core repeat active. And deferred donors are eligible for a followup study that we've just initiated, and donors will come back and be tested for all markers of DNA, but we won't do ‑‑ I shouldn't say "all." We won't do E and anti-E, at least at this point.
So how many donations have we tested to date? We've tested 6,006. This is now twice as large as the 3,000 pilot study I mentioned. .44 percent anti-core is our reactive rate, but not all donations were available for PCR testing.
These are the outcome. About 60 percent were negative in pools. About another third of the donations were negative from positive pools. And of those that we were able to get one-time or two-time core data for, about 23 percent were two times anti-core repeat reactive donors.
Now, positives, we have 304, or 5 percent from positive pools, with another six samples that were positive and samples that were never pooled but tested individually. So we have a total of 310 positives of the 6,006, and this translates to about a 2.4 percent pool reactive rate.
If we separate out the 6,006 into HBsAg positive versus HBsAg negative, first, I'll go through the HBsAg positive. 179 of the 310, or just over half, were HBsAg positive. 99.2 percent was their mean HBsAg percent neutralization result, and they were all very high.
Viral loads ranged from below the limit of detection to five billion copies per mL. The median was 5,500 copies per mL. Eleven, or 6 percent, of the 179 had less than 100 copies per mL, but were qualitatively positive.
Now, if we look at the data a little bit differently, if we just look at HBsAg positive samples from our database, about 97 percent, 96.7 percent, are anti-core repeat reactive. And of those, 96.4 percent of these HBsAg positive anti-core reactives were HBV DNA positive. So the data seem to all fit together as expected.
Now, with the HBsAg negatives ‑‑ and these would be the ones who potentially would qualify for reentry, we had 131 of 310. The viral loads were lower than the HBsAg positives, as you would expect, less than 100 to 6,400 copies per mL, and the median was lower than the limit of detection by the quantitative assay. 57 percent ‑‑ again, very similar to the pre-pilot data ‑‑ had less than 100 copies per mL but were qual positive.
So this graph shows you the distribution of the HBsAg positives by viral load, the HBsAg negatives by viral load ‑‑ again, these are all anti-core repeat reactive. The same data, just showing you the lower distribution of virus in the anti-core in the HBsAg non-reactive samples.
So, in total, 131 of 6,006 samples, or 2.18 percent, were anti-core repeat reactive only samples that were DNA positive. This is three and a half times higher than the pilot study which I showed you at .63 percent, and these two numbers are significantly different.
Why would we come up with a higher number now when the sensitivity, actually, by the original qualification data was actually less than the pilot study? I've listed some thoughts.
There has been no change, at least to the assay sensitivity. We have not changed the assay. However, upon revalidation of the assay, it did produce a three-fold increase in sensitivity the way the assay is run today at NGI. There were no changes to donor selection criteria. I mean, perhaps there's contamination in some of these samples. But from the way the data fit together with HBsAg, I don't think that's a high number. But our followup study will resolve the discrepancy.
And my last slide, please.
So, in conclusion, poor assay specificity and the lack of confirmatory test has led to the use of a two times anti-core repeat reactive algorithm prior to deferral. But we know that donor return rate is low. Of those who return, two X anti-core reactivity is high, and the total successful donation yield then per year is low.
Anti-core reentry algorithms are projected to have higher yields if we switch to a new test with improved specificity. That should allow the validation or use of reentry algorithms with anti-core tests of improved specificity. A mass of anti-core repeat reactive donors demonstrates that .63 percent to 2.2 percent have HBV DNA, although the level of viremia is low.
So anti-core testing does have value, but mechanisms should exist to capture those donors that are lost.
ACTING CHAIRMAN ALLEN: Thank you very much, Dr. Stramer.
Quick question with regard to how these donors are handled the first time that they're found to be repeat reactive. What are they actually told?
DR. STRAMER: They're provided with a donor letter and a fact sheet that thanks them for their donation. We found repeat reactive on a test for anti-core ‑‑ you know, we explained the ‑‑ if you tested abnormal on a test for hepatitis B virus, this does not mean that you're infected. And because of the high false positive rates of tests, you're encouraged to come in again and donate.
And then, we give them a little bit of a fact sheet that gives them risk factors and what you should do if you think you're infected with hepatitis B.
ACTING CHAIRMAN ALLEN: So they're told they can come back in eight weeks or ‑‑
DR. STRAMER: Correct.
ACTING CHAIRMAN ALLEN: ‑‑ or ‑‑ and when they come back in, it's not just for testing. They're coming back in to go through the donation process again.
DR. STRAMER: Correct. As any other routine whole blood donor.
ACTING CHAIRMAN ALLEN: So their testing process would be exactly the same in the mini pool as if they had never had an abnormal test.
DR. STRAMER: Correct. If their anti-core repeat reactive again, their donation will go to NGI. Correct.
ACTING CHAIRMAN ALLEN: Thank you.
Other questions for Dr. Stramer? This is certainly a very important database. Yes?
DR. GOLDSMITH: I just wanted to ask two things. On the ‑‑ I thought I heard you say that the plasma from the units that were core reactive was used for further manufacture. Did you say that?
DR. STRAMER: Yes. Anti-core repeat reactive donations can be used for fractionated products, yes.
DR. GOLDSMITH: So the donor units that you collect are split. The cellular components are discarded.
DR. STRAMER: Correct.
DR. GOLDSMITH: And the plasma is used for further manufacture.
DR. STRAMER: Correct. And that's to maintain anti-HBS levels and factor ‑‑ you know, fractionated products.
DR. GOLDSMITH: And I just have kind of a philosophical question about the practice of medicine. When these donors present and have a reactive test, if I understand what you said correctly, they get a letter indicating that they should come back to the donor center to donate again. Are they referred to physicians for medical follow up or ‑‑
DR. STRAMER: Well, we ‑‑
DR. GOLDSMITH: ‑‑ care or individual testing, to try and sort out what their status is?
DR. STRAMER: Well, we ‑‑ firstly, the letter is pretty generic. And it says, "You've tested with ‑‑ you have an inconsistent test result. If you'd like more information, please call the Blood Center." But we explain what test they were used and ‑‑ what test they were found reactive. And because of the high rate of false positivity in this particular test, you're eligible to donate again.
But if you have risk factors, you know, we encourage you not to donate ‑‑ and those are listed on the attached fact sheet. So we go through, you know, typical information about hepatitis B, who is at risk, what to do if you're at risk, if you believe at risk or you're unclear about the meaning of these test results, please see your physician.
So they are referred to the medical system, but they are ‑‑ they are told that they can come back and donate. And if found non-reactive, their donation will be used.
ACTING CHAIRMAN ALLEN: Dr. Hollinger.
DR. HOLLINGER: Susan, a couple of questions, and you may not know the answer to these.
DR. STRAMER: More questions than you've sent me on e-mail?
DR. HOLLINGER: Huh?
DR. STRAMER: More questions than you've sent me on e-mail?
DR. HOLLINGER: Yes. Sorry about that.
DR. STRAMER: That's okay.
DR. HOLLINGER: Just one question about ‑‑ you mentioned that there were 97 percent of the HBsAg positives or anti-HBC repeat reactive. So there's 3 percent that were not anti-HBC reactive, repeat reactive. Were HBV DNAs done on those three? I mean, on that 3 percent? And how positive were those HBS antigens on those 3 percent in terms of ratios?
DR. STRAMER: You'll have to come to my AABB presentation where I discuss those data. The 3 percent are not part of the IND. The IND specifies only anti-core repeat reactive donors who tested.
The HBsAg's confirmed positives ‑‑ now we have switched back from the Ortho test to the Abbott test ‑‑ they split into two groups. Clearly, there are false positive neutralizations that have low signal to cutoff ratios, and lower percent neutralization values. Although about 60 percent still have greater than 80 percent neut vales, they're a large proportion of this half that we believe are false positive have low percent neuts.
So it's really mix ‑‑ a mixture of both positive and negatives. If we were to do DNA testing on this, this would obviously resolve this, or if we were to do donor followup. But we have not pursued that for these 3 percent.
DR. HOLLINGER: The other thing ‑‑ again, you may not have the data. But, again, of those that are anti-HBC positive but, say, PRISM negative, what's the HBV DNA in those? That were ‑‑ the previous tests that are repeat reactive anti-HBC positive that turned out to be negative by another test ‑‑ let's say PRISM test ‑‑ what ‑‑ were those looked at for HBV DNA?
DR. STRAMER: The only one ‑‑ well, the only time we had that discrepant population was in the PRISM clinical trial. And I said we had one of those that was Ortho test of record reactive and PRISM non-reactive. But it turns out that that donor was not HBV infected. We did get donor follow up for that particular donor.
DR. KUEHNERT: First, just a clarification on the sensitivity. So with the pooled method you get a sensitivity that's significantly higher than with the single unit detection method. Is that right?
DR. STRAMER: Significantly lower.
DR. KUEHNERT: I mean, it's ‑‑
DR. STRAMER: It's less sensitivity.
DR. KUEHNERT: Yes. So the ‑‑ so, for instance, for single unit you said it was 31 copies per mL sensitivity versus pools of 16, 3.1 copies per mL?
DR. STRAMER: No. No. That's ‑‑ 3.1 is the test sensitivity. But then, when applied to a pool of 16, I said the pool sensitivity in copies per mL was about 49.5 copies.
DR. KUEHNERT: Oh, okay. Okay. Thanks for that. And then ‑‑
DR. STRAMER: But that 49.5 ‑‑ you know, it depends if you look at ‑‑ NGI filed an IND. And in that IND, they have the .9 or 9 IU per mL, which I reported. But then, before we did the study and the way that we all operate, I wanted to revalidate their test and look at even a more sensitive test. So instead of doing an eight-reaction test, I wanted to use a formula input and use a 16-reaction test.
So we, then, had to requalify tests of record. And at that time we got a three-fold increase in sensitivity of the NGI method. So it may be 50 divided by 3 is the operating sensitivity of the assay.
DR. KUEHNERT: Susan, it confused me, because then it became more sensitive than the single units. That was ‑‑ okay. That clarifies that.
DR. STRAMER: Yes.
DR. KUEHNERT: The second question I had was about the 75 samples that were less than 100 copies per mL but qualitatively positive. And maybe I missed this, but what ‑‑ are you able to quantitate what those are in any way?
DR. STRAMER: Well, linearity of the NGI quant assay, or their standards only go down to 100 copies per mL. So the qual assay, which runs at much more sensitive, you can have a qual positive sample that you can't quantify, because the viral load is too low.
Now, I haven't pushed NGI with more standards, but certainly, as one of their largest customers, that could be done. And it's an issue, because many times, not only for HBV but HIV/HCV/West Nile, we can't get quants less than 100.
DR. KUEHNERT: That would be useful.
DR. STRAMER: Yes. I agree.
DR. KUEHNERT: Thanks.
DR. EPSTEIN: I have two questions, Sue. You noted that among first-time donors with a one-time reactivity anti-HBC their rate of a second reactive anti-HBC was 88 percent, whereas for repeat donors, or previously repeat donors, in a comparable situation there was only 38 percent. That tends to suggest that the true positive rate is higher for the first-time donors. Was that borne out with the DNA data? Did you stratify that? I may have missed it.
DR. STRAMER: No. I haven't done that yet, but it's certainly interesting.
DR. EPSTEIN: So it's an interesting question.
DR. STRAMER: That's right.
DR. EPSTEIN: Okay.
DR. STRAMER: That's right.
DR. EPSTEIN: And then, the second question that I have ‑‑ I've noted that in your histogram, where you showed the viral loads for ‑‑
DR. STRAMER: Yes.
DR. EPSTEIN: ‑‑ the HBsAg negative population and the HBsAg positive population, the histogram is bimodal for ‑‑
DR. STRAMER: Yes.
DR. EPSTEIN: ‑‑ viral load and antigen positives. And can you comment on whether there's an explanation for that?
DR. STRAMER: No. I haven't delved into ‑‑ into that yet, but I noticed the same thing. And there has to be some explanation for that. I just haven't had time to ‑‑ to determine --
DR. EPSTEIN: I was wondering whether that distinguished maybe acute versus chronic infections, but ‑‑
DR. STRAMER: Right. Right, right. I ‑‑ yes. But ‑‑
DR. EPSTEIN: Okay. Thank you.
DR. STRAMER: ‑‑ early acute when they're anti-core reactive versus lower level carriers. Yes, we haven't ‑‑ well, we haven't gotten there yet.
DR. EPSTEIN: I was just curious.
DR. STRAMER: Yes.
DR. EPSTEIN: Okay. Thank you.
ACTING CHAIRMAN ALLEN: Dr. Strong.
DR. STRONG: Just a comment. Most of this data has been presented with the Ortho anti-core assay, although, as Sue has said, they have now shifted back to Abbott for other reasons. But in the clinical trial with Roche, the repeat reactive rate with the Abbott assay was about double Ortho's. So I think their false positive rate is quite a bit higher, and there is still a lot of centers using the Abbott anti-core. Everybody is waiting for PRISM to be approved.
The question I have, Sue, do you have any cases in which you have a surface antigen positive that is negative for core and DNA?
DR. STRAMER: Because we haven't tested the HBsAg only for DNA, I can't answer that question. We know the HBsAg confirmed positives do distribute into two clearly definable groups ‑‑ those that have high ST ‑‑ just like HIV, those with high STCOs that confirm strongly in confirmatory tests, and those that are weakly reactive on EIA screen and don't neutralize to the same extent as this high EIA population does.
So what we would ‑‑ what would be interesting is to know how DNA segregates in those populations.
ACTING CHAIRMAN ALLEN: Okay. From the floor microphone, would you please introduce yourself for the Recorder?
DR. TABOR: I'm Ed Tabor from FDA. I think it's important ‑‑ by the way, Sue, I'm always impressed by the scope of your research.
I think it's important at this point to say that the anti-core test was originally developed in the Bureau of Biologics, the forerunner of CBER, by Drs. Lewellis, Barker, and Dr. Robert Garrity, as a result of basic untargeted research. And it came out of this serendipitous observations resulting from an attempt to see what would happen if you gave cytoxan to a chronically infected chimpanzee.
Now, I state this because in the previous discussion one of the panel members said something about the reagents coming from chimpanzees in the older tests. There's no question that the original research tests used chimpanzee reagents, but I'm ‑‑ I couldn't be wrong, but I don't recall that any of the licensed assays use chimpanzee reagents.
And I think there have been changes in this test configuration over the years, but basically most of the tests have been competitive inhibition assays, and that's been one of the problems with this test and particularly with regard to its specificity.
DR. STRAMER: May I add something to Dr. Tabor's comment? The two tests used ‑‑ one is a competitive inhibition test, and the other is a direct anti-globulin test. And the anti-globulin test is the test with the improved specificity.
ACTING CHAIRMAN ALLEN: Thank you for that historical perspective. I think too often we don't spend enough time looking back at the history of some of these issues, and that was important.
Yes, Dr. Kleinman.
DR. KLEINMAN: Steve Kleinman. I just wanted to comment on one of the issues raised by the panel member about what are the deferral policies currently for anti-core positive donors. And we heard the ARC deferral policy, which is to follow the FDA guidelines and defer after two times and notify the donor after one time. But there's great variability in what other blood centers do.
Many blood centers will defer the donor, or have up until now, deferred the donor after a first time anti-core, basically because they haven't thought that it was worthwhile to allow people to come back a second time.
Secondly, some blood centers have actually on their own decided to, in addition to doing the anti-core assay test of record, they would do a second manufacturers' anti-core assay and/or an anti-HBS assay, and the notify donors based on several different results and stratify their notification message to say there's a greater probability that you may have been infected, that this is a real result, or there's a greater possibility that you're a false positive.
So we don't have uniformity of practice in terms of how we implement donor deferral for anti-core or how we actually go about notifying persons.
DR. HOLLINGER: I like what Sue does when she ‑‑ on some of her slides will show a quotation around anti-core only, just to make it clear that many of these have not been tested for anti-HBS, anti-HBE, or other hepatitis B markers. And I think that's a good way of doing it, so that we're not thinking that anti-core only means just nothing else there.
DR. BUSCH: Hi, Sue. Just a question. The increasing rate of DNA in ‑‑
ACTING CHAIRMAN ALLEN: Would you introduce yourself, please?
DR. BUSCH: Sorry. Mike Busch from Blood Systems. In your recent data compared to the earlier, could that relate to the anti-core test that was employed? Was your earlier work with the Abbott in the more recent drive for ‑‑
DR. STRAMER: No. The entire data set, as I showed, since 1995 we have been using the anti-core Ortho test, actually since earlier than that. So the second or third slide I showed with the anti-core rate shows over nine years of anti-core Ortho repeat reactivity. And the entire data set also includes Abbott HBsAg. It was post our conversion from Ortho 3.
ACTING CHAIRMAN ALLEN: Dr. Strong.
DR. STRONG: I might just add to the complexity of what Dr. Kleinman just mentioned that there is also some centers that are doing DNA. So it really goes all over the map.
DR. STRAMER: Right. That's why I mention there's no standardized confirmatory algorithm. And you seconded it and thirded it.
ACTING CHAIRMAN ALLEN: Dr. Schreiber.
DR. SCHREIBER: Sue, have you made any estimate of what the capture would be of reentry of donors, deferred donors? I did just a back-of-the envelope and it doesn't seem to me that it would be very big based on the million donors that seem to be deferred over a 17-year period. It seems to me that you'd only get somewhere around 100,000 units a year maximum from ‑‑ if you reinstate donors, or less.
DR. STRAMER: Well, I think you have to look at reentry, generically, really has two purposes ‑‑ one, to allow donors who truly believe that they want to give to have that ability to give; and, secondly, but of more frequently less consequence, is an increase to the blood supply, because we're reentering donors.
The yield of reentry for any marker is not high, and certainly is ‑‑ if we went back to 1986, to those donors we initially deferred because of corzine, you know, one, would we even be able to contact them? And after 18 years, you know, they'd look at us cross-eyed. You've finally done something about our anti-core false positivity? That's not a very good message from the blood centers.
So it really is proportionate to the amount of time, or inversely proportionate to the amount of time that the donor has been deferred. So we likely would start, as we have with other reentry protocols with the most recent deferrals and work our way backwards.
But you're right, George. Any ‑‑ you know, one of these reentry have huge yields, but just the ability to do it for those donors. And if any marker we do reentry for, certainly anti-core has the greatest catchment.
Okay. Thank you.
DR. STRONG: I'd like to say "only 100,000 donors." For a blood center, that's a lot of donors.
DR. SCHREIBER: But then you have to divide by three, because her rate was for three years.
DR. STRONG: But you'll also notice that in her data set she has some donors that donated 57 times. Those are the ones ‑‑ those dedicated donors are the ones we'd like to have back.
DR. STRAMER: Well, it's an emotional issue more than anything. I mean, probably more than anything else.
ACTING CHAIRMAN ALLEN: Thank you.
We'll move on to our next presentation in this section, which is studies of deferred donors. Thomas Clement from Roche Diagnostics.
DR. HERMAN: Okay. I'm Steve Herman. I'm not Tom Clement. And I'm going to speak about a small study we did to look at the potential application of the COBAS AmpliScreen HBV assay, which is currently under review, and the reentry algorithm for donors deferred for anti-core reactivity. And this study was conducted by Guy Tegmeier at the Community Blood Center of Greater Kansas City, with Yungfin Yang and Jim Glarda from Roche.
So Dr. Kaplan reviewed the history, so I'll just go through it very quickly. The anti-core antibody test was introduced in the United States in 1987, and, in 1991, the test was licensed for blood screening. And over the past 16 years it's estimated that the components from up to one and a half to two million donations have been discarded due to anti-core reactivity. And testing ‑‑ testing with the second license test has shown that a large fraction of them are likely to be false positive.
So what are the ‑‑ there's a reservoir of donors that exist that could be reentered if there was an algorithm. And with the licensed assay of greater specificity, and the availability of sensitive nucleic acid amplification tests, the tools for reentry algorithm may now be available, or may soon be available I should say.
So here's the current algorithm for how donor and product management decisions are made with regards to anti-core reactivity. Donations tested for anti-core antibody, and if the donation is repeatedly reactive ‑‑ and it's the first time that that has been observed ‑‑ the products are discarded, but the donor remains eligible for repeat donation.
If the donor comes back and is again repeat reactive for anti-core antibody, the products are discarded and the donor is deferred. And the challenge is to identify a reentry algorithm that maximizes the recovery of those donors without posing any risk.
So this is the same reentry algorithm that has been described already today. The idea is to obtain a followup sample and test it with either the same or an alternate anti-core assay. If the sample is again repeat reactive, then the donor remains indefinitely deferred.
But if the followup sample is not reactive with the alternate or anti-core assay, then that followup sample would also be subjected to HBV DNA testing with the sensitive NAT assay. And if the NAT test is reactive, the donor would be ‑‑ remain deferred. If the NAT test is non-reactive, the donor could be reentered.
And the required sensitivity that has been proposed is less than 10 copies per mL. So now I want to talk about the COBAS AmpliScreen HBV test, which is currently under review. The test has two sample preparation methods ‑‑ a standard method which is used for individual samples and has a 200-microliter sample input, and that has a sensitivity that is a 95 percent limit of detection at 16 international units per mL, which is about 80 copies.
And then, the MultiPrep method, which is used for pooled samples, which has a larger sample input of one mL, and uses a high-speed centrifugation step, to concentrate the virus. And then, after that, the steps are essentially the same as the standard specimen preparation method. And that has a more sensitive limit of detection at 4.4 international units per mL, which is about 22 copies, which is still not as sensitive as the proposed requirement for using that in a reentry algorithm.
So what we tried to do is identify a method to lower the 95 percent limit of detection to under 10 copies per mL, with minimal procedural changes.
So at such low titers, the sensitivity of a test is significantly affected by the limitations of sampling. So if you take a one mL sample that might have three detectable DNA molecules in it, and apply the MultiPrep procedure, so centrifuge it and then eventually recover the sample in 200 microliters, the PCR test is done on 50 microliters of this material.
So the 50 microliter sample that is tested may not contain any of the targets. So a non-reactive result might be observed, even though there were some targets in the sample. So low titer samples can appear negative, just due to sampling error.
And you can increase the odds of detecting that just by testing more samples. So if we start with the same sample that's recovered in 200 microliters, but then use three aliquots of it into three separate PCR reactions, it's likely that at least one of the three aliquots will contain one of the targets.
So in this cartoon, two of the three aliquots contained the target and were reactive, and the interpretation of the result is that if at least ‑‑ if one or more of the tests are reactive, the sample is positive. And if all tests are negative, then the sample is considered negative.
So we can do some calculations. As I stated, the limit of detection of the test is 4.4 international units per mL. That's the concentration that's detected 95 percent of the time. So using Poisson distribution, one can calculate what the hit rate would be for lower concentrations.
So a 65 percent hit rate, for example, would be observed on a concentration of 2.4 international units per mL, which is about 12 copies per mL. So just looking at the statistics, if one had samples of 12 copies per mL, and did ‑‑ and analyzed one sample and conducted three PCR reactions on it, and considered the result to be positive if at least one of the three were reactive, then the sensitivity would improve from 65 percent to almost 96 percent.
And this just illustrates that the probability of getting a reactive result at 12 copies per mL with the test is 65 percent. So if you just do one test, you can pick it up 65 percent of the time. But if you do two more replicates, then you have a much greater chance.
You have eight possible outcomes. Seven of them are reactive. And if you add up all of the probabilities, you have a 96 percent chance of picking it up, and only a 4 percent chance of missing it.
So we tested these calculations out with the study, and the experimental design was to take the HBV international standard and make dilutions to 30, 10, 3, and 1 copies per mL, and then to do 40 ‑‑ to analyze 40 replicates of each of those levels. And on each replicate one one mL aliquot was extracted, and three PCR reactions were conducted.
So I don't expect you to read this, just look at the colors. These ‑‑ this table shows all ‑‑ the results on all 40 samples at 30 copies per mL, and there's two columns for each replicate. One shows the target result, and one shows the internal control result. But what you should look for is where the red is, so the red indicates a non-reactive result.
So out of the three replicate tests done on the 40 samples there were a few non-reactive results, but all 40 samples had at least one positive result. So the overall cumulative detection rate was 100 percent.
And then, at 10 copies per mL, again, all 40 samples had at least one of the three replicates detected. So the cumulative detection rate at 10 copies per mL was also 100 percent.
At three copies per mL, we're starting to see, again, that the sampling issue prevents many samples from being detected. But 29 out of the 40 still had at least one of the three replicates positive for a cumulative detection rate of 72-1/2 percent.
And at one copy per mL, 10 of the 40 samples had at least one test result positive for an overall detection rate of 25 percent.
So if you take this data and use Probit statistics to determine the 95 percent limit of detection, it would be six copies per mL.
So the conclusion is that using the MultiPrep specimen preparation method on one aliquot per sample, and doing three PCR reactions on each aliquot, and calling a sample positive if one or more of the reactions are reactive, then the cumulative 95 percent limit of detection for the COBA sample screen test is under 10 copies per mL calculated to be six copies per mL.
So if a followup sample from a deferred donor was non-reactive with an alternate anti-HB core test, coupled with a negative test result with a highly sensitive NAT test, this should provide sufficient data to safely reenter donors who were previously deferred.
And I'll be happy to take questions.
ACTING CHAIRMAN ALLEN: Thank you.
DR. HOLLINGER: Yes. I'm just a little confused. Is there ‑‑ why is it that it doesn't work with the 200 microliters? Why don't you just test the 200 microliters which has all the particles in it, instead of doing three replicates? What am I missing here?
DR. HERMAN: The reaction can't accommodate that large a volume. So I can't take the 200 microliters of the extracted sample and put it all into the PCR reaction. The PCR reaction is designed ‑‑ that would be developing a whole new assay.
DR. HOLLINGER: I thought initially you showed that you had looked at 200 microliter samples, though, in the very first slides. And you looked at ‑‑
DR. HERMAN: Oh, no. Let me go back to the ‑‑ we have two different sample preparation methods ‑‑ one that uses one mL plasma, and it's a more sensitive method but it's less convenient because it requires this high-speed centrifugation step. And when you do the high-speed centrifugation step, and then extract the pallet, the pallet ‑‑ the recovered ‑‑ DNA is eventually recovered in 200 microliters of an assay reagent with specimen diluent.
And then, 50 microliters of this material can be brought into PCR reaction. Regardless ‑‑ and with the standard sample preparation method, one starts with 200 microliters of sample, skips the centrifugation step, and just extracts that whole volume. But that still gets recovered in 200 microliters of specimen diluent.
With both methods you end up with a recovered DNA in 200 microliters, and only one-fourth of it ‑‑ 50 microliters ‑‑ can get into the PCR reaction.
Does that clear it up? Maybe ‑‑
DR. HOLLINGER: Thank you.
DR. HERMAN: We have things that we've thought about to do large volume PCR reactions. With infectious disease testing, the ‑‑ one of the main limitations is, how much sample can you get into a test? And one way of doing that is to make better sample processing methods that can concentrate big plasma samples into very small volumes, and there are many factors that limit that.
And the other is to make a really giant PCR reaction, and there are factors that limit that also.
DR. HOLLINGER: Just for information, how fast are you spinning this down?
DR. HERMAN: It's 23-1/2 thousand G's, I believe.
DR. HOLLINGER: For just an hour?
DR. HERMAN: For an hour.
DR. HOLLINGER: And that's in serum?
DR. HERMAN: That's in plasma.
DR. HOLLINGER: I mean, plasma.
DR. HERMAN: It doesn't pallet 100 percent of all the virus particles.
ACTING CHAIRMAN ALLEN: Other questions or comments?
Okay. Thank you very much, Dr. Herman.
The schedule now has us moving to our open session. We're going to actually modify our agenda very slightly. Earlier this morning we did not have the presentation of plaques and recognition of the BPAC members who are ‑‑ for whom this is the last formal meeting, let me put it that way, and we will do that now.
We will then have a break of 15 minutes and come back and move into our open hearing.
So, Dr. Epstein.
DR. EPSTEIN: Well, this is always a bittersweet moment at our Advisory Committee meetings. On the one hand, it's a very special privilege to be able to thank our BPAC members for their service to the committee and to the FDA, but, obviously, it's a sad moment when we have to ask those people to step down because they've completed a term of service.
We value greatly the advice that we receive from the Blood Products Advisory Committee, and we're fully aware that it requires a very special effort to digest the materials that we send to you and to pay close attention during the course of our very detail-oriented meetings.
And so it's my pleasure, my privilege, and with sadness, to thank these specific persons. Dr. Kenrad Nelson, who completed not just a term of service at the last meeting but also his tour as Chairperson; Dr. Jonathan Goldsmith, committee member; Dr. Michael Strong, who has been our member as a ‑‑ the industry representative; and Dr. Charlotte Cunningham-Rundles, also a voting member.
So if each of these people would come up in turn, I'll be happy to award a certificate and a plaque as a token of our appreciation for all your effort on our behalf.
Okay. First, Dr. Nelson.
And did you have the photographer ready? Okay. Notice this spontaneous setting.
Okay. Next, we'd like to thank Dr. Charlotte Cunningham-Rundles.
Okay. Next, we'd like to thank Dr. Jonathan Goldsmith.
Now, Dr. Michael Strong, thank you.
So perhaps one round of applause for everyone together.
So, Jim, do we get our break now?
ACTING CHAIRMAN ALLEN: Yes. We'll take a 20-minute break. Please be back here at, well, 10 minutes after ‑‑ 10 minutes after 11:00.
(Whereupon, the proceedings in the foregoing matter went off the record at 10:50 a.m. and went back on the record at 11:14 a.m.)
DR. SMALLWOOD: We're in countdown mode.
ACTING CHAIRMAN ALLEN: Thank you. We will now move into the open public hearing. Just got new stuff put on my papers here, so I ‑‑ I've got two speakers who want to speak at the ‑‑ on the reentry of anti-HBC donors, Dr. Andrew Heaton and Dr. Steven Kleinman. I need to, first of all, read the open public hearing statement.
Both the Food and Drug Administration and the public believe in a transparent process for information-gathering and decision-making. To ensure such transparency at the open public hearing session of the Advisory Committee meeting, FDA believes that it is important to understand the context of an individual's presentation.
For this reason, FDA encourages you, the open public hearing speaker, at the beginning of your written or oral statement, to advise the committee of any financial relationship that you may have with any company or any group that is likely to be impacted by the topic of this meeting.
For example, the financial information may include the company's or group's payment of your travel, lodging, or other expenses, in connection with your attendance at the meeting. Likewise, FDA encourages you at the beginning of your statement to advise the committee if you do not have any such financial relationships.
If you choose not to address this issue of financial relationships at the beginning of your statement, it will not preclude you from speaking.
Okay. Dr. Kleinman, may I call on you first, please, to present a combined statement from AABB, ABC, and ARC.
DR. KLEINMAN: Hi, and good morning again. The AABB and other blood banking organizations have been working with FDA over the last several years to develop an algorithm for reentry of donors who have been deferred due to reactive anti-HBC results.
Blood banking organizations believe that the proposed anti-HBC reentry algorithm will be a major benefit to deferred donors, will increase the number of donated units, thereby improving blood availability, and will not compromise blood safety.
AABB, ABC, and ARC support the FDA proposed algorithm and urge BPAC to endorse its use. Approval of this algorithm is only the first step in moving anti-core donor reentry forward. The next step is for manufacturers of HBV NAT assays to work with the transfusion medicine community to design and carry out the necessary studies to establish that their testing system can be used for anti-HBC reentry.
The blood banking organizations are committed to this project and will provide the needed donor specimens. We urge the manufacturers to promptly meet with FDA, so as to devise the appropriate studies to obtain an anti-core reentry claim. Furthermore, we urge the FDA, under its critical path initiative, to encourage HBV NAT assay manufacturers to participate in pursuing this reentry claim.
Another necessary element for anti-core reentry is the availability of an FDA-licensed more specific anti-core assay for routine donor screening. Compared to the non-specific assays used at the end of the 1980s and in the early 1990s, one such assay currently exists, and the data suggest that another core assay currently under FDA review may have even greater specificity, thus potentially increasing the yield of donors who could be reentered.
It is the goal of the majority of blood collection agencies to move forward with anti-core donor reentry soon after licensure the implementation of the PRISM anti-core assay, provided that one or more HBV NAT tests are approve for this purpose.
AABB, ABC, and ARC believe that there is widespread consensus that anti-core reentry will be beneficial to deferred donors and to the blood system and urge that all involved parties find a way to expedite its approval and use.
ACTING CHAIRMAN ALLEN: Thank you, Dr. Kleinman.
Any questions or comments pertinent to Dr. Kleinman's presentation?
Okay. Dr. Heaton.
DR. HEATON: GEMProbe, Incorporated and Karon Corporation have submitted a biologics license application for the procleics ultria blood screening assay to the U.S. FDA on September 29th. Both Karon and GEMProbe do support the FDA request for BPAC advice on a reentry algorithm for the application of HBV nucleic acid testing to allow reentry of donors previously deferred for HB core antibody serology tests.
Specifically, and in addition, Karon and GEMProbe also support the AABB proposal for a validation study of 3,000 recalled anti-HB core deferred donors as a means to establish HPB NAT as a required component in an anti-HPC deferred donor reentry algorithm. The companies fully support the transfusion medicine community in their desire to pursue HB core reentry.
ACTING CHAIRMAN ALLEN: Questions for Dr. Heaton?
Okay. Thank you.
Are there any other comments that anybody wants to make during the open public hearing?
Okay. We will close the open public hearing and move to the committee discussion. This was stated to be ‑‑ or the next presentation was the FDA perspective and questions for the committee. I understand that, in fact, there will not be formal questions for us to discuss. But Dr. Kaplan will present the FDA perspective at this point.
DR. KAPLAN: Okay. So what you have heard is that we have a ‑‑ we're proposing an algorithm, or the Blood Committee is proposing an algorithm to reentry repeat reactive anti-core donors. This algorithm, at the current time, cannot be validated because two big elements ‑‑ mainly one big element is missing, is that the testing with a more specific anti-core test of ‑‑ it's not available.
Sue Stramer mentioned that she is conducting a trial, and that she ‑‑ she's in the process of collecting that data. So basically we don't have formal ‑‑ as the Chairman said, we don't have formal questions for the committee. However, we would like the committee to ‑‑ if they have any comments on the proposed algorithm, if they can do so.
ACTING CHAIRMAN ALLEN: Okay. I guess we don't have a slide or a piece of paper that shows the formal algorithm. Well, we've got lots of paper. We don't have a ‑‑
‑‑ slide that shows the formal algorithm.
DR. KAPLAN: Yes. Let me see if I can pull it forward.
ACTING CHAIRMAN ALLEN: Okay. You know, we certainly heard a lot of data presented by blood collection organizations. We have statements from the organizations themselves in terms of the way in which they would like to see this proceed. I think we've got lots that we can discuss and provide guidance to the FDA in terms of its moving forward on this process, even in the absence of specific questions.
So with that as background, let me open the floor to discussions, questions, comments, or whatever, on the issue before us of reentry of donors that test repeatedly reactive for anti-core.
Jonathan. Dr. Goldsmith.
DR. GOLDSMITH: I was just trying to figure out about the impact of this whole system. Have any of the blood collectors surveyed these donors who were deferred to learn if they would actually come back as donors again if they were reentered through some kind of algorithm?
Do we have any information about that? Or are these people who have had a test, it came back negative from their point of view, and, therefore, they are going to drop out of the blood donor pool from that point forward? Do we have any information about these people? Have they been surveyed?
ACTING CHAIRMAN ALLEN: And I would add to that, I would be interested, in particular, from, you know, the Red Cross' perspective what has been ‑‑ I mean, certainly, in looking at the data that Dr. Stramer presented we see a much lower return rate by those donors that received that letter. Even though they're invited to come back in eight weeks, we I think saw a much lower return rate than was true for donors who didn't get any letter of notification.
And I will just throw it open. Are there any representatives from blood collection agencies that would like to address the question that Dr. Goldsmith raised?
DR. KLEINMAN: Yes. I don't have a good answer to your question. I don't think that that specific type of survey has been done for anti-core positive donors. I was going to relate a similar phenomena, though, and that is for ATL deferrals that occurred prior to the change of criteria.
Centers have tried to access donors who were deferred for ALT and reinstate them, since there is no longer a deferral criteria. And I think the yield has been ‑‑ and I don't have any numbers, but I think anecdotally the yield has been reasonably satisfactory, whatever that means.
I mean, the centers who do it say that they find it a worthwhile process, but we don't have the actual numbers to help you there.
DR. STRAMER: Regarding a survey for anti-core, we don't have that. And for ALT, for reinstatement, I don't have the numbers off the top of my head. But we did see higher rates for those donors that were more recently deferred. The numbers that I do have are for P24 antigen in which we did do reinstatement, and about 30 percent of the repeat reactive donors who were eligible for reinstatement did return and were successfully reinstated. So for P24 antigen it was about 30 percent.
But those ‑‑ that was automatic or more proactive reinstatement closer to the time of their next donation. So the question is these long-term deferred anti-core donors, what would be our success of getting those back?
But, again, as I said, if we don't do this for anti-core, then we might as well not do reentry for other ‑‑ any other marker, because this is clearly the highest marker of why we defer donors for test results. And we hear from donors ‑‑ I alone hear from donors every single day about, how can they be reentered for HIV, HCV, HBV? So it's definitely something that the community or these committed donors want.
ACTING CHAIRMAN ALLEN: Dr. Nelson.
DR. NELSON: Yes. It seems to me that beyond the numbers of donors that could be captured or reentered, the benefit ‑‑ there would be a benefit to an individual person to know that, in fact, the test was false positive, the initial screening test, and that he doesn't have a chronic infection ‑‑ an infection with a chronic infection, viral infection. So I would think there would be some benefit to that.
And probably if the blood bank didn't do it, if a person is asymptomatic, probably nobody else would. I doubt his physician would do that. So I can see some benefit to the individual person who was repeated reactive on the core antibody alone. And it seems to me there would be some individual donor benefit from that.
ACTING CHAIRMAN ALLEN: I certainly agree. And, in fact, the availability of more specific tests probably could allow a total reexamination of the testing scheme, which tests are used, and in what sequence, quite apart from the reentry issue.
Dr. Fitzpatrick, do you want to introduce yourself formally, please?
DR. FITZPATRICK: Mike Fitzpatrick from America's Blood Centers. Two things. One is it's very hard to measure the impact of reentry of anything. And it's hard to measure the impact of the deferred donors on other donors who have been deferred for some reason.
But the thing that I would suggest is that this would be the first step toward the next step, which is a supplemental algorithm to core testing that would allow us to use a battery of tests, whether it's NAT or a more specific ‑‑ more sensitive core, to evaluate those initial repeat reactive tests and not have that initial deferral.
And so if we don't have the initial deferral on a new donor, we don't have to worry about reentry, and we're not deferring donors who are eligible to donate. So I would see this as a first step in the progression toward accumulating more information about the tests available and the results available, so that we can come up with an algorithm for supplemental testing that will allow us to not defer those individuals who shouldn't be deferred.
ACTING CHAIRMAN ALLEN: Thank you.
Any questions or comments on that?
DR. SAYERS: My name is Merlin Sayers, and I'm CEO at Carter Bloodcare, which is the community independent blood program for Dallas/Ft. Worth.
Dr. Allen, this will be an acronym-free statement.
I'd like to applaud the FDA for taking this approach to donor reentry. And without wanting to downplay the importance of the question that prompted these comments from the floor, it's not just the yield of a reentry program that's important.
One of the issues that we are dealing with is increasing incredulity on the part of donors who perceive that their donor deferral flies in the face of their own self-assessment of good health. And this is particularly true with regards to core antibody deferral.
These donors who dispute why they might have been deferred, if we cannot confirm to them that the reason they are deferred is because there is genuine risk to their health, these individuals essentially have become disincentives to others in the community when the deferred donors, particularly these core antibody deferred donors relate their experience to friends, family members, and neighbors, saying that they have indeed been deferred.
But during the deferral process, we do not have anything really beyond the precautionary principle to invoke to explain to them what the dual core deferral might mean to their good health. Reentry of these individuals, even individuals who might have been deferred 10 or 15 years ago, is going, to a significant extent, enable us to restore credibility in the minds of deferred donors, and I hope reduce the likelihood that their experience is going to act as a disincentive to other would-be donors.
So we do applaud the possibility of reentry for this particular group of deferred individuals.
ACTING CHAIRMAN ALLEN: Thank you. I think the point that you make is extremely important, and along with that ‑‑ with the comment from Dr. Fitzpatrick, about perhaps with the right evaluation, with new tests, we may never need to send out that letter of deferral initially, or the letter of ‑‑ "There is something that's not quite right in your testing mechanism. Please come back and donate again, so we can retest you."
You know, the point being that if you take healthy people with tests that have less than 100 percent sensitivity, and less than 100 percent specificity, you are going to have some inaccurate test results. The specificity being ‑‑ for a perfectly health donor being the most important measure there.
And our donors are supposed to be a totally healthy population. So it ‑‑ it really is an important issue in terms of the message that is given to them about their health.
DR. KLEINMAN: Yes. One other aspect moving forward ‑‑ and that follows up on these comments ‑‑ is that when we do go to a new anti-core test, hopefully it will be more specific and the people that we defer really will have anti-core. But we still may have some false positives, even on a new test. So I think if we have a reentry algorithm in place, it permits our donor notification message to make more sense.
We can say to people, "We don't know" ‑‑ you have these results, and if you want to check them out further, if you're concerned, you can come back and potentially" ‑‑ and this is for the newly-identified people, you can potentially be reentered.
Now, we may not be able to reenter many of those, but we could get a bad lot of reagent, for example, and wind up deferring persons for an anti-core test result that doesn't reproduce in the future. So I think just moving forward it gives us the ability to notify donors, and that issue that always comes up, "Well, if I'm okay, why can't I donate?"
And we never have an answer for it, and it creates cognitive dissidence in people's minds. "They are telling me I'm okay, but they're telling me I can't donate. That means they don't really think I'm okay. They just sort of think I'm kind of okay."
And by at least offering people reentry you can say, "We have a way of knowing ‑‑ we have a way of coming back to you and giving you further information." And I think that's valuable in the notification message also, psychologically valuable for donors, that we've gone the extra step.
ACTING CHAIRMAN ALLEN: Yes.
DR. SCHREIBER: I guess I'm a little bit confused, because when we're talking about reentry, we're only talking about reentry of the people who were deferred, and, therefore, had two subsequent repeat reactive tests and different donations.
80 percent of those, as Sue indicated, will ‑‑ that have the first repeat reactive will never show up again in the door. So they will never be deferred for hepatitis B tests. So whatever you put out, they will never get a message letting them know what their true status of infectivity is, because they will never come back to the blood center, unless you go through some process to rerecruit those.
Sue's data showed that of those 20 percent of first-time donors that came in, 88 percent were ‑‑ were repeatedly reactive a second time. So those are the people who are deferred. And then ‑‑
DR. KLEINMAN: And that's with the current test, because you had ‑‑
DR. SCHREIBER: Right, right. But still ‑‑ you're still going to have a significant number of people, unless you really drive that false positivity rate way down that are not going to be told to come back and be retested.
I guess the other question I had is that when we talk about this reentry algorithm, and it seems that it's been deferred because there is not a more sensitive core antibody test, what about all of those people that are still out there?
And if we really are talking about a reentry algorithm, why wouldn't we institute it now, because that test is really dependent on the subsequent NAT and other test followup. And the chance that they would get a second or a third ‑‑ a third core antibody test would probably be really, really small at this point.
ACTING CHAIRMAN ALLEN: Dr. Kleinman, are you responding to ‑‑
DR. KLEINMAN: Yes. I just wanted to clarify that. Maybe we didn't state it strongly enough. For reentry to really work, you have to have a licensed, more specific test that the blood center switches to. And without trying to promote or detract from any companies, we do believe that the Abbott PRISM assay is that more specific test, we do think that most Abbott users will switch to that test once it's licensed. And we do believe that the false positivity rate will go down.
But, I mean if you had a reentry algorithm and you're using the same test you used before, it's quite ‑‑ I mean, it wouldn't make sense, because you're still going to be repeatedly reactive on that non-specific test. Most people who are repeatedly reactive are repeatedly reactive to that test over time. They don't ‑‑ it doesn't go away. It's not a one-time thing.
So, really, we need that new test, and, you know, it's been under consideration at FDA for quite a while, and hopefully it will be licensed at some point. And then, at that point, once test centers are using it, then reentry hopefully, if we validated the NAT assays and have the claims, then it might be a practical thing to do. But without that new assay, it's unlikely that reentry would have as good a yield as we would hope.
I don't know if that clarifies it a little bit.
ACTING CHAIRMAN ALLEN: Dr. Epstein.
DR. EPSTEIN: Yes. You know, I think what would be helpful to the FDA is if the committee members would comment specifically on the elements of the proposed algorithm and their scientific validity. And they are posted here on the slide that Dr. Kaplan put up, but just to highlight it it's the idea of an eight-week delay. That's to allow, you know, full-blown development of markers.
It's the idea of an offline test. In other words, you don't collect a unit that might be at risk before you've resolved the status. It's the idea of hepatitis B done on the individual sample ‑‑ in other words, ID NAT ‑‑ but with a sensitivity of at least 10 copies per mL. And I think you've heard that that's hard to reach, but it is feasible.
And that, you know, some data appeared to have been ‑‑ generated less sensitive assays that, you know, could be debated. And that we have dropped the idea of looking at an anti-HBS as part of the reentry algorithm on account of the vaccine issue, and retaining the concept that you must demonstrate at least some negative anti-core test, whether it's the same assay or a different assay.
It's been explained that it's highly desirable to switch the assay, because if you simply use the same assay over again the likelihood it will be reactive again is very, very high.
So I think it would help us if, you know, there were specific comments on the elements of the algorithm.
ACTING CHAIRMAN ALLEN: Thank you. We will get to that.
DR. KUEHNERT: Yes. I just had a question about how this would work practically. So someone comes in, they're repeat reactive the first time, under this algorithm they would not get any kind of a letter or indication that they have a positive test. Is that right? Or are they going to have some indication that they have a positive test the first time but can donate?
ACTING CHAIRMAN ALLEN: Dr. Kaplan, do you want to address that question?
DR. KAPLAN: Yes. So, basically, a person will be repeat reactive on any test, and then it will be deferred about eight weeks, and then it will be asked to ‑‑ a new sample will be collected. And so it will be again tested for surface anti-core and NAT.
DR. KUEHNERT: So they would be asked to come ‑‑ I guess I'm a little confused. So they'd be ‑‑ they'd get a letter saying that they have a positive test, and they need to come back for testing, or it would be when they come back to donate?
DR. KAPLAN: Well, this would have to be a testing at eight weeks, because they were reactive twice and ‑‑
DR. NELSON: The person has already been tested twice and found to be anti-core positive. So under the current algorithm, they are permanently deferred.
DR. KUEHNERT: Right.
DR. NELSON: And I guess what this is, it's a ‑‑ it's to try to reenter those people are permanently deferred because the feeling is that a lot of permanently deferred ‑‑
DR. KUEHNERT: I understand that. I'm just saying, subsequent now to this, not thinking about people who have already been deferred, but people who in the future then are repeat reactive to anti-hep B core ‑‑
DR. KAPLAN: Okay. Basically, we are not right now talking about in the future, what will happen with a future license test. And that's something we are developing and we are thinking about it. However ‑‑
DR. KUEHNERT: But that will apply. If you change this algorithm, that will apply to them as well, won't it? What am I not understanding?
DR. KAPLAN: Yes. Robin wants to comment on this.
DR. BISWAS: Robin Biswas, FDA. This after somebody is repeat reactive on the initial ‑‑ initially. They wouldn't be deferred at that point. You know, the unit, of course, would not be used. The person could return and donate. I think that the blood organizations said that they do get a letter, in fact.
ACTING CHAIRMAN ALLEN: The Red Cross does send out a letter ‑‑
DR. BISWAS: Right.
ACTING CHAIRMAN ALLEN: ‑‑ after the first repeat reactive that invites the donor to come back in.
Dr. Stramer, do you want to clarify that?
DR. STRAMER: First-time core reactives are not deferred. It's up to the blood center ‑‑ well, clearly, the policies of two times deferral are up to the blood center. As Steve mentioned earlier, some blood centers will defer after the first time core reactive, because the yield on the second time is so low.
Some blood centers do the two times deferral policy and don't notify after the first time core deferral ‑‑ I mean, the first time core reactive and just let the donors come back and only notify them based on the second deferral.
We do notify after the first-time deferral for the reasons that these donors truly could be hepatitis B, in fact, and we believe it's the right thing to do. But they still can come back a second time.
So did I help clarify that?
DR. KUEHNERT: Sort of. I mean, what I'm asking, if this gets put into place now ‑‑
DR. STRAMER: Would that change?
DR. KUEHNERT: Yes, right. That's what I'm asking.
DR. STRAMER: Okay. I don't think the question on the table is whether the two-time core deferral policy will change. I think the question just is for those donors who have been core reactive two times, can they be reentered using the algorithm that the FDA proposes.
DR. KUEHNERT: That is correct. I know other people ‑‑ it will just be explained to them that this was a false positive test, and that now they can donate?
DR. KAPLAN: Well, the following slide ‑‑ it's basically at this point people will be told that they can donate, come back, they're negative, and then they will be tested again on the donation. And if it's negative, everything is fine. They can donate if everything is negative.
So I don't know if you can put the next slide ‑‑
DR. NELSON: Do you have an estimate of what proportion of the people who were twice positive will qualify under this?
DR. KAPLAN: No. Because we don't have to ‑‑ we haven't seen the data yet with the PRISM, and that's what Sue Stramer's data was ‑‑ would fill that blank, and then let us know how ‑‑ fully validate this algorithm.
ACTING CHAIRMAN ALLEN: We've got several hands up. Dr. Strong, and then Dr. Doppelt.
DR. STRONG: We don't have good data on that. However, if you go back to the ‑‑ several years ago when the PRISM clinical trials were being done, comparing current license tests with the clinical trial results, there was about a 10-fold improvement in specificity. So it could ‑‑ that's what got everybody excited about the possibility that these donors could be recovered.
ACTING CHAIRMAN ALLEN: Mr. Doppelt.
DR. DOPPELT: I was just going to say I ‑‑ I thought I had it straight. Now I'm ‑‑ perhaps I'm confused. But in terms of fairness to the potential donor, it seems to be there's a difference between whether you say come back a third time and we're going to retest you, to see if you can be a donor, versus come back a third time and we're going to do some different tests and try and sort out whether or not you really have an ‑‑ you're really infectious or not.
So I'm a little bit confused as to what information is going to be specifically relayed to the potential donors.
ACTING CHAIRMAN ALLEN: I think that's an important question to answer. And my guess is based on what we've already heard from different blood collection centers today that since there isn't any single way of handling that first time, that this is an issue that needs to either be clarified by the FDA or to allow the marketplace to sort it out on its own as currently has happened.
DR. DOPPELT: I mean, it just seems to me that you are far more likely to get patients to return if you tell them there is some additional testing that may be done to help sort this out versus come on back and try it again and let's see what happens.
DR. KLEIN: In the proposed FDA algorithm, they are going to do a NAT test that's quite sensitive. So they are, in fact, going to be doing something different.
ACTING CHAIRMAN ALLEN: Right. And one might, you know, raise the question ‑‑ and I'm sure there aren't data there to answer that today, but one might raise the question, if you've got a donor who is repeatedly reactive the first time, if you want to give them the best possible information, maybe you ought to take, you know ‑‑ take the samples from that first donation and subject them to these additional tests instead of asking them to come back in eight weeks.
And I understand the reason for ‑‑ you know, for the eight-week or longer delay in terms of trying to find out if there's progression of markers over time that might indicate real infection, but if you want ‑‑ you know, if you want to give the most reassuring message back to the donor the first time, you would do that before you contact them the first time.
So, you know, I think there's a lot of permutations here that aren't really on the table and haven't been discussed.
DR. KLEIN: Yes, I ‑‑ just to move this a little forward I hope, I'd like to support the concepts of the FDA algorithm. I think it's a good one, and I certainly support reentry for those people who have been deferred because of a two-time causative core antibody test.
At the same time, I'd also certainly like to encourage you to do whatever is possible to get a more specific core antibody test available, and also keep an open mind to the possibility of having an algorithm that will prevent us having to defer such donors in the first place.
ACTING CHAIRMAN ALLEN: Thank you for that statement.
DR. STRONG: Actually, I was going to support his proposal. I think we ‑‑ we have lots of ‑‑ we have lots of donors who get that message by letter. The letters are constructed in different ways, so the recipient may get a different message than was intended. But many of them at least will be told that they should see a physician, and they go to a physician and they get tested and it's negative, because they're using different tests.
So I think also to accelerate the discussion that we've probably heard enough, and I would certainly support it.
ACTING CHAIRMAN ALLEN: Yes. Dr. Hollinger.
DR. HOLLINGER: Again, I support this statement. I think it's a good statement. You might ask the question, you know, even when you look up, there will ‑‑ why even have to do ‑‑ I mean, if you have a test, a new test, let's say, that's licensed, that is completely specific, then why do you even have to do HBV NAT in these patients?
And it goes back to the other issue is ‑‑ what has been taught by the blood bank a lot, and others here, is that it's important to tell those donors who do not have an infection, or do not have any evidence of exposure, that they're clear of this disease. I mean, there's nothing really there.
But I ‑‑ I also want to say that the blood bank does the clinicians a great service in this regard, because it also tells those who may be infected that this is an issue. So we've talked so much about the ones who may be falsely positive, and what it's going to do by telling them and talking to them about this issue.
It's just as equally important to talk to those who have a positive result of whether they might be infected, and that's where the HBV NAT comes in. And by looking at all of the things ‑‑ one of the things I like about getting information from the blood bank is that they are willing to send to clinicians all the information ‑‑ the cutoff levels, which I like to look at, the ALT levels, which are often ‑‑ when they were doing them, which is also ‑‑ can be elevated, and yet the patient ‑‑ the donor can contribute. It could be a variety of things.
But all of that information is really helpful when you then can sit down with a person, and certainly by looking at this, then I could say to that person, "Look, I see no evidence that you have an active infection here. Even if it's a very specific positive anti-HBC test that's highly ‑‑ that has a high titer, or high concentration of the antibody," and the HBV NAT is negative.
Then I might be able to tell them that and reassure them that I see nothing in these studies that would have me concerned. I don't mind telling them that they're not infected. It's not a real issue at that point. And if they're positive, then one can deal with that issue also and reassure them about their risks, and so on, for transmission and other things which are usually very small.
ACTING CHAIRMAN ALLEN: Thank you.
Dr. Bianco, first of all, if you'll introduce yourself, and then Dr. Biswas.
DR. BIANCO: Celso Bianco, America's Blood Centers. I want to make two quick comments. One is the reason why only old people remember that plain ‑‑ the reason why we do it twice in terms of only deferring on the second time is from day one we recognized that this is a lousy test, in terms of specificity. And we were hoping that we could recover some donors. Hopefully, a new test, more specific, we will be able to do it only once and make a conclusion about that. We don't need to wait for two.
The second point that I'd like to make is addressing one of the questions that Dr. Kaplan has asked us, and Dr. Epstein, is the question of offline testing. I think I'd like very much to discuss that. It appears that it's a note of caution that you will call back the donor, collect only a sample, and then, after getting the results on that sample, you will allow the collecting of blood units.
Donors, unless they are very angry with us, and they come together with a bill from their doctor for all the tests that they did because of our core positive doctor, and they want the blood center to reimburse them for that, they don't come back just for a test. They come back for a blood donation. That's what attracts them is their sense of altruism, sense of trying to help.
And so the chances, I believe, of releasing a unit inappropriately because of a test result are very small. Usually units are released inappropriately when it happens. Because of other issues, they are not so much dependent on the interaction, direct interface between testing machines, computers, and the computers that release the unit of blood.
So I would ask that these requirements be dropped.
ACTING CHAIRMAN ALLEN: Dr. Epstein first.
DR. EPSTEIN: Well, I think the other side of that argument needs to be heard, which is that there is a finite risk of inadvertent/inappropriate release of a unit, and the risk of consequences goes up if that is, in fact, an at-risk unit.
So that's why in our reentry algorithms we have always wanted to requalify the donor offline, because otherwise you've drawn an at-risk unit, you don't know its status yet, it might turn out to be true positive, and there's a finite risk unrelated to the testing that it might get out.
ACTING CHAIRMAN ALLEN: Dr. Klein.
DR. KLEIN: I'm not sure that those data are correct, Dr. Bianco. We've never had any difficulty getting people back for our studies just to be tested. And, in fact, we've found that people are more reluctant to give a unit that they think might be discarded, so I don't know of any data to say that they won't come back to be tested. Our experience is exactly the opposite.
ACTING CHAIRMAN ALLEN: Dr. Kuehnert, and then Dr. Biswas.
DR. KUEHNERT: I just wanted to say that I'm supportive of the statement. I think, you know, this is probably going to apply to a very small number of people, at least the way the tests are currently applied. And I do have concerns about sort of donor counseling and health, but that's not at issue here.
I think it could be a good topic for another government committee, but, you know, just with that in mind I think donor health is important. And I think there is some work to be done here. There's probably going to be more confusion when the new algorithm is applied initially concerning counseling, but overall I think this is a good statement.
ACTING CHAIRMAN ALLEN: Dr. Biswas.
DR. BISWAS: I just wanted to say, you know, there's been a lot of talk, which I agree with you, about the specificity, lack of it, and, you know, the importance of having a specific anti-core test. But remember that the reason we are bringing this issue to you at this time is because of the improvement or the development of NAT technology, and that really was the driving force here. I just wanted to say that.
ACTING CHAIRMAN ALLEN: Dr. Busch.
DR. BUSCH: Yes, I want to address the issue of the NAT sensitivity requirement. The only donors who will be reinstatable will have to be negative on test of records ‑‑ surface antigen anti-core assays. In fact, these donors, if they came in for the first time today, they wouldn't be screened out at all. They were the historical false positive anti-cores.
We know in true anti-core positives that are persistently anti-core reactive on all the assays, if you progressively increase the sensitivity of your NAT test, you will cull in a little bit more, you'll detect a smaller incremental fraction of very low viremic donors.
So the studies that we've done and Sue described where if you go from 100 copy to 50 copy to 10 copy sensitivity, you pick up a small fraction of additional low viremic carriage, but this is in people who are fully seroreactive and would be reactive on any anti-core test.
And, you know, the requirement for 10 copy, 95 percent hit rate is making all the companies have to do multiple replicates ‑‑ would make the NAT screening cumbersome for the blood centers even if these tests can achieve that level of sensitivity.
And I just don't understand where that number came from and why FDA is pushing such an extremely stringent low sensitivity threshold when, again, these donors would be eligible today. And in the absence of any NAT screening right now, and certainly once NAT is in place, it will be likely done on small pools, and certainly not with assays that have this level of sensitivity.
ACTING CHAIRMAN ALLEN: Would anybody like to respond to Dr. Busch's comment?
DR. BISWAS: Mike, I think you were asking ‑‑ I didn't hear everything you said, but your questioning the ‑‑ the requirement for 10 copies and less, that was it. I should say that ‑‑ actually, Dr. Kaplan did say it earlier ‑‑ that we are sort of flexible on that point. It will depend on some of the results ‑‑ on the results that we get back using the less sensitive test that Sue Stramer is doing with NGI.
And it ‑‑ but I should say that although it is stringent, it does seem to be as though it is possible. But as I said, we would be flexible and will take into account the clinical trials ‑‑ the results of the trials that are being done under IND, and that we are flexible on that.
ACTING CHAIRMAN ALLEN: Dr. Kaplan, did you want to respond?
DR. KAPLAN: Yes. You know, someone was deferred ‑‑ gave twice anti-core, it was repeat reactive anti-core, so this ‑‑ there's some flag there. It could be ‑‑ you know, it could be a false positive measurement, but there's a flag there. So there's some rationale there to try to increase the sensitivity of the NAT. And as we heard from Roche, that's achievable.
And then, so what ‑‑ what you don't want to do is someone that's ‑‑ you know, has a very low core and a very ‑‑ a very low DNA, but it could be an infectious unit to ‑‑ to reenter it. So there's some rationale for asking the state-of-the-art sensitivity, maximum sensitivity achievable.
ACTING CHAIRMAN ALLEN: Dr. Lew.
DR. LEW: I think I heard pretty well that, you know, for those who are ‑‑ and someone can correct me ‑‑ anti-core antibody positive alone, but if you keep on going down, you know, might detect real, real low levels, and for our immunocompetent patient it's quite possible these patients will not become infected.
But since a lot of our blood products go to immunocompromised patients, and they get a lot of blood products, I'm not hearing that potentially, you know, these ‑‑ if these patients do get it, that they will become positive. They will get infection. So I'm a little concerned about those patients and how this algorithm works.
ACTING CHAIRMAN ALLEN: I think that's a very important and interesting comment.
DR. HOLLINGER: I think part of it comes back to we need to know how many of the ‑‑ these new licensed tests might be negative when the other test is positive, and that we need to know the false negative rate, if any, of the ‑‑ of HBV DNA in those samples.
If not, then it ‑‑ then I don't think that's ‑‑ if it's not there, and I suspect it may not be, then they're not at risk. I don't think they would be at risk in a ‑‑ with a good assay that's very specific. And if it's given to an immunocompromised individual, if there's no virus in the blood, or detectable virus, then those patients are not going to get ‑‑
DR. KAPLAN: Can I add something? It's that this algorithm that you have the donor tested at least three times, you know, it was ‑‑ all markers negative, but it was repeat reactive, then you bring it ‑‑ bring them back at eight weeks, and then you test them with all the battery again. And then, if they are negative, they are ‑‑ then you have a donation.
So, you know, if it's low levels, you should ‑‑ you should be able to detect it at that time. I think that's a pretty well functional algorithm.
ACTING CHAIRMAN ALLEN: Dr. Lew, and then Dr. Strong.
DR. LEW: No, I don't really have a problem with this algorithm. I'm just talking ‑‑ hearing the conversation of other methods of how to decide. And as far as I'm aware, I don't know if there's any lab test that I know of that's 100 percent sensitive-specific. You know, I'd keel over if there ever was one.
DR. STRONG: But I think the point is that it won't be worse than it is now, because the new tests are actually both more specific and more sensitive. So, if anything, we're going to catch more.
ACTING CHAIRMAN ALLEN: Dr. Kleinman.
DR. KLEINMAN: Yes. I just wanted to emphasize, I think the issue of reentering somebody is dependent on the sensitivity of the tests you use to reenter. And remember, the reentry scheme includes two tests, three tests actually ‑‑ surface antigen as well. But it includes another anti-core test.
So if you are positive on that anti-core test by a second manufacturer, you're out. It doesn't matter what your HBV NAT test shows. So if that's an equally sensitive test, I mean, if you ‑‑ you're negative on that anti-core test, and that anti-core test is equally or more sensitive than the one you're using, you don't really have anti-core. And, therefore, you wouldn't need any NAT testing.
I mean, it would just be the same as if that person came in today and had never been deferred in the past, and was screened with the new test. They'd be anti-core negative, and you could say, "Well, gee, we might be missing somebody. Maybe we should do HPB NAT testing at 10 copies per mL on every donor in order to increase the safety of the blood supply."
Well, obviously, you're not going to do that. So I think we need to see the clinical trial data that validates the reentry algorithm, and then we'll know if there are discrepancies between ‑‑ if somebody is negative on the new test, and actually has HBV DNA in their serum. If we find somebody like that, how sensitive in that test did we need to do to find that person? Did we need to do a 10 copy mL test? Or was a 50 copy mL test enough? And then we would be able to test ‑‑ to maybe set our sensitivity levels.
Now, I don't know if we could do a big enough clinical trial, because I don't expect we'll have many people who are NAT positive failing the second reentry test. So it does become kind of arbitrary. But I think maybe that's why the FDA is saying there is some flexibility; we just don't have the data to know yet.
But I think, really, to answer the question that's on the floor we ‑‑ we do have protections in place with this algorithm, and even if we were to increase the ‑‑ or I guess decrease the sensitivity of the NAT, increase the copy number of detection, even if we were to do that, I think our patients would be protected from getting unsafe units because of the second core test.
ACTING CHAIRMAN ALLEN: Dr. Stramer.
DR. STRAMER: Yes. Two points, commenting along the same lines that Dr. Strong brought up. As Blaine mentioned in his presentation with the use of reductant in this new, more specific test, it's the use of this chemical treatment that eliminates the false positive non-specific early IGM antibodies that cause interferences or false positivity in the test.
But because of this concern, the test before the FDA has gone through extremely robust validation. And as has been pointed out before by Mike, the test is not only more specific but is actually more sensitive because of the disassembly of all these false positive, non-specific antibodies, so that it's more specific for low-level true antibodies.
So the test is more sensitive, it's more specific, and what FDA is proposing is actually a very robust reentry algorithm. You would use the more sensitive and more specific anti-core test. The donor would not only have to be negative on followup, but then again negative at donation.
And we're kind of quibbling ‑‑ is 10 copy, 50 copy ‑‑ certainly, if you want to increase the catchment, a more sensitive test is what you should do, or to really identify those people who are circulating DNA, from a public health perspective and from a reentry perspective, and there are tests that are ‑‑ you know, that can be achieved.
Whether it's 10 copies or 30 copies, I don't think that makes a difference. I mean, we were ‑‑ when Red Cross presented data to FDA, FDA actually said 30 copies was inadequate. So we moved it down to 10 copies quite arbitrarily, just because if we thought 30 wasn't enough, well, what would be sensitive enough? So we just chose 10 as something that we thought even the FDA wouldn't reject.
So that's kind of the derivation of the 10 copies per mL. But robustness has ben built in the algorithm, and robustness has been built into the tests that are before the FDA for licensure.
ACTING CHAIRMAN ALLEN: I would like ‑‑ okay. Dr. Lew.
DR. LEW: If I could just say that ‑‑ just for ‑‑ I think everyone agrees it's a given, but for clarification, that this statement seems suitable for most people ‑‑ given the caveat, we're talking about a more sensitive hepatitis C core antibody test. I mean, just for that clarification.
ACTING CHAIRMAN ALLEN: Dr. Epstein.
DR. EPSTEIN: I just want to comment on what we know and what we don't. What we know, and these are Sue Stramer's data from the histogram that you showed of viral load, there are indeed samples that have a viral load of 10 copies per mL or less in individuals who have a repeatedly reactive anti-core test, and who ‑‑ 65 percent of whom have a negative HBsAg test.
What we don't know is whether those same samples would be found if a third independent test were negative for anti-core. And we couldn't show you those data because we don't have those data. But no one should think that there are no samples with low-level viremia in individuals with so-called anti-core only by current testing. There are such people.
So the problem here is, you know, can we really place our faith that there won't be any such low-level viremias in those in whom another EIA is negative. We just don't know until we have those data.
So I just don't see ‑‑ but the, you know, proposal that we use assays as sensitive, that is based on the observation that some of the true positives do have DNA at that low level. What we don't know is whether the ones with the further negative EIA would have DNA at that level.
ACTING CHAIRMAN ALLEN: Thank you.
Let me come back to the proposed FDA statement here and just ‑‑ we've heard some ‑‑ actually, all of the committee members that have spoken have spoken in favor of the basic algorithm. What I'd like to do is just ask the committee for any additional comments that anyone might have about the FDA proposed algorithm and issues directly related to that.
DR. QUIROLO: Well, it would seem to me that if this is such a sensitive core test that you wouldn't really need to come back twice to have two ‑‑ a repeat reactive and then a third test, it sounds like, before you did the NAT and the surface antigen again before donation.
The other thing is if this is such a sensitive test, what's the possibility that somebody would come back for their second core test, being reactive the first time, and being negative the second time? And if you're using the same core over and over again, isn't that the same dilemma you're in now where you're ‑‑ if you're reactive once, you're more likely to be reactive over and over again?
DR. KAPLAN: Well, this algorithm basically solves a present problem. And so, you know, Mrs. Stramer ‑‑ through the number of a million people that they could be ‑‑ reenter with this.
I think that the ‑‑ the other issue that you are raising is: what is the performance of this new test that has not been approved? And how will that fill into the ‑‑ this algorithm or the deferral ‑‑ deferred algorithms for repeat reactives in core? It's something we have to see at the moment of approval of that new test. I think that's on the table at this point.
However, we are ‑‑ we agree with ‑‑ I personally agree with what you said is that, yes, that's a very important point that we have to retain ‑‑ or reevaluate when we have this more specific, more sensitive test available. Yes.
ACTING CHAIRMAN ALLEN: In actual fact, if the belief is that most of these people are not truly infected but are false reactives, then, in fact, the issue is not ‑‑ it really doesn't matter how much more sensitive the test is. The question really is needing a test of increased specificity, and the new generation tests coming on the market should meet that.
DR. QUIROLO: Will those be the initial tests, though, for the new donors once the test is available? Will that be ‑‑ will the more sensitive test be the initial test? Or will there be two tests, a less specific and then another second test after you fail the first one?
DR. KAPLAN: We don't know how many people will adopt that. We don't even know when this will be licensed at this point. And I think that's a market force ‑‑ speculation at this moment.
ACTING CHAIRMAN ALLEN: Yes. As you were asking your question, I saw heads nodding around the room from blood collection people.
Dr. Strong, do you want to comment on ‑‑
DR. STRONG: Yes. Once we have a new test that has greater sensitivity and specificity, the old test goes away. We'll only be using one test. And the donor is likely to be deferred, because we fully expect that we're going to be doing DNA as well.
ACTING CHAIRMAN ALLEN: Other specific comments from the committee members on the FDA proposed reentry algorithm? Anybody have major heartburn over it? We basically heard comments in support with a few questions on technical details.
Okay. I would like to add my support to the basic proposal, and, you know, would encourage, based on all that I've heard today, I would encourage the FDA to continue working to get this completed as rapidly as possible.
Does the committee ‑‑ and this is a straw vote ‑‑ does the committee believe that this needs to come back to the committee again once as a formal question, or have we given sufficient direction to the FDA and would like to encourage them to move forward as rapidly as possible to implement?
DR. EPSTEIN: Jim, if I could just clarify, that, you know, the committee serves to advise us on the science. You know, FDA takes unto itself the responsibility of determining the policy. So in phrasing your question, really, is ‑‑ the question is: are there other scientific issues that need to be brought back to the committee?
ACTING CHAIRMAN ALLEN: Thank you. Yes, that was what I meant.
DR. KUEHNERT: I just wanted to ask if there ‑‑ there was some discussion about the sensitivity level required, if that's a ‑‑ still an open question, or has FDA gotten enough guidance on that issue?
DR. EPSTEIN: Well, our position is that we want to see the data that emerge from combining historic, you know, twice anti-core repeat reactives with negative results of a more sensitive and specific screen, and then see: a) if there are any DNA positives, and b) what their levels are. But we think that those studies need to be done with the most sensitive available assay, otherwise we'll never get a meaningful answer.
So I can't answer the question on point. I can only answer it by saying this is why we want to see the studies that we describe.
DR. KUEHNERT: And I think, you know, the discussions we've had in previous meetings about mini-pool NAT screening in general, you know, the consensus was for more sensitive screening. So I think this all works towards that.
ACTING CHAIRMAN ALLEN: All right. Any other comments or questions? Does the FDA want further discussion from the committee, or have you achieved what ‑‑ okay.
It's approximately 12:15. The official game clock here says it's 12:21. That's a little faster than my watch, which tends to be one or two minutes fast most of the time. We will adjourn for lunch. Let's plan to have ‑‑ have people back ‑‑ we will reconvene at 1:20 by the game clock here.
(Whereupon, at 12:15 p.m., the proceedings in the foregoing matter recessed for lunch.)
DR. SMALLWOOD: We're ready to reconvene. May I ask all Committee members present to please take your seats, and may I have the attention of the audience?
Before we start, I just wanted to make an announcement. Dr. Martin Ruta this morning mentioned a draft guidance that was expected to be published, and I just wanted to announce publicly that on the FDA web site guidance for industry, use of nucleic acid tests on pooled and individual samples from donors of whole blood and blood components, including source plasma and source leukocytes to adequately and appropriately reduce the risk of transmission of HIV I and HCV has been posted as of this morning. So it is on the FDA web site. Dr. Allen, were you ready? We're ready to reconvene.
ACTING CHAIRMAN ALLEN: Good afternoon. We're ready to continue our discussion with Topic 2, the potential risk of Simian Foamy Virus transmission by blood transfusion. Our first presentation will be the introduction and background by Dr. Tabor.
DR. TABOR: Good afternoon. I'd like to begin by thanking the other speakers who will be participating in this session. Dr. Kahn from Sieber but also people who came from a great distance ‑‑ Dr. Heneine, Dr. Brooks, Dr. Peter Gantz and Dr. Lerka ‑‑ all of whom you'll be hearing from soon.
The potential risk of transmission of Simian Foamy Virus by blood transfusion is being brought to be BPAC at this time because of a report in the Lancet that this retrovirus is being transmitted under so-called natural conditions from non-human primates to the human population in Cameroon. This not only places a renewed focus on Simian Foamy Virus transmission but also represents a mechanism by which Simian Foamy Virus and other non-human primate retroviruses might enter the human population and ultimately the blood supply.
This issue is made more urgent by recent research developments related to the possible transmission of Simian Foamy Virus to non-human primates by blood transfusion, and this information will be presented by the other speakers at this Advisory Committee meeting today. Can I have the next slide, please?
Transmission of Simian Foamy Virus to humans due to occupational exposure to infected non-human primates has been reported to occur in two to five percent of persons working with non-human primates in research institutions and zoos. Most of the infected persons had histories of scratch or bite injuries caused by the non-human primates.
Because of these reports, the topic of Simian Foamy Virus was discussed at the December 13, 2001 BPAC and the consensus of BPAC in 2001 was that more data were needed to determine whether Simian Foamy Virus presented any risk to the safety of blood transfusions. Next slide, please.
This year, in the March 20, 2004 issue of the Lancet, transmission of Simian Foamy Virus to humans by so-called non-occupational contact with non-human primates was reported by Wolfe et al. and was accompanied by a commentary by Peters et al. In fact, the exposure was only somewhat non-occupational in the generally accepted use of the term, "occupational," since the authors felt that the transmission probably occurred as a result of a hunting preparation and consumption of food made from tissues of non-human primates, sometimes referred to as bush meat. Next slide, please.
Wolfe et al. studied 1,099 residents of the tropical forest area of Cameroon who had regular contact with blood or body fluids of non-human primates. Antibodies to Simian Foamy Virus were found in ten persons. Among these ten, Simian Foamy Virus itself was found by RTPCR in the peripheral blood lymphocytes of three. These three apparently had acquired Simian Foamy Virus in three distinctly separate transmissions from non-human primates. The individuals were each from different villages and the nucleotide sequence of each isolate of Simian Foamy Virus showed that the Simian Foamy Virus in each person was from a different primate species, each consistent with that person's individual hunting and food preparation history, enveloping gorilla, mandrill and cercopithecus species, respectively. These observations are consistent with the known fact that the different Simian Foamy Virus strains are each highly specific for their host species. Next slide, please.
Simian Foamy Virus is quite prevalent in the non-human primate populations, ranging from 31 to 61 percent among non-human primates in the wild and from 70 to 90 percent among those in captivity. In contrast, the prevalence of Simian Immunodeficiency Virus among non-human primates in the wild, in the same geographic areas, is about 16 percent, and the prevalence of Simian T-Lymphotropic Virus is about 11 percent.
What is the risk of Simian Foamy Virus becoming widespread among humans once it has entered the human populations. Recent reports by Heneine et al. and Switzer et al. provide strong evidence of persistent Simian Foamy Virus infections in humans, with infections lasting as long as 19 and 26 years or longer. However, human-to-human spread of Simian Foamy Virus has not yet been shown to occur. We do know that the study of a small number of wives evaluated in studies of persons with occupationally acquired Simian Foamy Virus infection has not revealed any instances of spousal transmission. And the low percentage of infected persons working in primate facilities suggests that human-to-human transmission, if it ever occurs, must be very inefficient.
Nevertheless, there is clearly primate-to-primate transmission among non-human primates in the wild. Transmission between primates is believed to occur by means of saliva since Simian Foamy Virus can be isolated easily from the saliva of infected non-human primates. Transmission by bites theoretically could be one mechanism of transmission from captive, non-human primates to their handlers.
In support of this theory, a gorilla strain of Simian Foamy Virus was detected in two Cameroonian hunters who had had multiple bite injuries during separate fights with gorillas. As we evaluate additional human cases, particularly those occurring in areas where careful observation is possible, we may have to revisit the issues of human-to-human transmission and the potential infectivity of human saliva if any evidence is found contrary to the concept that human-to-human spread does not occur. Next slide, please.
There are few clinical studies to evaluate the transmission of Simian Foamy Virus by blood transfusion. In one small lookback study, reported by Boneva et al., summarized in this slide, no evidence of transmission of Simian Foamy Virus by human-to-human blood transfusion was found. Although this study may provide a basis for optimism, its small size and the absence of information about viral load in the blood donor preclude any firm conclusions. And, in addition, no ideologic association between Simian Foamy Virus and any human disease has been established so far. Next slide, please.
Our concerns today are twofold. We wish to discuss the possibility that Simian Foamy Virus could be transmitted by blood transfusion, and we wish to discuss the risks suggested by Simian Foamy Virus as a model of cross-species transmission of a retrovirus. We know that two Simian Immunodeficiency Virus strains emerged to form HIV Types I and II. And two strains of another Simian retrovirus, Simian T-Lymphotropic Virus, emerged to form HTLV times one and two.
Human diseases associated with infections with these emerging retroviruses were not recognized for many years, and in the case of HTLV I this delay was due in part to the fact that fewer than five percent of persons infected with the virus develop a disease. Even though no human disease has been linked to Simian Foamy Virus infection, these theoretical concerns I've just described may leave many people to urge taking precautionary measures. However, such precautionary regulatory measures require careful consideration of risk level and of the impact on the availability of needed blood products.
Handlers of non-human primates in the laboratory setting are not the only people with close contact with non-human primates. Other groups include zoo workers, people who have non-human primates as pets ‑‑ there are about 15,000 households with such pets in the United States ‑‑ and bench laboratory scientists and technicians who conduct testing of primate serum and tissues. Any of these people could be at various levels of risk for acquiring Simian Foamy Virus infection. The risk for scientists conducting behavioral studies on non-human primates theoretically could be lower than that for scientists conducting other types of studies. It would be a challenge to define precisely which individuals would pose a risk as blood donors.
And now I'd like to show the questions we have for the Committee. Next slide, please. The first question: "In the absence of any known disease association, should FDA be concerned about the potential for transfusion transmission of Simian Foamy Virus?" Next slide.
The second question is, "Do the recent evidence of Simian Foamy Virus infections in humans and the evidence of transmissibility of Simian Foamy Virus by blood in animal studies heighten concern that known and unknown pathogenic viruses of non-human primates could enter the human blood supply?" Next slide.
And the third question, "Do the available scientific data warrant possible consideration of donor exclusion criteria for exposure to non-human primates?" And we would like the Committee to please discuss the factors that we should consider if you recommend this.
Thank you. I'll now take any questions and after that we'll move on to the other presentations. Are there any questions? Dr. Lew.
DR. LEW: Can you just remind me, did you tell us if it causes any disease in the monkeys?
DR. TABOR: I believe it does not, but the next speaker is a sufficient expert that I'll defer to him. And with that, I'll introduce Dr. Walid Heneine from the Centers for Disease Control and Prevention.
DR. NELSON: I was a visitor on one of the other FDA committees a few years ago, namely the ‑‑ I forgot the name of the committee but it dealt with transplanted organs and tissues. And my recollection of that meeting is that currently tissues from non-human primates are not acceptable or permitted by FDA to be transplanted into humans. Is that correct or am I wrong on that?
DR. TABOR: I'd like to defer that question to Dr. Epstein, if I may.
DR. EPSTEIN: The FDA doesn't regulate organ transplantation.
DR. NELSON: Oh. Well, somehow that committee was discussing it and it was an FDA committee. Maybe I was in the wrong room.
DR. NELSON: Xenotransplants.
DR. EPSTEIN: Oh, xenotransplants. Oh, okay. Sorry. Well, there was a moratorium on xenotransplantation from non-human primates on account of various viruses and primates. But I believe the moratorium is now lifted, and I can't comment on the current status.
DR. HOLLINGER: This may be discussed later and if it is, Ed, just let me know. When we talk about donors who have been infected from like '81 to 2000, this is a Boneva study, what do we mean by infected from ‑‑ were there bloods available then in which they found nucleic acid and so on?
DR. TABOR: Well, let me first ask, is Dr. Boneva in the audience by any chance? No. Okay. I've read the paper and I can describe it to you, but perhaps I can ask Dr. Heneine to answer that one too since he's from CDC. The question was how the blood donor samples were collected after the donor was identified in the Dr. Boneva study.
DR. HENEINE: I'll get to it probably in my talk, but let me follow up on the answer of Dr. Epstein regarding the xenotransplantation guidelines. I think the moratorium on using non-human primates as sources of tissues and organs is still in place, and the only species now we think is useful is pigs as sources of xenographs because of the issues of xenogeneic infections and xenogeneic viruses.
DR. EPSTEIN: I just wanted to clarify, I thought what Dr. Nelson was asking was whether there's a policy to exclude human organ donation from humans exposed to primates, and that would not be something that's FDA regulated.
ACTING CHAIRMAN ALLEN: We will have a chance for discussion later, so what I would suggest is that we get through our presentations, asking questions just of the presenters just for clarification, and then we'll get into the broader discussion later. And I suspect most of the ‑‑ or all of the presenters will still be here and can answer at any time. Dr. Heneine?
DR. HENEINE: Thank you again for giving me the opportunity to present our data. I begin with the first slide. I'll be giving a summary of our data thus far. How can I move the ‑‑ move it for me. Next slide, please.
But I'd like to reiterate the fact about our experiences or the lessons we've learned from pathogenic retroviruses we're aware of that have resulted from cross-species transmission. And of course like you've heard from Dr. Tabor, HIV-1, HIV-2 are primary examples that originated from transmission of Simian Immunodeficiency Viruses from chimpanzees and sutimangabees, respectively. But we have also additional examples, human T-Lymphotropic Virus Type 1 or HTLV-1 that resulted from STLV-1; Gibbon Ape Leukemia Virus resulted from a strain of Murine Leukemia Virus and Feline Leukemia Virus that also resulted from transmission from Murine Leukemia Viruses. So these are not dead end zoonotic transmissions, but very successful cross-species infections that have become established and endemic in the new host end-cause disease. So this really highlights the ability of retroviruses to cross species that persist and then spread into the new host and cause disease in many instances. So next.
So what about transmission of Simian retroviruses, what are the mechanisms that could be in fold in this transmission? Or course, hunting non-human primates in the wild, butchering, preparation consumption, keeping non-human primates as pets and of course occupational exposures in zoos and primate centers. Next.
So although we know that HIV-1 and HIV-2 as well as HTLV-1 resulted from these cross-species infections, we still don't know if SIV or other Simian retroviruses continue to cross species to human and what are the public health sequences of these events. We were aware almost ten years ago of isolated cases of transmission of SIV, something our lab has done, and Germans reported a couple of cases of Simian Foamy Virus transmission in occupationally exposed person. And, of course, these reports have raised concerns about the magnitude of these events. So back in 1995 we decided to establish a link study for volunteer testing for simian retroviruses in exposed laboratory workers and primate handlers. Next.
So what today I will do is summarize the data that we have generated from these studies. I will be talking about the prevalence of Simian retroviruses among North American primate handlers, prevalence of the Simian Foamy Viruses in Central Africa, what we have learned from these studies about human-to-human transmissibility and disease and also comment on the risks from other Simian retroviruses, the topic that Dr. Tabor highlighted earlier. Next.
So a little bit of background about those viruses. SIV, we know it's prevalent in African non-human primates, shows a lot of diversity, at least nine different lineages have been described, and the list keeps growing as more studies are done. They're generally benign and natural hosts and only cause disease when they sometimes spread to different hosts. The Simian T-Cell Lymphotropic Viruses, again, they're prevalent in African and Asian primates, there are three different viral species here and can cause disease. Simian Retrovirus Type D or D Type retroviruses are prevalent in Asian Macaques, can cause a pathogenic international host and cause AIDS-like illnesses. And, finally, the Simian Lymphoma viruses, they're ubiquitous in almost all primate species, show species-specific clades and like SIV they appear to be benign in their natural hosts. Next.
So what is the study design on the surveillance in North America that we've been doing? We have a protocol where we invite primate research centers who wish to participate on a voluntary basis in a linked study for testing for these viruses. Participants fill out the questionnaire and provide a serum sample that gets tested serologically first for all those viruses, and we've developed assays that are not commercially available. The active samples are then identified, and those persons are contacted again to provide an additional sample where serology is repeated and DNA is obtained from peripheral blood lymphocytes to do PCR sequence analysis and in many case virus isolation. And we've developed diagnostics to do those tests. And once the individual is found to be infected, the participant will be interviewed closely. Next.
So this is an update of the results we have so far. We have 20 institutions that have joined the study, a total of 3,000 samples collected. Institutions have two choices: To only get tested for SIV or get tested for all four retroviruses. But 441 persons so far have elected to be tested for the four retroviruses. They're from 13 research institutions and four zoos. And here are the results. We saw only two cases were positive for SIV, and these are older cases that we've reported in the past. No STLV infections have been identified. Two cases were seropositive for Simian retroviruses, and I will comment on this later. However, the big surprise was with the prevalence with the Simian Foamy Virus where 15 cases have been identified so far, giving a prevalence of 3.4 percent. One of the SRV-positive cases is also Simian Foamy seropositive. Next.
This gives you an idea about the distribution in research centers versus zoos; again, 3.2 percent in centers versus 4.5 percent. And here are the papers. Just to clarify, the first four cases were published back in 1998, ten additional cases were published or reported earlier this year, and the 15th is a recently identified case from a new institution that enrolled. Next.
Again, we saw similar results from a unlinked survey of zoo workers that was led by Paul Sandstrom and he was with us at CDC where the prevalence of Simian Foamy Virus was found to be about three percent as well in this population versus zero percent rise in workers that had no contact with non-human primates. Next.
Again, as I mentioned, these viruses have cross-speciated with their natural host and therefore follow genetic trees that are similar to the hosts, so, therefore, when we see virus and analyzed it and we can look with which viral species or cluster, you can identify the species origin of these infections. Here, for example, is the ape group, here's the monkey group from baboon, African Queen monkey, macaque and so forth. The samples we were able to evaluate thus far show us that there are eight cases that have chimp-like SIV, four that have baboon-like, one macaque and one African Queen monkey-like. So large variety of different SIV clades that have been identified. And this makes sense because these are the species that are usually commonly used in primate centers and in zoos. Next.
From the interviews, we collect a lot of case histories and histories of exposures, and we also obtain archive samples in these institutions which gives us an idea about the duration of seropositivity in these individuals. In general, all the cases usually report working with the primate species that was responsible for the infection, and many but not all report receiving bites or injuries from that species. The duration of seropositivity, again, shows recent as well as long-standing infections. Next.
So what about the key issues here, about disease and human-to-human transmissibility. Here's some basic background on those cases. Thirteen cases were males and two were females; in fact, they were from the zoos, the females. Seropositivity is a mean of 17 ‑‑ or, no, I think it's 19 years, six to 28 years documented from archive samples. Now, what about disease cessation? Those cases report being in generally good health, but, again, this is ‑‑ I'd like to stop at this point because we receive a lot of questions on this issue. This is a limitation of surveying health persons. We enroll full-time employees that are health, and we identify some of them to be infected, and then we ask them, "How do you feel," and the result is, "We feel fine." So in fact this is not the best design to identify disease cessation. So keep that in mind, that limitation of the study in mind as we discuss the implications of the data.
However, we can tell something about sexual transmission. So six wives of men that reported regular sexual activity, unprotected sexual activity, remain uninfected despite mean documented exposure of 14.5 years, suggesting that probably male-to-female transmission, sexual transmission is not very easy. But, again, we don't have a lot of power in these numbers, and we cannot exclude transmission after longer exposures, similar to the case scenario with HTLV-1 or HTLV-2. We require longer times for sexual transmission.
However, we have a second protocol where we invite infected cases to participate for a long-term follow-up study where we can follow them up clinically and immunologically and virologically for five years, and seven cases have opted to participate in this study. Next.
Of course, the main issue here is transmissibility by donated blood. This is important because we document persistent peripheral blood lymphocyte associated viremia in all cases. We can easily amplify the viral sequences from lymphocytes and also isolate virus from those cases. We're a bit surprised that 11 of the workers we identified were blood donors and six were confirmed to be positive. This is confirmation retrospectively at the time of donation. So if I understood the question earlier about the case from the lookback study which is here, this is a case that was identified retrospectively to have donated blood, and the lookback study here that we worked with with Dr. Boneva really targeted the recipients of that components from this case, in particular two recipients of red cells, one of filter red cells and one of platelets and all tested negative. Again, very little data, not a lot, but we need additional data to have conclusive information. Next.
So the bigger question now is what about transmission in the natural setting? Are these infections only get transmitted to humans in special type of occupational exposures or they also occur in the natural setting? As I mentioned, hunting, butchering and keeping pets is a primary mechanism for this transmission and keeping in fact the estimates about the bush meat trade mainly in Central Africa, central and deforested areas in West Africa. But one to five million tons annually has been estimated to be traded. So there's a lot of contact that occurs in that region. Next.
So we collaborated with Rubin Hopkins to answer the question of prevalence of SFV in samples that were collected from rural villages and persons that reported direct contact with non-human primates. The progress we saw was 0.9 percent. They were all in lowland forests. This is the forested areas where hunting takes place, is prevalent. There were seven men, three women from different villages, and three were PCR-positive. Next.
These are the sites of data collection and these were the areas where the seropositive cases were identified, and the ones in red were those that were also PCR-positive. Again, this area where prevalent practice of hunting and butchering takes place. Next.
Analysis indicated that we have one case infected with a gorilla, one with mandrill and one with a cercopithecus species, more precisely dubrozakeenan. Next.
These are the examples, the pictures of these non-human primates. Next.
And, again, more recent better to confirm our findings from the Pasteur Institute in Paris where the lab reported those in the fourth international Foamy Virus meeting in July in Germany where he screened also southern Cameroonian villagers for Foamy and found 11 out of 720 to be positive, three were PCR-positive and two were hunters, 60 and 67 years old, that have gorilla-type SIV and reported injuries, like you've heard earlier, from gorillas. There was a third person who was a woman that did not ‑‑ has no history of ‑‑ did not report hunting but contact with bush meat. And she has a chimpanzee-type Simian Foamy Virus infection. Next.
So the bigger question right now is what is the scope of these infections? Is it an infection that is only limited to people that have direct contact with primates or are we dealing with a global dissemination of this infection that has gone so far unrecognized? And this is one scenario, how can a global dissemination or emergence of this virus can happen, first, from exposed injured individuals that some of them do get infected but not associated with secondary transmission. However, very few can lead to secondary human-to-human transmission for maybe one or two generations, but then maybe this local epidemic can die out or it can have ‑‑ one of those can really adapt this virus and be able to disseminate and spread among humans. So we really do not know where we are in the scheme of things. Are we here or are we already here? However, only expanded screening would probably tell us where we are. Next.
So how widespread is SIV? Is it ‑‑ first, you can think of it in West Central African countries. What about the situation in Congo, Gabon, Equatorial Guinea, Central Africa public, DRC or Nigeria where all practices of non-human primates hunting and consumption and butchering takes place? Do we have a situation where endemicity has already occurred, and this is sustained by human-to-human spread? We are very interested in looking at this scenario.
We started in fact looking at samples that are collected from different groups, different populations. This is unpublished data that we have recently generated by looking at recently collected Cameroonian blood donors from Yaounde, the capital of Cameroon. We have screened 180 samples and one found SIV-positive individual, giving a prevalence of 0.5 percent. The virus has a mandrill-type SIV, which is consistent with the common hunting of mandrills in Cameroon. More interestingly is that this blood donor was also HIV-1 infected, so we are now dealing with a co-infection situation with HIV-1.
The second population of samples which were already available to us at CDC was a collection of samples from sex workers from the Democratic Republic of Congo, from Kinshasa. Those were collected back in 1985 and we screened those, and one was positive, giving a prevalence of 0.72 percent. Again, the sex workers was also HIV-1 co-infected. Next.
Now, back to this part of the world, again, how widespread SIV is here? Is it only in population exposed to primates or it already has spread out? We do not know. We know cases have been identified in Canada and the U.S. We know in Europe, at least Germany, we have cases identified. We don't know the rest of the other countries. And there's no reason why primate and zoo workers in those countries should not also show evidence of infection. So, again, we need expanded surveillance to answer the question of whether this virus has already spread outside populations exposed to primates. Next.
So I'd like to end up with a summary and conclusions. We've identified substantial SIV infection in U.S., Canadian and Cameroon persons exposed to non-human primates ‑‑ you'll probably hear more from the Canadian speaker later about the Canadian data ‑‑ demonstrated infection with multiple SIV clades, at least seven so far, in both men and women; demonstrated old and recently acquired SIV, at least we can date back 28 or three decades where those infections have been occurring.
So all together it implies that Simian retroviruses are actively crossing into human populations. We used to think that probably HIV-1 or HIV-2 the estimates were probably 70 to 60 or 50 to 70 has crossed into human population and caused the pandemic and that active transmission has stopped since then. Probably those data are a reminder that active transmission has not stopped; it is still ongoing. However, we need to better define disease and spread of Simian Foamy among humans. We have little data on that. Next.
The issue of disease, very important. We think our data can suggest that it is largely still undefined, especially if you consider that you might have disease like in HTLV-1, low incidence, five percent less, after long incubation periods. So we cannot exclude at this point from the available data the incidence of disease. There's many issues that may surround the question of disease. Disease cannot be clade-dependent, like we have seen with HIV. Only two lineages cause disease in humans: The chimpanzee and the sutamangabees, and there's at least seven other lineages that so far appear to be non-transmissible and non-pathogenic to humans. So is this going to be the case for Foamy? We do not know. Definitely opportunities for human-to-human spread will lead to evolution of pathogenicity, and this is something we've documented that we've learned from other virus systems such as SIV.
The recent data on co-infection with HIV in the two cases we've identified are a little bit surprising to us because it begs the question on the impact of co-infection of HIV on disease incidence for SIV as well as for HIV and, again, the issue of increased transmissibility, human transmissibility of SIV. The fact that one of those cases was a blood donor and one is the sex workers of course has implications for blood-borne transmissibility and sexual transmissibility.
But we're becoming increasingly ‑‑ because of the reasons I mentioned, we've become increasingly convinced that we probably need different study designs to identify disease cessation, not from surveying healthy people but probably identify endemic populations and then screen different sick populations just to see where we have some disease cessations. But we are following up the infected case to see if we can identify any incident disease. Next.
So the topic again and the question to the Committee that Dr. Tabor highlighted is what about emergence of other viruses, and what do these data tell us about that? In fact, SIV could be a good surrogate market of xenotransmission of other viruses, including Simian retroviruses, such as SIV or Simian-type D or STLV. And in a sense, it's the center for other possibly more pathogenic viruses. You can think of it this way. We have ongoing screening of our Cameroonian samples for SIV and STLV. Next.
But, in fact, we do have data that tell us that other retroviruses are also crossing, and this is what I alluded to before from our domestic surveillance where we identified two cases that are SIV-infected and two other ones that are seropositive for Simian retrovirus infection, and this is a joint study with Dr. Lerker who will be the other speaker where two cases were identified to be serologically positive. This is the Western Blot here, utilization antibody-positive but virus isolation-negative and PCR-negative. So no evidence of viremia in them but evidence of seropositivity.
This was observed over a two-year period in one person, suggesting probably an infection in this one. However, Case 1 here is the one that is also Simian Foamy-positive. So, again, it's a reminder that the question of other viruses or other Simian retroviruses that may be also crossing is not a hypothetical. Next.
So I will end up with some questions on the emergence of SIV and its implications for the blood supply. What do we consider are the criteria for a new virus to process for the blood supply? Of course, you can think of the infected donors to be asymptomatic, but the viruses causes persistent viremia, so it can transmit. The virus is able to spread among humans and of course can cause ‑‑ has the potential to cause some disease. For SIV, I think the available data show that this is true, this is true, because you have at least PBL associated viremia. This is still unclear at this point, and this is still unclear at this point. But at least some criteria have been met so far.
And my last slide is a big thank you to the people that have been contributing to this work. Many names have already in or out because many have gone to other places, but a large number of people have contributed to it. A special thanks to Bill Switzer, who's the PI of the domestic surveillance, and Nicholas Lab for the Simian Type D serology, our collaborators from Johns Hopkins and Cameroon for the Cameroonian studies. Thank you.
ACTING CHAIRMAN ALLEN: Thank you very much. That was a very good overview. Comments or questions for Dr. Hemeine? Dr. Strong?
DR. STRONG: Within a given species, since you have substantial sequence data, do you see this virus being more or less mutagenic as compared to other viruses?
DR. HENEINE: The virus causes cytopathic effect in-vitro, so it's not an oncogenic virus like HTLV, STLV and others, so it's a cytopathic in-vitro, it causes cell death. In-vivo, in the natural host, it seems to ‑‑ the host seems to control it well and we don't know of any disease that is associated with it. If I think I understood your question is do we see any evidence of adaptive events or mutations after cross-species? We're very interested in this, and actually we've been screening sequences we have already; this is ongoing work. We don't have any data at this point.
DR. KHAN: If I can just comment on that question. In my lab, we have looked at various naturally occurring viruses from Rhesus macaque and from pigtail macaques, and we have analyzed the sequences as well as studied the biological properties of the viruses in-vitro, and we have found that within any one group ‑‑ within any one species there is a diversity in terms of the sequences as well as in terms of the biological properties in-vitro, namely replication properties. So we have not found any two viruses that are identical.
ACTING CHAIRMAN ALLEN: Would you identify yourself to the reporter, please?
DR. KHAN: I'm sorry. Arifa Khan from Sieber.
ACTING CHAIRMAN ALLEN: And do the immune responses cross-react with those differences? In other words, do the antibodies that are formed in the animals also recognize the same?
DR. KHAN: In general, the antibodies against the highly conserved proteins are cross-reactive and can pick up the various different viruses.
ACTING CHAIRMAN ALLEN: Dr. Lew?
DR. LEW: There was a question earlier about viral load. I noticed in your slides you did have a PCR, it looked like, for the Simian Foamy Virus. And so you had the group of husbands and wives. Did anyone try to look at viral load in those husbands and look at viral load over time? Do you have any sense of what the viral load is?
DR. HENEINE: We know it's a cell-associated infection predominantly, so most of the viruses in the peripheral blood lymphocytes, again like HTVL or other HIV. We only analyzed samples from four or five cases where we looked at cell-free viremia by RTPCR and we were ‑‑ all the samples were negative except one time from one case, the seropositive for both type D and Foamy.
Regarding your question on the pro-viral loads, we're beginning to look at that, and we have data from the chimp-infected SIV where we're trying to compare the pro-virus load in naturally infected chimpanzees to the human cases. So far they look similar. We don't have big differences. And they're detectable easily from the peripheral. So if you think of comparing to what we know from HTLV, HIV and Foamy, HTLV has the higher pro-viral loads, Foamy is next and then HIV, and the asymptomatic stage is lowered. So that's the trend we're seeing thus far.
ACTING CHAIRMAN ALLEN: Just picking up on that question, do you have any evidence in the humans that you know are infected, any variability over time in terms of viral load?
DR. HENEINE: The long-term follow-up study where we enrolled those seven cases is going to provide us that information. And we're collecting samples over six months to 12 months, so we'll be able to answer that. I think at this point we don't have any information.
ACTING CHAIRMAN ALLEN: I suspect you don't have any known infected humans that have died that gives you an opportunity for looking at other tissues for evidence of pathology or infection. I'm thinking in particular if you've got peripheral blood lymphocytes, are there other ‑‑ you know, what's happening in lymph nodes, in the spleen and so on? What about some of the non-human primates that are infected, what does pathology show there?
DR. HENEINE: Probably I should have put one slide from the long-term follow up where we looked at distribution. It's not a lot of cases but we were able to amplify viral sequences from semen, from cell palates from saliva and from cell palates from urine. So it looks like ‑‑ of course in addition to peripheral blood lymphocytes. So it does look like there's a wide distribution in the biological fluids of virus-infected cells.
And in some instances, we were able to isolate virus from the throat swabs or cells from saliva. Virus titers, we don't have idea about it, but it does seem at least that the scenario is similar maybe to the natural host in terms of tissue distribution. But, again, very preliminary data on very few cases.
ACTING CHAIRMAN ALLEN: Dr. Lew again and then Dr. Klein.
DR. LEW: Yes. And you mentioned cytopathic effects. Which cell lines are affected and what type of cytopathic effects are you seeing?
DR. HENEINE: The Foamy Virus are notorious to have a wide cytotropism, wide host cytotropism, and they're cytopathic to many different cell types. We routinely grow them in human cell lines, IG cells, whatever, canine cell lines, dark cell lines, I mean they grow very easily in different cell lines from different primates ‑‑ very disparate primate species.
DR. KLEIN: Do you have any indication of the percentage of circulating lymphocytes infected in the animals and any quantification of the nodes or other lymphoid tissues?
DR. HENEINE: No, we don't, but based on the pro-viral load data, the limited data that we have, we did some comparison with our experience with HTLV and asymptomatic HIV-1. It does seem it's in between. HTLV-1 is really at the higher end, Foamy is in between, and there was no differences between primates and humans.
DR. KLEIN: Is there any evidence on what happens to a newly infected animal in terms of spread of the virus?
DR. HENEINE: Well, maybe some data from the next speakers will tell us about the newly infected animals.
ACTING CHAIRMAN ALLEN: Please identify yourself.
DR. SANDSTROM: Paul Sandstrom from the Public Health Agency of Canada. Dr. Brooks in his presentation that's going to be after Arifa's will present some data on viral load or at least quantitative data on viral load in comparison to cells as well as some indication of what goes on in the animals in the weeks after infection.
ACTING CHAIRMAN ALLEN: Dr. Hollinger?
DR. HOLLINGER: Just want to be clear about something. You find this only in the PBLs and not in the plasma at all; is that correct?
DR. HENEINE: Yes.
DR. HOLLINGER: Okay. The second this is you showed a slide which showed species specificity and the origin of some of these Simian viruses, the SFV. Do you find transmissibility then between gorillas and mandrills? I mean some of the studies have shown this to be transmitted apparently to humans, but I would think that you'd also see it transmitted to other non-human primates as well. Has that been shown?
DR. HENEINE: Yes. It's primarily species ‑‑ the clades and their primate species have co-evolved over time and this is wide evidence. In fact, we could use Foamy Virus as the best model for host virus co-evolution in cross-speciation, the best model we have so far. However, there is also cross-species infections, and we think we've identified at least a couple of animals that have dual infections with their own clade and another clade. These came actually from captive animals that were in contact with other primate species. So primarily you see species-specific variance, but we also saw, though infrequently, cross-species infections among primates.
ACTING CHAIRMAN ALLEN: Dr. Cunningham, Ron Wilson and Dr. Epstein.
DR. CUNNINGHAM: I don't know if I missed this or not but when you have had a chance to look at samples over a period of time, is the genome stable or does it seem to have mutational alterations over some period of time?
DR. HENEINE: That's a good question. I think the genome of Foamy compared to HIV is more stable. We still don't have quantitative data when you compare it to, say, HTLV, which is very stable. But at this point we think it's more at the stable end rather than the high diversity end variable like HIV is. But you could see evidence of quasi-species in the infected animal and in humans, and you could see some evolution over time, but it is slow compared to HIV.
MR. WILSON: Thank you, Walid. In the Boneva study, do you happen to know what the duration of storage of the blood components was before transfusion?
DR. HENEINE: I'm sorry, I didn't hear you, in what?
MR. WILSON: Yes. In the Boneva study?
DR. HENEINE: Yes.
MR. WILSON: Do we know how long the units were stored by the refrigerator at room temperature before transfusion? Because in the HTLV experience, we know that if units are stored more than two weeks, the rate of transmission falls off, presumably related to death of leukocytes. And I just wonder whether a similar phenomenon has gone on and whether we learned anything in that regard from the lookback study or, conversely, has it ever been examined in-vitro what is the storage stability at four degrees or room temperature of infected leukocytes?
DR. HENEINE: I don't recall the data if it's in the paper, but we can check the paper and get back to the question of duration.
MR. WILSON: I think it's in Table 1.
DR. HENEINE: Stability in-vitro, we have not looked at it.
ACTING CHAIRMAN ALLEN: Dr. Strong.
DR. STRONG: SFV has also been considered to be an ideal gene vector for those that are doing molecular genetic engineering. Do you know to what extent it has penetrated that marketplace?
DR. HENEINE: Well, most of the vectors are actually non-replicating vectors, which is a good thing. There's also interest with some groups, including Dr. Folks in our branch, to use live vectors for gene delivery. It all depends on the incidence of disease and what these infections do. There is a lot of questions raised right now in the field as we're understanding that those infections are probably more prevalent than we previously thought than whether or not ‑‑ I guess it all depends on how the data come out. But the vectors have large number of advantages.
DR. STRONG: Thank you.
ACTING CHAIRMAN ALLEN: Other burning questions? If not, I think let's move on to our presentations and come back for the general discussion. Our next speaker is Dr. Kahn of Simian Foamy Virus transmission studies.
DR. KHAN: Thank you. Next slide, please. As you have heard, SFV can be transmitted to humans by injuries involving infected non-human primates, most probably due to the saliva, as in the case of some animal handlers and zoo keepers. Additionally, recent data has shown that hunters in Africa can be infected due to exposure to blood tissues and meat consumption infected among human primates.
In all of these cases, the infection results in long-term persistence in the host, and in the next slide is indicated the reason why. Because the viral sequences in a retrovirus must integrate as a normal part of the host cell DNA as a critical part of the retrovirus life cycle. This results in lifelong infection of the host cell.
In the next slide, in general, in case of other retroviruses it's been demonstrated that retrovirus integration can in many cases result in the generation of pathogenic viruses or the virus insertion directly can result in mutagenesis by various mechanisms, such as activation of tumor genes or disruption of normal gene functions, such as tumor suppressor genes. Next slide, please.
Although to date there has not bee any clear evidence that Simian Foamy Virus is associated with pathogenesis; however, this retrovirus is unique in its biological properties and therefore there are concerns regarding Simian Foamy Virus.
Number one, primarily it's the unrestricted host ranges of Simian Foamy Viruses. Regardless of the species of origin, most Simian Foamy Viruses have demonstrated a very broad host range. They can infect avian cells as well as a variety of mammalian cells, including human, as you have heard. They have a very broad tissue tropism as well as a very broad cell tropism, and the question came up earlier regarding how does the virus replicate or cause CPE in different cell types. My lab has done studies in a variety of different human cell lines, and we have found that the virus replicates highly efficiently in fibroblasts and then the replication varies depending upon the different cell types. In general, in epithelial cells, we found that the replication rate lags that of fibroblasts and in lymphoid cells the rate is also different. So the virus can infect all cell types of various species, however the replication of a particular virus is dependent upon the cell that it infects.
Additionally, there was a question earlier regarding the different types ‑‑ or Foamy viruses of a certain species, and I wanted to just mention that, again, from one particular species in our experiences in macaques, we find that you can get viruses with different replication properties. They range from highly efficient to less efficient; however, in all cases we do get infection of the cells.
As I mentioned, we do see cytopathicity to various extents depending upon the cell type. Foamy Virus, in all cases you get infection that can result in latency, especially in humans, as you have heard. In one case, infectious virus was isolated 30 years post-infection from an infected human, and this was a CDC study. And it is this latency that is of concern in terms of its potential transmission in blood, because the virus can persist in a quiescent state and basically it can even go undetected, maybe asymptomatic. However, because it is a retrovirus it has the opportunity to generate into a pathogenic virus and then therefore result in serious consequences.
It is this concern of its persistence in human cells, especially PBMCs, that is the question that we are addressing today, whether there is a potential risk in terms of blood transfusion. The next slide, please.
And this just states the question, and this question was also posed to the Committee in December 2001. The next slide. At that time, data was lacking in terms of blood transmission studies and this was the FDA study that I had proposed. Basically, we proposed that we would take whole blood from an SFV-infected Rhesus macaque and inject it into negative animals. The blood recipients will be monitored for SFV infection by a variety of parameters ‑‑ virological, serological, molecular as well as clinical analysis. And we will follow the inoculated animals or the transfused animals for at least one year to evaluate the infection by blood transfusion.
And in the next slide is outlined the blood transfusion study that we have now conducted in Rhesus macaque. We use a well characterized donor in which the Simian Foamy Virus has been isolated, the sequences determined in a limited extent, as well as the biological properties studied. And the recipient animals are retrovirus-negative. They were obtained from an FDA colony that's at Morgan Island, South Carolina, and the recipients were negative for other retroviruses, including SRV, SIV, STLV and of course for Simian Foamy Virus.
The animals were initially screened by antibody assays. At that point, while we were waiting for the results, they were housed individually. Prior to the actual initiation of the study, the negativity of the animals was confirmed by PCR and then further additionally confirmed by virus isolation, because we wanted to be absolutely sure that there was not any low-level infection in the animals that could eventually come up and confuse the results of our blood transfusion study. So we had confirmed negative animals for the study, and we additionally included a negative animal as a control in the study. And the study was done under approved animal protocol, of course, and the donor and the recipients were housed in different rooms and each was housed singly, of course.
And the next slide is the protocol that we followed. Blood was collected prior to transfusion to prepare controlled or pre-bleed samples or transfused samples for PBMC and plasma. And, additionally, the animals were tested by serum chemistry and hematology to evaluate their clinical status at the initiation of the study.
For blood transfer, 20 mls of whole blood was drawn in Heparin from a donor animal, and 10 mls was injected into each of the recipients. And I should mention that we went with using Heparin as the anticoagulant because in SIV studies we know that blood collected in Heparin can transmit SIV into other naive animals ‑‑ monkeys ‑‑ and therefore we wanted to use a model that we know works for a retrovirus to initially evaluate the results. And the control monkey received 10 mls of just PBS.
In the next slide it's indicated how we monitored the animals for virus infection. We did antibody detection by initially Dot Blot and confirmation by Western Blot. Virus sequences were detected by PCR and nucleotide sequences determined for confirmation of identity. Virus isolation was done by using monkey PBMCs in cold-culture studies I will describe later, as well as the animals were monitored clinically by hematology and serum chemistry as well as by physical exam.
And I will not be able to present all of the data here, but I should indicate that initially during abut the first three months of this study the animals were very closely monitored initially on a weekly basis. All of these assays were conducted on samples, conducted weekly, and once we could see when the animal developed a positive result, then it was less frequently.
In the next slide indicated Western Blot data of monkey plasma in which the experiment was done to detect any antibodies that were present in monkey plasma by incubating them with strips of nitrocellulose that contained Foamy Virus antigen from infected cell lysate. Number 1 in each case indicates the day of the blood transfer, and Number 2 indicates 48 months post-transfusion. This is the profile that is seen for the donor animal. These bands are specific for Foamy Virus infection because they're antibody-specific bands for Foamy.
In the case of one of the recipients, Recipient 1, this is the sample from the day of blood transfusion, and this is 48 months post-transfusion, and you can see Foamy-specific antibodies that have already developed ‑‑ that actually developed much earlier and you can see persistence of these antibodies at 48 months post-transfusion. Similarly, in the second recipient animal, we also can see Foamy-specific antibodies developed and persisting for 48 months.
In the negative control animal, you can see that there are background bands that were present on the day of blood transfusion as well as the same level persisting even at 48 months post-transfusion. There was no difference in terms of increased levels, and I should mention when these are lined up side by side none of these bands correspond to any of the bands here. Even these two bands are in between the two virus-specific bands.
In the next slide, I'll describe to you the studies that we conducted to demonstrate that infectious virus can be isolated from the blood-transfused animals. Monkey PBMCs were cold-cultured with a highly susceptible cell line that we had found in our lab ‑‑ Mus dunni cells. We have found several years ago that Mus dunni cells, which is a wild mouse cell line, is a fibroblast cell line, was highly sensitive to Foamy virus detection, so we used that in our lab.
And the control was Mus dunni without PBMCs, and this was set up as a negative control that is critical for the reverse transcriptor assay that is used to determine virus production in the assay. And then filtered supernatant was collected at each cell passage every three to four days for testing of the reverse transcriptor assay for virus production. And if a culture was negative, we would continue the culturing for up to 30 days. Otherwise, if there was cytopathic effects seen, then we would terminate the culture when the culture had greater than 75 percent cell destruction.
The PBMC samples that were analyzed in the assay were from the transfused monkeys, both of the recipients, R-1 and R-2. We also used the donor monkey to demonstrate virus isolation from the day of blood transfer, and the negative control monkey was used as a control sample.
In the next slide are shown the results from the virus isolation study. Basically, these are the days in culture and up here is the RT activity, which indicates the amount of ‑‑ which correlates with the amount of virus that's released into the medium. So the Mus dunni cells without any PBMCs are shown in the blue triangle in all of the four panels, and this is the background activity. From the donor animal, we found that the virus was detected after ten days of cold culture. And, as you can see, it increased ‑‑ virus production increased rapidly once CPE started, and then the culture was terminated about day 18 here. And this is high virus production with high CPE here.
In the negative control animal, which is in the diamond red here, these are cells obtained from the animal at 22 weeks post-blood transfusion. Of course this animal did not receive any blood, but this is the time point that we used for the blood transfusion animals. And here at this time point the PBMCs from the negative control animal did not release any virus and the animal was clean.
From both the recipient animals, R-1 and R-2, virus could be isolated from the PBMCs of the 22-week sample in both cases. However, there was no virus released from the day of blood transfer that is shown here in the squares in both cases, and that ran along the same levels as the negative Mus dunni cell control.
The next slide, these results that I've presented to you indicate that Simian Foamy Virus was transmitted by whole blood transfusion and established a persistent virus infection in naive monkeys. This was demonstrated by the detection of virus-specific antibodies, by nucleotide sequence analysis as well as by virus isolation. I should mention to you that the nucleotide sequence analysis that we did was for a limited region in a part of the viral genome, and in that region the sequences that were present in the transfused animals was identical to that in the donor animal.
And I also wanted to mention that in this study we used one donor, and we had infection in both of the recipients. In another study that is still in progress, we used a different donor whose Foamy Virus has distinct biological properties from this particular donor virus. And in that case, as of right now, we do not have evidence of blood transfer of the virus. So this sort of I think emphasizes the fact that the transmission can occur but it might be affected by other factors including the virus properties itself or other properties of the host.
In the next slide, this is my acknowledgement slide. I just want to acknowledge Tanya Kramar, who has done a tremendous effort in generating the data for the study, as well as the wonderful Sieber Veterinary staff and also to thank Jay Epstein and Ed Tabor and Yura Nakase for their consultation during the studies. Thank you.
ACTING CHAIRMAN ALLEN: Thank you, Dr. Khan. Dr. Strong?
DR. STRONG: Did you also monitor clinical symptomology? Are there any symptoms, blood chemistries, et cetera?
DR. KHAN: Yes. I'm sorry I didn't mention that. Basically, in terms of ‑‑ there is no overt symptomology in the animals. They were examined regularly by physical exam and fever and all of the physical parameters. In terms of the clinical reports, I have not yet completely analyzed all of them, but as of right now there does not seem to be anything that sticks out as something being abnormal. But I do have all of the results longitudinally for the entire year, so we will look at each of the parameters on the long list of different values and then see if we see anything developing over time. But there's nothing overt that we can see.
DR. STRONG: I think it was on one of your slides you found the virus in neural tissue. Can you say something about that?
DR. KHAN: That was from published data in terms of the neural cells. There's a report by Ruccio et al. in which they have shown that a variety of different cells and tissue culture, including the neural cells, can be infected with the virus. But also, actually, virus has been isolated from the brain of monkeys, so in 91 primates it seems that the virus is distributed throughout the entire animal in terms of the viral DNA sequences. Now, in terms of the actual expression of infectious virus, that seems more limited.
ACTING CHAIRMAN ALLEN: Other questions? When it takes so long to do such a study, it obviously is not a very happy question to ask but are you now going to go back and look at individual components, i.e. peripheral blood monocytes separated and washed, packed red cells and washed packed red cells and plasma?
DR. KHAN: Actually, the way I'm thinking about addressing that ‑‑ of course it's a scientific curiosity as well as a public health question. What we are setting up to do is we will be evaluating these cells over time that we have collected from the animals. We have frozen down and preserved PBMCs and we will see which cells are infected at what time post-transfusion so we can get a handle what population of cells are infected or are they all infected? And we will be conducting some additional studies in which we can get fresh samples and we can see which component might be infected in fresh samples.
In terms of ‑‑ I think once we have an answer as to what cell types are infected, then I think we can see whether we need to do any more transfer studies.
MR. NAKASE: Arifa, thank you very much for a nice talk. This is Yura Nakase, FDA. You said what's the timeline for developing the antibodies and, as you said, that takes by week 20 you see the virus coming out, at least in the cell culture. When do you see the antibodies developing and if they are ‑‑ and I read in the literature there are neutralizing antibodies that can suppress the virus ‑‑ what's the timing in these animal experiments when you see antibodies and when you see the virus?
DR. KHAN: Right. We have that data and I did not sort of include all of those tables. In terms of the neutralizing antibodies, we're currently looking at the presence of neutralizing antibodies and the titers in these animals and in the parent animal. So far we don't have data on development of neutralizing antibodies with time, but we just have data with developing whole antibodies in Dot Blot assay. I'm struggling to recall the table. I think the PCR result is earlier than antibody development, and I will have to go back and check it.
ACTING CHAIRMAN ALLEN: Other questions or comments? Yes, Dr. Lew?
DR. LEW: Just to look at the issue for while I'm wondering if it's pathogenic, are there any studies that are going to aggressively look for this, like in immunocompromised animals, although just the thought of seeing the slide on the HIV with the Foamy Virus it's quite possible that having them together would make HIV less pathogenic. I mean who knows, but I mean ‑‑
DR. KHAN: It can go either way, you're absolutely right. And I think those are studies that need to be done formally. I think there is heresy but I don't think it's been done rigorously. Actually, we have samples in the lab which we have obtained from other projects that I've been doing in my lab related to SIV and AIDS in monkeys, and we have some animals that were Foamy-negative and some that are positive, so we can go back and look at that question now to see what is the relationship of the two viruses in terms of expression over time ‑‑ or replication, I should say.
DR. SANDSTROM: Paul Sandstrom, Public Health Agency of Canada. Just on the issue around HIV or lenti viruses and Foamy Virus, there is a recent publication that came out in Journal Virology, I think it was, what, two weeks ago, that showed that ‑‑ it was an in-vitro system so it was done in cell culture, but that the presence of persistent infection by SFV increased the ‑‑ it wasn't infectivity but it was actually the binding of lenti viruses to cells. It was probably through Heparin celfate profile proteoglycin pathways but implying that there might have some effect ‑‑ that Foamy Virus infection might have some effect on, I guess, the ability of envelope viruses to infect cells.
DR. KHAN: I mean I think it's fortunate that the two viruses are fairly different genetically, because in cases where the viruses are related, of course there's recombination and that would be an additional concern. So I think these are situations that need to be further studied in the co-infection. Nick?
MR. LERKER: Nick Lerker from UC Davis. Just a comment on an observation we've made on that last question. In the SIV macaque model for AIDS, we have the so-called fast progressors. There's different courses of infection in these animals. And one of the questions we wanted to know is could it be possible that Foamy Virus might be associated ‑‑ or co-infection with Foamy Virus associated with these fast-progressing cases. So we retrospectively looked at fast progressors and non-fast progressors for their Foamy Virus status, and in the retrospective study we did not find any significant difference in terms of their SIV clinical course related to the Foamy Virus status. So it did not seem to be a co-factor in the common sense of that.
DR. KHAN: So, Nick, may I just ask you, did you look at the levels of virus replication in the study or how did you ‑‑
MR. LERKER: This was a rather crude retrospective study just looking at ‑‑ it was animals that had been identified as fast progressors.
DR. KHAN: Oh, okay.
MR. LERKER: We then went back and looked at their stored archive serum for Foamy Virus status, and so we did not look at virus loads. That would be need to be done as well.
ACTING CHAIRMAN ALLEN: Thank you. Other questions for Dr. Kahn? Okay. We'll move on. Our next two presentations are from colleagues at Health Canada, recent research results, Dr. James Brooks. Welcome.
DR. BROOKS: So I'd like to thank people on the Blood Products Advisory Committee for inviting me to present to you the data I will today. I'm James Brooks, and I work at the National HIV and Retrovirology Laboratories, which is actually ‑‑ now there's been a new agency created, so now we're actually part of the Public Health Agency of Canada.
And under my other hat, I'm a clinician, I'm an infectious disease doctor, and so I'm also under the auspices of the University of Ottawa in the Division of Infectious Diseases. So I'm here today, and I'm going to talk to you about Simian Foamy Virus transmission through blood transfusion. Next slide, please.
It's been well covered before but I'm just going to briefly go over Simian Foamy Virus infection in humans just to highlight a couple of points just from my perspective, but I certainly won't go over things exhaustively, as it's been well covered by my colleagues. And I'll talk a little bit about the Canadian expanse with Simian Foamy Virus because I think it's pertinent for two reasons: One is the demographics of the exposure of people who work with non-human primates, and also to highlight some of the unique factors about Foamy Virus infection that we think are relevant. And then I'll go on to talk about the results of our blood transfusion study. Next slide, please.
So as has been described before, that all the human retroviruses that are known to have originated from non-human primates, there's ongoing transmission with other Simian retroviruses, such as SFV, SIV and SRV. We think that SFV is important because it's probably the most easily transmitted of the Simian retroviruses. And the second point is we have good assays to follow this. But our perspective is that this is just a marker of sites where retroviral transmission can occur. Next slide, please.
As has been described previously so well by Walid, these are the S Foamy Virus infections in humans or publications describing Foamy Virus infections in humans that have been published. And this is both in the occupational setting and most recently with the paper by Nathan Wolfe. I just want to point out here that one of the papers that we put out on cross-species retroviral transmission from macaques to humans was important because the most popular animal that is used by medical research is either a cynomolgus or the rhesus macaque and we've shown that there was an infection that did originate out of macaques and was transmitted to humans. Next slide, please.
I'll talk a little bit about what the climate is of exposure to non-human primates in the occupational setting, at least in our experience. Next slide, please.
This graph represents the monkeys or non-human primates in general who are registered with the Canadian Council on Animal Care, which is an organization that facilitates accreditation for people involved in non-human primate research. And as you can see, as I have more recent data that's not in this slide, that there's around 2,000 non-human primates a year that are registered in Canada for experimental purposes. And the thing to bear in mind is that each one of these animals is going to be looked after by a number of people, including people who clean the cages out, the people that mobilize them for experiments, the veterinarians who are involved and also the laboratory workers who are going to be involved in analyzing the samples. And as you can see, it was mentioned that most of these animals are either cynomolgus or rhesus macaques. Next slide, please.
When you try and identify the low side where people are exposed to non-human primates, it's difficult information because people are reluctant to divulge that they're involved in work with non-human primates. What I am able to find out is that there are 21 institutions that are registered with the Canadian Council of Animal Care in Canada as being involved in caring for non-human primates. When you look at a larger scale and you look at an industry-sponsored organization that is interested in promoting the welfare the animals in zoos and aquariums, there's another 28 institutions there that are registered, but not all of those would have non-human primates. And if you take the perspective of looking at any institution that's involved in having animals for display purposes in Canada, there's more than 100 institutions in Canada. Next slide, please.
And this is just to show you the relevant data from the United States, and this was kindly provided by Tom Damercus at the Division of Quarantine. As you can see, again the predominant animals that are imported into the United States are both cynomolgus and rhesus macaques, and the numbers again more recent data shows it's somewhere between 10,000 and 15,000. This is just to give you some perspective on the exposure. Next slide, please.
And then this I'm just going to mention this very briefly and what our experience was with human Foamy Virus infection in the occupational setting. And it's important too for the understanding of what the levels were of exposure and again for the macaque infection. Next slide, please.
As you can see, the burden of exposure is very high and you can see that of the people that were in the study more than 90 percent were exposed to some of the fluids. In terms of the intensity of exposure individually, bites were present in about three-quarters of the people who were involved in the study, and things such as needle sticks were still present in about half of the people in the study. Next slide, please.
And what we found was that there were about two out of 46 ‑‑ well, there were exactly two out of 46 participants who were Foamy Virus-positive, and this represented about four percent of the study population, which is consistent with other studies. But, importantly, the infection, at least for the one that we were able to have molecular data on, originated out of a macaque. Next slide.
If we were to ask the question are we able to define the risk based on the pattern of exposure, the answer was, no, the demographics of the infected and uninfected were the same, and if you look at the patterns of exposure between the infected and the uninfected, they were exactly the same. When we looked from the perspective of what potential risk that it exposed the blood supply to, we found that about half of the people had donated blood and the question was phrased, "ever," so it's not necessarily regular blood donors. From the perspective in Canada, the regular blood donation occurs in less than five percent of the population. So this group would be overrepresented, and it's probably due to the part that because of their work in a biomedical institution, there's on-site recruitment for a blood donation. So they would be frequently participating. Next slide, please.
And I won't go through this in detail because again it's been covered by Walid, but this is sort of the segue of where we launched into the study of the blood donation.
I just will highlight one point about -- these are the paraphrasing of the questions that were put out by BPAC at the last meeting, and that is: does foamy virus cause disease in humans?
And really one of the things that I think Walid brought up very well is the selection bias, so that if somebody is unwell or is deceased, they would not be captured by these studies that have been done here in an occupational setting.
And then finally this is where we move forward, and Walid has already discussed the study here by Dr. Boneva and the limited information that is currently available.
Next slide, please.
So the study design was very similar to Arifa's and it's simple in conception in that we took blood from a foamy virus positive donor and transfused it into a negative recipient, and then what we did was did a sham transfusion with saline into a negative monkey and followed the out over time, carefully keeping them in a segregated and foamy free environment so that we could be sure that if we did document evidence of transfusion or -- sorry -- evidence of infection in the negative monkey, it was the result of the transfusion.
Next slide, please.
We did some baseline work, and we were able to establish that the donor and recipient had O type blood. The blood grouping in monkey is quite complicated, but at least at this level we're comfortable that we're compatible.
We also took white cells, lymphocytes out of the donor animal and were able to show in tissue culture that they produced infectious virus. So that there was virus there that would be potentially infectious to the recipient.
And then we also were able to show that if we took the virus from the donor monkey it was able to infect the white cells from the recipient monkey. So there was no a priori reason why the monkey that we had found that was foamy virus negative could not get infected with the foamy virus.
Next slide, please.
This was our protocol in that we quarantined the monkeys at minus 12 weeks, but in fact, we had data going back that they were either foamy virus positive or foamy virus negative, respectively, for about two years before then, but this was when they were sort of enrolled in putting the strict segregation.
And then at time zero -- and the lines here represent sample drawings -- for the transfusion we used ten percent blood volume of the recipient monkey meant to approximate about 500 mLs of blood in a human, and it was citrated blood, and it was a direct transfusion.
And then the other thing he did was he harvested a lymph node at around the 16 week time point.
Next slide, please.
So these are the results that we were able to obtain. This is a Western Blot with a combination of different foamy virus antigens that are present, and it's an assay that's being well described and published by others and us, and so this is the pattern that you would see with the donor monkey with the gag doublet here.
And here is the recipient that you can see at minus 12 weeks and zero, at time zero. It's clearly negative. This is interesting because what you see here is you see a conferring of passive immunity in the immunoglobulins that went across from the donor monkey, and you can see that the pattern here wanes at four weeks, and so they're negative at eight weeks.
And then by nine weeks trust me. It's there. There is a gag doublet here, and I'm happy to show data to anybody who would look, but by 12 weeks you're seeing that gag doublet, and the strong evidence at that point is seroconversion in the recipient monkey, and if you look at the placebo monkey, you can see that they're clean throughout that experiment.
Next slide, please.
When we asked the question can we find evidence of the actual virus using published PCR primers in a nested reaction, the answer is yes, and the time points correspond here. Again, if you look at the donor monkey, you'll see the bend here is characteristics, 464 bases. We have sequenced this particular piece of DNA. So we know it is foamy virus.
And then if you look here again at minus 12 weeks, zero, one, two are negative, and then here at about the eight week mark there, you see that there is a strong signal, again, at nine, 12, it remains the same. If you look at the placebo monkey, they're negative.
The next slide, please.
And I know there's been some questions about this, and this is -- Harriet Mertks and the technician in my lab developed this real time PCR assay, and what we were able to do is to get a pro viral load on DNA extracted from whole blood, and so these are copies per thousand cells, and this is total cells in the DNA extracted from the blood.
And as you can see, this is the donor, has viral load, and it ranges here between five and ten, and this is the placebo. As you can see, it remained at zero throughout the course of the experiment.
The recipient monkey here. This is right at the threshold of detection. So depending on how many replicates you can do, it can pop up at a very, very low level at six weeks here, and then it's a strong signal here at eight weeks, and it goes to quite a high level here to somewhere over 40 copies per thousand cells and then decreases to what we would predict to be the set point here, and this is around four copies per thousand cells.
Next slide, please.
We also did some preliminary immunological analysis in this experiment, and you know, I'm going to say it's preliminary just because the sample size here is one. So it has to be interpreted with caution.
What you see in both the recipient and placebo monkey is there's a decrease in the total lymphocyte count, and when I discussed this with the veterinarian who was involved in the study, he says it's not inconsistent with the animals being housed singly. He said that in terms of the cynomolgus macaque monkeys that were used in the experiment, one of the most stressful things that can happen to them is to be taken out of the group setting.
So he says this is not unexpected, and once we determined that the animal had become foamy virus positive, we would relax the housing requirements, and with the negative placebo monkeys return back to the negative colony, and so you can see that once that pressure was off, then they came back to baseline.
Next slide, please.
If we look at the CD4/CD8 ratio in both the recipient and the placebo, the placebo monkey here is just showing some gradual variation, but really, you know, you could draw a line through there and it looks about the same.
When we looked at the recipient monkey in terms of what happened to this ratio of cells, you can see that this is the time of transfusion here, that something happens, that there's a decrease here in the ratio to .8, and then there's a doubling here, an inversion, as it were, up to 1.6 from the ratio, and then it comes back to around baseline.
So as you can see, this could be either -- because it's a reciprocal relationship, it can either be the CD4 going up or the CD8 going down.
So when we went back and when we just looked at the data more carefully to try and figure out what was going on, the pattern that we're seeing here, and this is in the recipient monkey is that you see that the CD4 count dropped initially after transfusion here, and then by a delay there probably around two weeks, then there was a fall in the CD8 count, and that called an inversion of the ratios, and then over time they both come back to baseline.
Next slide, please.
So from this small study and the preliminary data that we've been able to accumulate, what we feel we've been able to establish is that simian foamy virus is transmissible by whole blood transfusion in the native host.
The second point is that there's an apparent immunologic disturbance after the transfusion. This could be for any number of reasons. It could be related to the transfusion alone. It could be related to foamy virus transmission. It could be related to some other virus that is transmitted, and because it's only one monkey that died, I would urge you to interpret that with caution.
Then there wasn't a good way to present this, but I will tell you because it's related to the new information that there is a replication competent foamy virus present at distal sites, and in this experiment when we took the lymph node, we removed some of the lymphocytes and isolated them and put them in tissue culture and stimulated them, then extracted RNA, treated them with RNAs for DNAs, and then looked to find out whether we could detect evidence of replicating virus with RTPCR, and the answer to the question was, yes, we could at that level.
And next slide, please.
And so this is meant to address some of the obvious questions that will come out of this, plus some caveats, and that is which blood components transmit foamy virus and will there be any inactivation steps that will prevent transmission of the foamy virus.
And then what about people who have captured previously kept monkeys and pets?
So I'll just deal with the first two points and then just give some perspective on the last point.
Next slide, please.
Well, in order to show transmissibility of foamy virus through blood transfusion, we only required two monkeys. So that's it. It's a relatively easy experiment, but to demonstrate non-transmissibility is much more difficult. I'm not a mathematician or an epidemiologist, but from what I've been able to ascertain is that in order to show non-transmissibility at a five percent level, even if you had 30 monkeys, the confidence intervals at that would still be ten percent. So it's difficult to show absolutely there's no transmission.
And this is obviously made more difficult by the context of relatively few foamy virus free monkeys being available.
Next slide, please.
And from the perspective of pet ownership of non-human primates, and this is the only data that I could find that comes from the United States, and there was no Canadian data that I could find. Importation of non-human primates as pets was banned in 1972, but before that, in these two years there were more than 200,000 non-human primates imported as pets.
I'm going to point out here that these are new world primates, okay, and there hasn't been an established -- it hasn't been established that there is a transmission of foamy virus from new world primates into humans, and there are no known serological assays to detect for this infection, but this is just meant to place it into some context.
And the next slide, please.
So these are the people that I'd like to thank, and these are the people that work with me or I work for. There's Harriet Mertks, who does all of the work and did all of these experiments and did a great job on them. She keeps all of the data and keeps me organized.
And Paul Sandstrom who is my boss, who has been very supportive here.
And Frank Buffer who is our boss, very supportive.
But over at the Health Products and Food Branch, there's Jocelin Fornier (phonetic), and he's the veterinarian that's been instrumental in getting this study going.
There's Peter Ganz who has been very supportive from the perspective of the blood regulators.
And Dr. Rouimiana Boneva, who was very helpful in terms of setting up this study in the beginning, and also to the people who support me as a clinician-scientist in the Division of Infectious Diseases in the Department of Medicine, University of Ottawa.
I'm just going to leave you with this slide because I think it's important for a perspective because what it reminds me to tell you is that while we were able to look for foamy virus transmission in areas where it may seem likely, there are other situations where it may be occurring that we have no idea, and it's only a matter of where we shine the light.
So this is Jane Goodal. This is from a national newspaper, but as you can see, in sort of settings, risk prolonged exposure to non-human primates. You might expect transmission to occur there, but this photograph there, and I got this from somebody I know, this is her mother, and this is back probably in the late '40s this photograph was taken, and here I think this is a macaque she's got. So it's unknown how many people would be like this around.
And here what you have is you have a monkey here and a cat who are eating out of the same bowl, and both of these animals are potentially foamy virus infected with respect to the thing, and there has been evidence in the past of transmission of retroviruses between felines and non-human primates. So here you're having this crucible that has been created that we may not be aware of, and this may be unknowable.
Anyway, thank you for your time.
ACTING CHAIRMAN ALLEN: Thank you.
That photograph of Jane Goodal reminds me of a report I saw after the epidemic of monkeypox that we had here in the United States, what a year or two ago, transmitted by prairie dogs or that was the prairie dogs with the vector, and there was more than one picture of humans kissing their prairie dogs with the explanation, "They're so cute." So transmission does occur.
Questions for Dr. Brooks? Dr. Strong.
DR. STRONG: Since you brought that one up, I was very impressed with the high rate of donation amongst people who were infected with SFV. So I wonder if we should be infecting the population to increase our blood donations.
DR. BROOKS: Let me just clarify. Those were people who were involved in the study. So that was total people involved in the study, both infected and uninfected.
Still 50 percent is still ten times better than we do elsewhere.
ACTING CHAIRMAN ALLEN: Dr. Klein.
DR. KLEIN: Of the 2,000 inoculated primates a year that are for medical research in Canada, are a large percentage of those imported or are they bred?
DR. BROOKS: I won't be able to provide you with absolute numbers on this. There are imported ones, but there are also ones that are bred. But the answer is both, and the numbers for the United States that I got from Tom DeMarcus, that's purely imports.
ACTING CHAIRMAN ALLEN: Dr. Tabor.
DR. TABOR: Thanks again for coming down South to present your data. It has been very helpful, and I know between your studies and Dr. Khan's studies, it really places the SFV discussion in a completely different light than if we didn't have these studies.
And that's true even though there are only small numbers of animals in each of these studies, and in that connection I'd just like to say in response to your statement about how hard it is to do non-transmission studies in the future, this is a problem that we encounter in a number of settings with agents that are only transmissible to rare animals or animals that are very hard to obtain for one reason or another, and I'd like to at least suggest that even though it may not meet statistical requirements, the non-transmission studies in small numbers of animals can be done as long as you have suitable isolation, suitable challenge studies after the incubation period has passed.
And, again, even though it may not meet statistical criteria, it can be scientifically compelling.
DR. BROOKS: I think that's a fair comment. I agree with that.
DR. KUEHNERT: I just wanted to ask. This question was asked before by another presenter, but just about the issue about the presence of virus in cells versus freely evident in plasma, and you have the pro virus test you did. I'm not that familiar with it. Maybe you could explain that a little bit and whether all of the virus you saw was cell associated or whether you saw any in plasma.
DR. BROOKS: So to answer the question is that the provirus would represent integrated virus. In terms of foamy virus, some of it may be free virus which you're able to catch. The assay that we do is a commercially available standard methodology for extraction of total nucleic acid from whole blood.
Foamy virus, different from some other retroviruses, it's reverse transcriptions that happens early on so that a lot of the virus is already in its DNA form. So it may be technically free at that time, and it may be captured.
So my feeling is that the predominant virus that we're capturing is truly pro virus. That being said, the predominant virus we're capturing is pro virus that's integrated into the cells. Okay?
I think it's an excellent point you raise about presence of free virus in the plasma, and that is an ongoing part of our study. So we have those samples, and we're determining the best way of extracting them in order to answer your exact question.
DR. KUEHNERT: Thanks.
ACTING CHAIRMAN ALLEN: Yes.
DR. SAYERS: Will you take a question from the floor?
DR. BROOKS: Certainly.
DR. SAYERS: Thanks.
That one illustration that you showed changing CD4/CD8 ratios, revealing that the transfused monkey's immune response was not the same as the same as the control animal, do you think that might have been a different observation if the control animal had received uninfected blood rather than saline as its control?
DR. BROOKS: I think that's an excellent point you raise, and if I didn't mention it, I meant to mention it, that there are a number of possibilities that could explain that response. One, it could be just chance.
Another response, it could be related to just the transfusion in itself and have nothing to do with foamy virus. It may be as a result of foamy virus being present in the transfusion or it may be because of some other virus that we transmitted along with the foamy virus.
And so you make a valid point.
ACTING CHAIRMAN ALLEN: Other questions?
ACTING CHAIRMAN ALLEN: Okay. Thank you very much.
Our next speaker is Dr. Peter Ganz, regulatory considerations, the Center for Biologics' evaluation, Health Canada.
DR. GANZ: Good afternoon, and again, I'd like to thank the Advisory Committee and colleagues at FDA and CBER for an opportunity to talk a little bit about a snapshot in thinking at least of some of the regulatory issues surrounding simian foamy virus.
Next slide, please.
I'd like to focus primarily on some of the risk management considerations for prevention of transmission through blood.
As James indicated, this isn't a new issue, simian foamy virus certainly for Canada. We've had some discussions around simian foamy virus sine Dr. Sandstrom's and Dr. Brooks' earlier studies, and some of the data in the literature since 2001.
I wanted to show this slide primarily to indicate that although we're talking about simian foamy virus in the context of the blood system, there are, I think, broader public health issues that need to be addressed around simian foamy virus as well.
And, again, I think that certainly within our board federal government mandate in Canada, prevention of and managing the risks of the introduction of new adventitious agents into the human population is really a primary concern.
Just a couple of slides on the context, at least, from my regulatory perspective. Almost 300 different viruses, rickettsia viruses, rickettsia bacteria, fungi, protozoa. In helminth parasites are known to infect humans as zoonoses.
Many zoonotic infections do not spread further than the index patient, and many do not cause significant disease, except in compromised hosts.
Risks to the public at large are magnified obviously if the are vertical or horizontal transmission of an agent, and also certainly there is a further high risk of exposure in the population if there's transmission through transfusion and transplantation.
What are some of our general risk considerations with regard to simian foamy virus? Certainly there are three points to be considered with regard to virulence of pathogens such as simian foamy virus: time in dose of infection; the immune status and genetic variation of the host and the pathogen, and we heard a little bit about that in earlier presentations.
Some of the specific issues of concern are related to a well adapted host and parasite relationships which tend toward increasing virulence of the pathogen if we look back at other kinds of host pathogen examples, and also increasing incidence of immune compromised individuals in the general population, I think, is an issue as well.
Although at present we don't have an algorithm to say that if there's an infectious agent identified that this is the particular path we need to follow in terms of protecting the blood supply. Some of the consideration certainly that apply in our thinking are, you know, can the virus infect human cells, and we've seen data presented earlier that, yes, indeed, simian foamy virus does infect human cells.
Can the virus replicate and produce cell free infectious virus?, and again, there's data that says that that's true for simian foamy virus.
With respect to cell types that are targeted, again, the literature and in presentations today, it's pretty clear that the simian foamy virus has a very broad trophism, VNT lymphocytes, macrophage, fibroblasts, endothelial cells, kidney cells, and so forth.
Is the virus cytopathic or temperigenic in human cells? For simian foamy virus we heard Dr. Khan and Dr. Brooks mention cytopathic effects, and there's literature data on that. With regard to tumorigenic potential, again, as Dr. Khan mentioned, there doesn't seem to be any evidence at this point, unknown.
Can infection lead to human disease? And we've heard a couple of comments with regard to this particular issue for simian foamy virus. Insufficient data, certainly, and comments from presentations today are that the numbers certainly are low, and in terms of drawing conclusions from such low numbers is difficult.
Can the virus be transmitted from recipients? And, again, I think both the literature and in data summarized today indicate that yes for simian foamy virus within the non-human primate context, but insufficient data for humans. Certainly that's something, again, that given the low numbers, one has to be cautious in interpretation there.
Risk to the public, you know, in general. Exposure risk obviously is an issue in terms of persistence and transmissibility to other humans, multiple exposures, and an example I think was referred to in earlier presentations as well is the SIV. A number of instances where SIV has crossed into humans, and again, with one of these resulting in pandemic HIV Group M.
Another issue addressed abrupt changes obviously in biological properties that may occur when passing through a new species that may result in altered pathogenicity or transmissibility.
Passage through an intermediate host may provide or remove selective pressures, resulting in genetic modifications in viral adaptation, recombination within the host with similar viruses can also alter the tropism, virulence, and drug resistance patterns, and although naturally occurs because of very low frequencies.
In a mean compromised host, exposure to the virus may generally allow for persistent infections, which allows for viral mutations to accumulate over time, and we've had a couple of questions to investigators about that particular issue, and again, I think more research clearly is needed in that area.
So in terms of sort of the broad risk considerations on this particular issue, at least from our way of thinking, clearly there could be no risk. There may be insufficient evidence of risk, and there may be some evidence of risk, and that could range from both a low to a high level potentially, keeping in mind certainly within the regulatory context and perhaps broader than the regulatory context the need to act even in the absence of clear evidence is something I think that we all are -- certainly in the blood system is something that drives our thinking.
In terms of trying to distill some of the information certainly at least in our thinking in Health Canada, given some of the new data that we heard today and some of the data published in the Lancet earlier this year demonstrating transmission via transfusion, it seems reasonable for us that steps should be put in place to prevent transmission of simian foamy virus to the human population.
Now, what are the kinds of options that we could look at in terms of mitigating transfusion transmission risks in terms of broad spectrum options. One of them clearly is a public health measure, self-deferral. In other words, counseling individuals who have exposure risks either high or low to not donate blood.
Another option, donor screening and deferral, and this is one that we don't as regulars like to look at lightly. I guess the third bullet there, impact on blood supplies really are not listed in order of priority, but obviously that one is a very, very important one because we all understand how precarious supply issues for blood are, and clearly one has to balance a theoretical risk against the real risk of blood shortages. That clearly is a very important consideration.
There are still some other, I think, really difficult issues around an option for donor deferral, and that is that we don't really understand fully exposure risks in this particular area, and also even if we were to try and identify exposure risks, there is the issues around donor counseling and the more complex issues around any deferral action that we would consider that need to be further addressed.
Obviously donor blood testing is not an option at this point. The tests that Dr. Brooks and Dr. Sandstrom have developed in the labs, CDC, and Dr. Khan's are all research tests. There are no commercial tests at this point.
Another option is research and surveillance, which really isn't an option because that's why we're here today, and that's something that's ongoing with regard to simian foamy virus.
When we're talking about potential deferral measures, again, what are the types of risk exposure that we could try and define at this point in terms of broad groupings? Obviously we've talked a little bit about occupational exposure to non-human primates. That's biomedical researchers, animal handlers, veterinarians or zoo keepers. These are individuals which at least from the perspective of time and types of exposures, scratching, biting opportunities, these would be the ones that potentially would fit into a high risk category.
Nonoccupational exposure to non-human primates, we've talked. James showed some data on monkeys as pets in terms of the numbers, very, very rough numbers. We don't have numbers in Canada certainly, and the study on the bush meat, Cameroon data. So that may or may not be occupational exposure.
Incidental exposure to non-human primates, and again, we're not clear whether or not or how often that occurs, individuals who may have been bitten or scratched by a non-human primate. And perhaps there are other risk exposures that we're not aware of.
In terms of the way forward, at least our thinking within Health Canada is we have done some initial risk assessment that has been carried out by our Canadian Public Health Agency. We're refining that risk assessment to consider some of the data presented here today and some of the discussions from your committee.
We're having ongoing consultations with various stakeholders on this issue, including our blood operators, certainly if we move forward on any kind of blood deferral measures.
My last slide, just a series of acknowledgements to staff within Health Canada and our colleagues, Dr. Sandstrom and Brooks from Public Health Agency, for some of the thinking around this particular issue.
ACTING CHAIRMAN ALLEN: Thank you for that careful analysis. I think that was very helpful.
Where at this point do you see the Canadian Blood Services going in terms of addressing this issue? That's probably what you were addressing in your coordinated risk management efforts, but have you begun to reach a decision?
DR. GANZ: Well, I think actually that's something for them. I know we have some representatives from both CBS and HemoQuebec in the audience, and perhaps they are better able to address their thinking on this particular situation.
But obviously we're looking at, as I've mentioned in the slides, we are looking at a series of options. One option doesn't necessarily exclude the other one so that we can certainly pursue options on the public health side in terms of providing advice to exposed individuals to self-defer and not donate. That certainly would be complimentary to more stringent regulatory measures to the blood operators.
ACTING CHAIRMAN ALLEN: Dr. Klein.
DR. KLEIN: I have a narrow question and a broader question. Let me ask the narrower one first. Does the fact that you have universal leukoregulation at all influence the steps you might take in terms of safety in Canada? And this is a cell associated virus like CMV or HTLV.
DR. GANZ: Yeah, that's a very good question, Dr. Klein. And actually I was going to put it up on -- I used up my one slide on leukoreduction for the TSAC meeting.
Yeah, Canada has had universal pre-storage leukoreduction sine June of 1999. We implemented that particular process for a number of reasons, one of which was that it may afford some risk mitigation possibilities for any untoward agents transmitted through white cells.
So, yes, there might be some risk reduction already in the system, provided if the virus is white cell associated, but as you know, pre-storage leukoreduction isn't 100 percent effective. You're only reducing the titer of white cells marginally.
So, again, I'm not clear at all about infectious dose issues and so on with regard to this particular agent. Certainly in discussions with Dr. Sandstrom and with Dr. Brooks we'd like to pursue that particular issue through additional research, perhaps in the animal model system that James and Paul are using to look at whether or not, you know, components might afford different kinds of infectious dose.
DR. KLEIN: The broader sort of philosophical question is blood transfusion is a relatively small part of public health. If we all are so concerned about simian foamy viruses, isn't there an issue about screening the animals and perhaps preventing importation of infected animals?
It seems like the animal handlers are at much greater risk than transfusion recipients at this point.
DR. GANZ: Yes, you're absolutely right on that one. Absolutely, I think we need to look at that, and that's why I actually mentioned it at the start, to say that, you know, we're focusing on a blood system here, but there are obviously broader issues.
I think certainly the issue that I raised, that was raised earlier in the CDC presentation and by others is the issue of affording a broader opportunity for a non-endemic virus to spread in the population.
ACTING CHAIRMAN ALLEN: Other questions. Yes, Dr. Lerker.
DR. LERKER: If I could just comment on the broader question, there is a program now underway at least in some of the major research facilities housing non-human primates to breed and maintain colonies of animals that are free of simian foamy virus, among a number of different other agents, other retrovirus, other herpes viruses. It's a very long, arduous process to get a usable size of a colony going.
But if you tried to do that on imports, I think most of the animals, there would be no imports until things were implemented in the countries of origin. But probably where you were going with that. It is being discussed.
ACTING CHAIRMAN ALLEN: Okay. We'll move on to our last formal presentation: demographics of primate handlers. Dr. Nicholas Lerker.
DR. LERKER: Thank you very much. I'm pleased to be here today to talk with the Advisory Committee.
I'd like to try to do two things as the final speaker in this series. One is to try and address the issue of what kinds of numbers of individuals we're talking about when we talk about significant or exposure to non-human primates.
And then finally, I'd like to give the Advisory Committee perhaps a little insight into animal handling techniques over the years and how that can contribute to some of the human exposures that we're seeing the results of.
Next slide, please.
We know from doing individual jobs specific risk assessments in our own facility and others, as well as some epidemiologic data that we published back in 1996, that there is differential exposure to both live and awake non-human primates as well as their body fluids, tissues, waste products, and so this is some of the demographic data that has importance in determining the significant risk categories.
Some of the job categories that we've tried to address individually are the veterinarian pathologists, animal, both husbandry and health technicians, biomedical researchers, behavioral observers, laboratory technicians, and then pet owners which don't necessarily fit into the occupational program, but I put them up here for analogy to some of the other categories.
In our epidemiologic studies, we found that obviously veterinarians and husbandry technicians were the most likely to handle live, non-human primates, and therefore, they're at the highest risk of the animal inflicted bite and scratch wounds.
In our epidemiologic study we found that the animal health techs were significantly more likely to be bitten than any other job categories. Veterinarians were significantly more likely to suffer body fluid exposure to mucous membrane. So there is some differential risk associated with the different job categories.
I put the proximity to primates up here just for a point of discussion, and it was touched on by at least one of the earlier speakers, but this is significant just if you spend a lot of time around primates, you will know that -- I speak from experience -- that some species of primates are quite adept at spitting either saliva or mouthfuls of water at humans and also can throw feces with great accuracy over long distances.
DR. LERKER: And as I said, I can speak from experience with that, and these are primarily the apes. Chimps and orangutans are quite good at that.
So even somebody with sort of remote or distant approximation to non-human primates is not totally without risk. So I'd leave it there.
Just one other point I'd like to make is that in terms of the exposure opportunities for both the primate itself and its body fluids and feces and so on. The pet owner's profile resembles that of the two other high risk categories, the veterinarian and the animal health technicians.
Next slide, please.
Now, one of the problems is that in trying to determine the numbers of people that we're talking about in this discussion is these data are not readily available, and the approach that I have taken is to employ some enumeration methods, and what I've tried to do and I'll share with you is develop a sampling frame, and this is a specific initially for occupational exposures, a sampling frame that is organized by facility type.
And the rationale behind that is that facilities housing non-human primates that are a similar type probably have similar staffing ratios and so on. So at least for a first analysis, that's what we're trying to get a handle on.
Then we survey a subset of these facilities within each of the categories and try to get some idea of the numbers of workers in each job category, and then by applying those numbers from the subset to the larger sampling frame, we can get some data on the numbers that we're talking about.
This is the approach I've tried to use, and I should say at this point that this is very much a work in progress, and much of the data that I'll share with you today I got within literally a week ago at the meeting of the Association of Primate Veterinarians, and so this is data that's still being developed.
Next slide, please.
So this is the sampling frame that I've developed, and this is the types of facilities that I've identified. This is the National Primate Research Centers funded by NIH, academic institutions, contract research organizations, various institutes and foundations, the big pharmaceutical companies and biotech.
Primate sanctuaries, this is a growing, increasing number of these facilities which provide sanctuary for primarily unwanted pets or former research animals, and it is a distinct entity from zoos, but there is a growing number of these facilities.
And then government and military research institutes. The vendors who provide monkeys for research and other purposes and importers, and then there are at least three commercial diagnostic laboratories that specialize in testing non-human primate samples, and so they are by definition exposed to the non-human primate body fluids.
And then among the zoos, 200 zoos, there are quite a few more than that in the U.S., but at least 200 of them have at least one species of non-human primate on exhibit, and these are the estimated number of the types of facilities in the U.S. So they have identified so far at least 374 facilities in the U.S. that house non-human primates.
So this is a busy slide, but this is the same from the previous slide, and this is the number of subsets or the subset of different types of facilities that we have been able to survey over the last month or so.
And then in parentheses, it's just a percentage of the estimated total. So we have actually gotten data from 47 facilities representing at least one sample in each of the categories in the sampling frame.
And what this has allowed us to do is determine the mean number of workers in each of the job classifications of interest, in other words, veterinarians, pathologists, technicians in a broad sense, and biomedical researchers.
So to cut to the chase, what kinds of numbers are we talking about here? Using this approach, and again, this is preliminary data, we have identified a potential of 14,500 individuals among all of the job categories who are exposed or have contact with non-human primates. If you look at the two high risk groups, the veterinarians and the technicians, the number is around 10,000.
Now, some of this may change. I didn't mention it, but on the previous slides where we have estimates of the average number in each of those categories, some of the confidence intervals are quite wide, and as we gain more data and sample more or survey more subsets, this data will change, but I don't really foresee any huge alteration at least orders of magnitude different.
So I think this is a reasonable ballpark figure for the total number of persons exposed to non-human primates in an occupational setting.
Now, I want to revisit the pet issue again because this is really the big variable in the equation in my mind. There's very little data in terms of the numbers of pets maintained or animals that are being maintained in private ownership, and I use the term "pets" to include other types of private ownership. There's quite a few non-human primates that are in the entertainment industry, and you have probably all seen primates in movies and so on. So that's sort of what I'm talking about here in the broader term when I refer to "pets."
Many states have absolutely no regulations regarding the maintenance of non-human primates as pets, and even those that do have exemptions. California, for example, has one of the most stringent regulations regarding having non-human primates as pets, and new acquisitions have been banned since 1973 or around that time, but at that time they grandfathered in a lot of people who already owned these animals.
And so there are existing pockets of these animals, and their offspring are also exempt under the grandfather clause. So even in States like California, there are a fair number of animals, but an unknown number of animals maintained as pets.
There has been one single estimate that I've found, and this was referred to earlier, I think, in the opening remarks about the number of animals maintained in households in the U.S., and this is quoted to be or estimated to be about 15,000. This comes from a National Geographic article that they did on the non-human primate pets, and the quote is attributed to someone in the primate sanctuary business, and some of this was based on the number of phone calls that sanctuaries were receiving by people looking for some place to take their pets off their hands because these animals are quite cute when they're young, but they are very unpredictable and become aggressive when they become sexually mature.
So the novelty wears off. These animals need someplace to go, and so the quote comes from that kind of assessment. Though it has not been verified or the accuracy, I haven't seen any real surveys about the accuracy of this number, but it's a working number for purposes of discussion.
The other question then is how many contacts are there in each household, and this is the highly variable issue. If you just assume there are 15,000 households and a minimum of two persons per household, then there's 30,000 individuals right there.
So the pet issue is quite the unknown in this whole equation.
And I just include this. We saw earlier Jane Goodal with the chimp, and this is something that I got off the Internet, and if you look on the Internet there's quite a bit of traffic in non-human primates in the pet trade or exotic animal trade.
And looking at that, this doesn't seem too unreasonable, but I just wanted to show that it's not just new world monkeys that are available and kept as pets. This is a baby baboon here, and this is a puppy, and similar to the quotation about pornography, if we're trying to define significant contact, it may be hard to define, but you know it when you see it. That is significant contact with an old world species.
This just shows the distribution of some of the major species in the facilities. Again, returning to the occupational side of things, chimp, baboon, African green monkey and macaque were the common old world, and virtually all of the facilities house macaques. Number of them also house chimpanzees.
And the human cases to date have all been where the species of origin has been identified, have all come from old world monkeys. No new work monkey infections have been identified as yet.
Now, I just want to shift. Well, just one other comment on the numbers impacting on the blood supply. At the break I got some information since I'm really not up to speed on what would be a significant impact on the blood supply, and I'm told that there was an estimated 50,000 donations per day. The small number of humans here would be less than two days' worth of donations.
So at least from my own perspective or that at least puts things in perspective for me.
Finally, I want to talk about some of the trends and changes in animal handling that have occurred. One of the continuing areas to evolve are the use of personal protective equipment, and there is a large disconnect or some gaps in how things get done in different facilities.
For example, in the research end of things, full PPE is the standard operating procedure, and by this I mean gloves, long sleeves or Tyvek sleeves that are shown here, the dedicated uniform that is not worn off the premises, dedicated shoes or shoe covers, a face mask and eye protection, either goggles or a face shield. So this is sort of one end of the spectrum.
And the research facilities for the most part adhere to that end of the spectrum. The face shield issue was taken much more seriously in the mid-'90s, actually the late '90s, 1998, I believe, following the tragic death of an animal handler at one of the national primate centers from an ocular splash from a monkey shedding B virus, Herpes B or cercopithecine herpesvirus 1.
So I'll show the sort of evolution of where we are today in a moment, but the face shield issue and the whole issue of personal protective equipment in the research setting took on new meaning in the late '90s.
Zoos and sanctuaries appears somewhere in between on the spectrum. They may wear gloves and dedicated uniforms, but have not adopted the full personal protective equipment at least across the board.
Now, there is a new guidelines that have been issued or are out for review by the occupational health group of the American Association of Zoo Veterinarians, and so the zoos are moving more in this direction, at least in doing risk assessments and, for example, wearing eye protection when hosing is being done or handling of animals and so on.
At the other end of the spectrum, the animals in the private sector, very little, if anything, is being done in the way of personal protective equipment.
This just shows some of the evolution of the use of personal protective equipment over the years, and I was rereading some of the case reports and some of the original cases that reported bite wounds that occurred back the '70s and '80s, and you'll see why infection might be more likely to have occurred back then.
This shows some technicians that are restraining unaware, unanesthetized adult Rhesus macaque for tuberculin testing, no gloves, bare forearms, no eye protection, no mask. So bask in the '70s, that was the standard.
In the '80s we adopted the use of gloves for handling primates. In the '90s we added masks, and then in 2003, again, the eye protection although it doesn't help when the primate removes your eye protection for you.
DR. LERKER: But this is sort of the trend to more eye protection or more personal protection over the years to the current state.
This just shows again some of the animal handling trends over the years. Again, back in the '70s, people hand feeding macaques without any protective equipment whatsoever. Hand catching of primates was common in the '80s, into the middle and late '80s. The animals would be captured, removed from their cages using these heavy leather gauntlet gloves, and then the animal would be restrained and then the gloves would be discarded in favor of these vinyl or latex gloves.
And so you can see that learning this technique was not without risks, and so bites were very frequent and these gloves would not protect against a bite from an adult macaque with full canines regardless.
So we have moved away from that now, and we use a lot more of animals that are trained to jump into a transfer box. Again, the full protective equipment that's being used, and so the trend has been to more and more protection. So hopefully the risks associated with working with non-human primates now are not the same as they were in the '80s and '90s.
Just in conclusion then, what can we say about the numbers or the estimates? Again, it's a work in progress, and I think it's valuable that we're -- it was eye opening to me about how difficult it is to get this kind of information and I think we'll move forward and try and get a more complete view of the number of people exposed to primates both in occupational settings and as pets.
One of the things I wanted to mention and I forgot to mention when I talked about the calculations of the numbers. That only takes into account the staffing as it exists last week. It doesn't account for the turnover of people moving through these facilities, and there is quite a high job turnover in some of the positions at high risk, particularly animal technicians are from these entry level technicians, and people spend a short period of time and go elsewhere, and so there is a cycling of people potentially exposed and then moving on to other jobs that would not be captured in the kind of analysis that I showed you earlier.
And then finally just to hopefully -- current handling practices at least in the occupational setting should reduce the risk of the exposure, but not eliminate it completely.
So I think I'll stop there and answer any questions you might have.
ACTING CHAIRMAN ALLEN: Thank you very much, Dr. Lerker.
Questions? Dr. Lew.
DR. LEW: I don't know if you can answer this question, but I was just thinking about different cell lines. We use a lot of non-human primate cell lines in the laboratory, you know, for evolved cultures, all sorts of things, and I'm assuming that people are aware, but I don't know, you know, of the simian foamy virus problem. Is it possible that it's in different laboratories and that's another occupational exposure?
DR. LERKER: Yes, I think there are a number of cell lines that could harbor foamy virus. Most of our experiences that even in primary cell cultures where it's a problem, in fact, most of the attention before the recognition of the human cases, most of the attention to foamy virus was to get rid of it because it's a nuisance. It destroys continuous cell lines. You can go out maybe two passages and then the latent virus reactivates and you get a lytic infection that wipes out your cell line.
So there are cell lines, I think, that can harbor it. Also, some of the cell lines that apparently have that delayed, they don't have the predictable re-activation and lytic infection that they still are infected. I don't know what ATTC does to screen their primate cell lines for foamy virus, but some of you might know that.
DR. LEW: The other follow-up question is has anyone looked to see if there was seroconversion of people that have worked for years with these different cell lines.
DR. LERKER: To my knowledge, they have not specifically looked at laboratory workers having worked with the cell lines for a long period of time.
There is one case that's associated with a laboratory exposure, but I believe that was primary monkey tissue and not a continuous cell line. So I don't think that has been done.
DR. KUEHNERT: Thanks for the presentation. It was very interesting. I just had a couple of questions.
One about, you know, you mentioned how PPE has changed over time, and I wondered if there were any data on actual needle stick and bite injury rates, whether that has actually changed over time along with the changes in practices.
DR. LERKER: We did a follow-up to our study that we did in 1996. We haven't published this, but we're gathering data. The bite rate has declined, which is good news at least in our facility. This is our facility.
The needle stick rate has remained about the same, and one of the interesting differences, for example, if you compare the needle stick rate of, say, a primate facility to a hospital, there's a different -- most of the needle sticks occur in the primate facility while the needle is in use rather than after use where it has been discarded, and this is because the primates move and jump and so on.
So that's one slight difference. I don't know if it makes any difference to exposure necessarily. But the needle stick rate has been fairly constant over the interval. So we need to think more about that as a risk factor.
DR. KUEHNERT: The other question I had was just about looking at the data, SFV and affected workers, that it looked like that people were first seropositive a while back, and so I wondered whether there are data on people who have only worked in the field since PPC was significantly changed and the techniques have been changed in the last ten or 15 years.
DR. LERKER: Well, I think that this could possibly be gleaned from the ongoing study that CDC is doing because they include a variety of people with a large -- what do I want to say? -- work history. I mean some have worked for many years. Some are very new.
One thing also I didn't see in our earlier study, we did find that the incidence of accidents associated with non-human primate exposure in our study was much more or significantly elevated in people who had only been working less than two years.
And even with that frame, it's significantly higher in people who had worked six months or less, and so there's some kind of experience on training curve going on there.
But that's a good question. I think that will come out or could come out in the study that CDC is doing because they're getting histories on length of time exposed, I guess is what I'm saying.
DR. HENEINE: If I can add to what Nick just said regarding the duration of seropositivity, in our cases it is true that the majority have really longer durations, especially when samples are available for testing. But we did have a recent case where the duration was short, suggesting recent infection.
So we cannot fully exclude the possibility of recently acquired infections as well.
ACTING CHAIRMAN ALLEN: Other questions?
ACTING CHAIRMAN ALLEN: Okay. Well, thank you very much, Dr. Lerker.
The official timepiece says 1600, four o'clock. Why don't we take a break for 15 minutes? We'll come back and have the open public hearing. I've only got one person who is scheduled to speak, Dr. Kleinman again, and then we will move to the open committee discussion.
So we'll recess for 15 minutes.
(Whereupon, the foregoing matter went off the record at 3:54 p.m. and went back on the record at 4:17 p.m.)
ACTING CHAIRMAN ALLEN: We're ready to move into our open public hearing.
Is Dr. Kleinman in the room? Ah. Thank you.
Okay. Is there anybody other than Dr. Kleinman and his joint statement who would like to speak on this issue in the opening hearing.
Okay. Steve, I apologize. I need to read the statement to you for the third time today.
Both the Food and Drug Administration and the public believe in a transparent process for information gathering and decision making. To ensure such transparency at the open public hearing session of the Advisory Committee Meeting FDA believes that it is important to understand the context of an individual's presentation. For this reason, FDA encourages you, the open public hearing speaker, at the beginning of your written or oral statement you advise the Committee of any financial relationships that you may have with any company or any group that is likely to be impacted by the topic of this meeting.
For example, the financial information may include the companies or groups payment of your travel, lodging or other expenses in connection with your attendance at the meeting.
Likewise, FDA encourages you at the beginning of your statement to advise the Committee if you do not have any such financial relationships. If you choose not to address this issue of financial relationships at the beginning of your statement, it will not preclude you from speaking.
So if the Chimpanzee Owners Association of American have paid you anything, please let us know.
Good afternoon. Dr. Steve Kleinman, Chair of TTD. And it may amaze you, but on this issue I have no financial conflicts.
So I'd like to read the joint statement from AABB, American Red Cross and America's Blood Centers.
SFV infections in humans has been recognized for a number of years. Newer studies have confirmed that humans working with primates in zoos or in research institutes in the U.S. may acquire this infection. It also appears that primate to human transmission has been occurring for many years in areas of Central Africa.
Because of the past experience with other simian retroviruses developing into human pathogens, and we have HIV-I, 2 and HTLV, AABB, America's Blood Centers and American Red Cross believed that continued concern over and study of SFV as a potentially transfusion transmitted pathogen is warranted.
Current knowledge indicates that SFV infects human peripheral blood leukocytes and establishes a persistent infection, and it can be detected for over 20 years. SFV does not appear to cause disease in humans, although the number of chronically infected persons undergoing follow-up is limited, I guess I would say very limited from what we've heard today.
Data about human-to-human transmission of SFV are sparse. Sexual transmission has not occurred in six couples. And transfusion transmission did not occur in four recipients of blood components from a single SFV chronically infected donor.
There are many unknowns about potential transfusion transmission in humans if it occurs. As a high cell associated virus, it is possible that SFV will behave similarly to HTLV, such that one storage of red cells beyond 10 to 14 days would eliminate transmission. Two leukoreduction would greatly reduce if not eliminate the transmission risk from chronic carriers. And three, there would be no transmission from FFP cryoprecipitate or fractionated plasma derivatives. These possibilities could be tested in an animal transfusion transmission model, although there are some limitations in demonstrating lack of transmission as we've heard today.
There have been no studies of the prevalence of SFV in the U.S. blood donor population. Based on a limited number of research studies some broad risk factors can be defined including close physical contact with primates in the wild in Central Africa or in zoos and research institute outside of Central Africa. It is unclear if increased risk extends further to persons with more limited primate contact.
It should be noted that the current donor history questionnaire includes a question about previous residence in Central Africa, which appears to be a possible risk factor for SFV infection. Although it has been anticipated that this question may be discontinued as blood centers begin using laboratory tests capable of detecting HIV-1 group O.
In summary, limited current data suggests that SFV does not appear to be pathogenetic for humans. The prevalence of the agent in U.S. donors is unknown, but would be suspected to be very low. Transfusion transmission in humans has not been demonstrated, and if it were to occur the potential for detectable effect of leukoreduction and the risk from plasma products have not been assessed.
With the exception of definitively assessing the potential for SFV to be a human pathogen, we believe that the answers to all of these above questions could be obtained by performing well defined research studies.
Now, on a slightly different tack, in its investigations the CDC has adopted a policy of counseling SFV infected subjects to not donate blood tissue or other biological material. We agree with this approach. However, the deferral of a known SFV infected person is a very different issue than adopting a deferral policy based on an attempt to establish an epidemiologic risk profile. Until further information is available, AABB, ABC and ARC believe that no additional questions should be added to the donor health history questionnaire. This document is already extremely long and complex and the addition of more questions with unknown benefit runs the risk of distracting donors from my more risk questions.
Furthermore, at this point it is unclear what criteria should be adopted to identify SFV risk and how a question could be worded to elicit such accurate information from donors.
ACTING CHAIRMAN ALLEN: Thank you, Dr. Kleinman.
Any questions for Dr. Kleinman on this statement? Okay.
Dr. Tabor, are you presenting the questions again formally or --
DR. TABOR: Could I ask for the last three slides in my presentation case?
The first question: In the absence of any known disease association should FDA be concerned about the potential for transfusion transmission of SFV?
ACTING CHAIRMAN ALLEN: Comments, discussion on this?
DR. LEW: I think it's a given we don't have enough data now to say if it's truly pathogenic. So, yes of course we should be concerned.
ACTING CHAIRMAN ALLEN: And I guess I would add to that that certainly in highly susceptible populations, i.e., for example people who are immunosurpressed, that is important. And we probably are using SFV simply as a place holder for other viruses that may be similarly transmitted, some of which we may know about and some of which we may documented in the literature that we were provided to read, and some of which we may not yet have identified. So, I would certainly agree with your summary statement.
Other? Dr. Cunningham on this?
DR. CUNNINGHAM-RUNDLES: Well, I guess the problem for all of us is going to be what does concern translate into to. So concern sure, but concern is kind of like not specific worry. So that's obviously got to have a second question: Okay, what do you do about that? What can you do to solidify that concern into some fact.
ACTING CHAIRMAN ALLEN: Dr. Tabor, do you want to go ahead and run through all three of the questions.
DR. TABOR: Yes. We can go all through the questions.
Let me just add that I think that some of the thinking behind this question was at the last BPAC meeting it was felt there was not enough data to be concerned yet.
So let's go to the second question. Next slide, please. Do the recent evidence of SFV infections in humans and the evidence of transmissibility of SFV by blood and animal and animal studies heighten concern that known and unknown pathogenic viruses of nonhuman primates could enter the human blood supply?
And the next slide, please. Number three: Do the available scientific data warrant possible consideration of donor exclusion criteria for exposure to nonhuman primates? Please discuss the factors that should be considered.
Why don't we go back two slides, please.
ACTING CHAIRMAN ALLEN: Other discussion on question one? Attempts to define the word "concern."
DR. DOPPELT: I just was going to say something similar. I think basically what your concern is a watchful eye. I mean, you're going to try and be observant, collect data. But right now you don't have much to hang your hat on, so --
DR. TABOR: Without focusing on the word "concern," the real question is does the Committee feel that the science suggests that actual transmission of SFV in the blood transfusion studies is an issue that we should be dealing with?
ACTING CHAIRMAN ALLEN: I'm going to go back to Dr. Kleinman's statement, the joint statement, and pick up -- this is on the second page, the second full paragraph the last full sentence. And he's listed some of the information that is known and some that is not known that should be known and then concludes: "With the exception of definitively assessing the potential for SFV to be a human pathogen we believe that the answers to all of these above questions could be obtained by performing well defined research studies." And I certainly would translate the word "concern" to be yes I think it needs attention. We need to continue with all of the appropriate agencies of the Public Health Service, including certainly the FDA and its regulatory authority, the Centers for Disease Control, the NIH to be aware of this potential and continuing to monitor the situation very carefully and to fund and conduct research studies.
so, I mean, that's how I would translate "concern."
Yes, Dr. Klein
DR. KLEIN: I was just going to say that just the TT virus and GDBC and a number of other viruses were on the radar screen. This now, obviously, needs to be on the radar screen. And I quite agree that we need to not only continue to do the kinds of epidemiologic studies, but also the interventional research studies that are important until we can determine whether this is something that is a public health issue.
ACTING CHAIRMAN ALLEN: Dr. Goldsmith?
DR. GOLDSMITH: I guess I take a more cautious point of view than what I've heard here so far in a sense that this is a simian retrovirus and we already know about some of those as they're crossed the line from primates, from nonhuman primates to humans. They've caused different kinds of disease in humans, and some have had long latency. We have heard about HTLV-1 today. And this could be a similar kind of an agent and that we haven't looked at long enough or in depth enough.
So I guess concern to me would be yes I am concerned. I would vote for being very concerned. And we'd like to have some additional information. And if by saying that we're concerned about this in the public forum, would that help people that CDC or elsewhere get more information from the public or get their job done quicker, then I think we should all be in favor of saying we're concerned and vote for that.
DR. TABOR: Could I just add? We've heard actually some good suggestions about areas for future research that come up in the discussion. I would just like to point out that this subject, this Simian Foamy virus ad blood transfusion and perhaps just Simian Foamy virus in general is most of the research is being done, most if not of all the research is being done in government laboratories. And this really is one of those things when people say what should we be doing research on in the government, we should be doing research on what no one else is going to do, that the private sector is not going to do. And this is probably one of those areas.
ACTING CHAIRMAN ALLEN: Are we ready to vote on question one?
Dr. Smallwood, would you --
DR. SMALLWOOD: All right. According to procedure, we must take a call vote.
DR. HARVATH: Yes.
DR. SMALLWOOD: Dr. Nelson?
DR. NELSON: Yes.
DR. SMALLWOOD: Dr. Cunningham-Rundles?
DR. CUNNINGHAM-RUNDLES: Yes.
DR. SMALLWOOD: Dr. Kuehnert?
DR. KUEHNERT: Yes.
DR. SMALLWOOD: Dr. Quirolo?
DR. QUIROLO: Yes.
DR. SMALLWOOD: Dr. Hollinger?
DR. HOLLINGER: Yes.
DR. SMALLWOOD: Dr. Goldsmith?
DR. GOLDSMITH: Yes.
DR. SMALLWOOD: Dr. Schreiber?
DR. SCHREIBER: Yes.
DR. SMALLWOOD: Dr. Lew?
DR. LEW: Yes.
DR. SMALLWOOD: Dr. Klein?
DR. KLEIN: Yes.
DR. SMALLWOOD: Dr. Doppelt?
DR. DOPPELT: Yes.
DR. SMALLWOOD: Dr. Davis?
DR. DAVIS: Yes.
DR. SMALLWOOD: Dr. Allen?
ACTING CHAIRMAN ALLEN: Yes.
DR. SMALLWOOD: And Dr. Strong, your opinion?
DR. STRONG: Yes.
DR. SMALLWOOD: Thank you.
The results of voting for question number one was a unanimous yes.
DR. TABOR: All right. We will proceed with discussion of the second question. Do the recent evidence of SFV infections in humans and the evidence of transmissibility of SFV by blood in animal studies heighten concern that known and unknown pathogenetic viruses of nonhuman primates could enter the human blood supply?
ACTING CHAIRMAN ALLEN: Dr. Hollinger?
DR. HOLLINGER: Yes, I think I understand the question. But we already know that. I mean, you got SIV and going to AHIV, you have STLV and HTLV. So when I read this initially I thought this is something we already know of the issue. And so I'm not sure on how it helps the question.
Tell me what you're looking for in this?
DR. TABOR: Well, you know, I can't disagree with you when you say we already know about SIV and STLV. But when this report came out in March of 2004, it was accompanied by a commentary that raised the specter of cross species transmission beyond what we already expected. And so what we're asking you is -- what we're really asking you is should we be doing something based on a scientific understanding that this model could represent cross transmission that's occurring or could occur with other viruses? In other words, should we -- it really leads into the third question which has to do with types of donor exclusion. The question is do you feel that this model could represent a risk from cross species transmission from any of a variety of virus.
It looks like Dr. Epstein wants to add something.
DR. EPSTEIN: I think what we're really getting at is let's say we determined with some level of certainly or confidence that Simian Foamy virus is not a human pathogen, would we want to screen anyway because of a surrogate value for other things we might be concerned about known and unknown? So we're really asking an opinion about sort of index of concern on the surrogacy question.
DR. NELSON: Well, by screen you mean incorporate this antibody screening donors? What do you mean?
DR. EPSTEIN: Well, we're not directly asking the Committee should we screen now for Simian Foamy. But we're saying would the issue of it being a marker for settings of risk for acquisition of simian pathogens be reason enough to develop a screening or testing program for Simian Foamy.
DR. TABOR: When you use the word "screen" though, Jay, I interrupt it a little bit more broadly. That could include a donor question.
DR. EPSTEIN: That is correct. In other words an intervention strategy. Is an intervention strategy for Simian Foamy, should we be considering intervention strategies for Simian Foamy because it may represent a marker for risk for other Simian zoonoses?
DR. HOLLINGER: Well, again, I think until you have a disease -- I think that of that commercial where is the beef. I mean, until there's a disease that one's established or that you have some association with a disease or an association with some other retrovirus that's really substantial, I don't think you could do anything with that.
It says that we should probably continue some of the studies that have been outlined here today to look for these associations. That's very important. And one may or may not find any disease association whatsoever, but I think you have to look for it. And until that's the case, then I think this doesn't help us at all.
ACTING CHAIRMAN ALLEN: Let me disagree very slightly. And I agree that it seems like an obvious conclusion. Given the way that the government works, a positive response from the Committee on this is also a public statement from an expert committee in terms of adequate resources and allocation of resources. And that may be of assistance to the FDA if the committee believes that that's worth making such a statement.
DR. KLEIN: I guess I'm slightly more concerned that this is an old world primate virus than I am that it's, for example, a porcine virus. But I am concerned about porcine viruses. I'm concerned about avian virus as well, and other animal species jumping the barrier. So in general, yes, I think I'm a bit more concerned about this. But I agree with Blaine that I think we should put resource into looking at this virus. If you asked me how I would address the issue in general, I'd like to put a lot more resource into pathogen reduction technology for cellular blood components so that we could address all of these things rather than just this individual one.
So I think the answer is yes, I'm marginally more concerned at this point because it is an primate virus, but I'm still concerned about all of these others that we know can cross the species barrier and we know that some of them can cause human disease.
ACTING CHAIRMAN ALLEN: Well, but as I read this question it says "known and unknown pathogenic viruses of nonhuman primates that could enter." I mean, it does go beyond just the Simian Foamy virus.
DR. KLEIN: If they just to contrast the nonhuman primate, I am very concerned about those. But I am also concerned about other animal viruses. And so I think, you know, where do you start and where do you stop? Are you going to screen animal handlers out of the blood supply? How about pig farmers and chicken farmers? Again, I think the strategy probably is not to in the direction from my opinion, but to look at pathogen reduction and put a lot of resource into this one that we're aware of now.
ACTING CHAIRMAN ALLEN: Dr. Strong?
DR. STRONG: I would agree with the yes answer to support research, which I think is the primary issue here. As Dr. Lew has mentioned, we don't have enough data to really say that this is a big problem.
I'd be a little concerned, though, by saying yes we're saying you should do something about the blood supply at this point in time. I think there's not enough data to support that answer.
DR. QUIROLO: I didn't really hear any data to support that this was a surrogate either. I mean, it seems to occur by itself. There's no other viruses associated with it that I -- unless I missed something.
DR. LEW: Well, I know there's no data that's been presented, but it's the unknown. If we did see Simian Foamy virus transmitted and you know that it came from a nonhuman primate source, so blood-to-blood there's always a possibility of that unknown. I think that's the only thing -- the way the question is read, that's what I'm assuming it's trying to address. But I do agree that we all want more research, just not enough data to say let's change how we do things with the blood banks.
DR. QUIROLO: Yes. I'd hate to see screening for this because people were afraid it was a marker for something else, like we've done in the blood banking business in the past.
ACTING CHAIRMAN ALLEN:
DR. HOLLINGER: I did not read the question in that way.
Dr. Epstein, do you want to make any clarifying statements or --
DR. EPSTEIN: Well, I don't know if I'm adding clarity or confusion. But I think the idea of question one was is Simian Foamy a concern in its own right? In other words, what's the threshold of concern? And I heard that there's enough concern to keep it on your radar screen and do more research.
Question two is Simian Foamy further a concern because it might a surrogate for other things we might want to be worried about that could come from primates? And I'm hearing mixed opinions, and that's fine. But I do think they're different questions.
DR. TABOR: I wonder if I could also try to put it in a slightly different context, but I want to be careful not to indicate any kind of regulatory approach. Because we haven't really discussed this beyond the preparations for BPAC.
First of all, there is an atmosphere in the blood community of wanting not to be behind the eight ball, but be out in front and be proactive with regard to emerging infectious diseases. And we've all heard discussions about whether things would have been different if we had had some measures in place, if we could seen the future before the AIDS virus entered the blood supply.
And the question here is are we -- and this was really, in a sense, raised by the Lancet commentary. Are we seeing a marker for what is going on and we haven't detected yet in seeing Simian Foamy virus cross species not really nonoccupational conditions, but more casual conditions than just between animal handlers and animals?
So if you were leaning toward adding a question or some kind of donor exclusion, the meaning of this question is would you do it solely on the basis of it as a model for other unknown viruses?
ACTING CHAIRMAN ALLEN: So you are asking whether populations at risk for infection by this virus represent the high risk behavior we ought to be concerned in the context of virus behaviors?
DR. TABOR: I wouldn't word it quite that way, but I think we're really asking whether populations that are exposed to this virus are a high risk population for other retroviruses because of their contact. So in a way that's what you're saying, but with different words.
ACTING CHAIRMAN ALLEN: Dr. Kuehnert?
DR. KUEHNERT: I'm not sure if this is what you're partially getting at, but if we turn the clock back 30 years ago and had this same discussion and then became concerned and instituted a deferral for all these animal handlers and pet owners, it wouldn't have done a thing to stop the HIV epidemic. So I'm not arguing against a deferral. I'm just saying that that's not going to stop a global pandemic. We need to be focused on transmission through blood rather than overall public health strategy. At least for this question.
DR. QUIROLO: Dr. Nelson?
DR. NELSON: Yes. I was just thinking about what Harvey said. I agree. I mean, there are a whole range of animal to human viruses, some of which are known to be quite pathogenic. And, you know, we could divide a fairly complex algorithm of screening excluding all kinds of occupations. I mean, hepatitis E and, God knows. And it is worrisome that this is a primate, but nonetheless until I think we find either more evidence that it is a surrogate for a class of viruses that we could use it that way or in itself has even subtle pathogenicity over a long time.
One of the things that I think should be done is if there's pathogenicity, it may be quite slow and it would be interesting to find people who had been infected for quite a while, decades, and look what has it done to their hemologic system or what have you. And it might be possible to do that. I mean, that approach was taken a little bit with HTLV-1 and 2 short of the leukemia thing that eventually it was demonstrated that there was other potential for pathogenicity which made it important. Initially we didn't screen for HLV-2, but it was after some observation that we found that there was a reason. But there are a whole group of other viruses, even possibly some of the others that have recently been described. Under certain circumstances they're at least associated with pathogenicity, and the evidence is probably stronger than for these simian viruses.
DR. KLEIN: I must say I like the idea of getting rid of cell associated viruses because they're getting rid of ones that we know are pathogenic, even though CMV isn't an enormous problem, it is a problem. Yes. And at the same time you're going to probably get rid of this particular virus, although that remains to be determined. So I guess as a surrogate measure I'm more in favor of getting rid of cell associated viruses than excluding people who may come in contact with primates now. I mean, next month it might change. You have new data.
ACTING CHAIRMAN ALLEN: Well, I guess it's that kind of thinking that lead me to read this question as being more of a research type question. But I've heard other discussion that suggested that maybe it's more of a regulatory type question. And I think that's a point I guess needs to be clarified before we actually vote.
The other point, you know we have had extraordinary evidence in the last three years in the United States of the potential for viruses to cause transfusion transmitted infection in a way that was never previously conceived. I don't think most people would have suspected the West Nile Virus, for example, could transmit and cause the disease that it did. And a tribute to our technology and to our surveillance systems now that we were able to pick that up so quickly, do the investigations that were done and get a laboratory screening mechanism in place.
You know we are going to learn a lot more now because of the tools available to us compared with where we were 20 years ago.
DR. KLEINMAN: Yes. My sense of this model issue, a sense of the discussion on this topic is actually the reverse of what we're talking about. And that is the reason that we're more concerned about SFV than we would be otherwise is because we've had the examples of SIV and STLV. I mean, if we just looked at SFV in itself and we didn't have these other retroviruses that had jumped and caused disease in humans, we would say there is no evidence of disease. And we're not linking it to other viruses that have disease, so therefore our level of concern wouldn't be anymore than it is for STLV or TTV, it's another virus. Lots of viruses are transmitted in the absence of pathogen inactivation. And we don't have technique to worry about all of them.
So I think we're actually being influenced by the fact that the reason we're not comfortable with the data on SFV is because we have precedents of other retroviruses causing human disease. And we're sort of saying well maybe SFV, even though we don't think it causes disease, we can't really be sure. It might mutate and do the same thing.
So I don't see how SFV becomes the model for unknown pathogens. I see that SIV and STLV is the model for thinking about SFV as a potential pathogen in the future.
ACTING CHAIRMAN ALLEN: Other discussion on this second question?
Can I ask, just before we vote, can we have a quick show of hands among the Committee members who would like to see this interpreted more as a research oriented question versus a regulatory oriented question? Is that helpful at all?
DR. EPSTEIN: I think that confounds the issue for FDA. Because I think everyone would acknowledge the need to continue research on the possible pathogenicity of simian agents and also the possibility of co-infections and so forth. What we're really trying to establish here is where should we be going as regulators and is this concept of a marker agent itself a matter of concern. I just think the research issue is there, the regulatory question notwithstanding.
ACTING CHAIRMAN ALLEN: All right. Further discussion or questions or we ready to vote?
Dr. Smallwood, would you read the question?
DR. Klein, you look uncomfortable?
DR. KLEIN: I'm still a bit disturbed by this because I absolutely agree with Matt Kuehnert's statement that if we had used this as a marker -- if we had been smart in 1975 to say, you know, a monkey virus is going to jump the species barrier and cause a horrible disease so let's use this as a marker, we would have missed all these other things. It would have been the wrong marker. This is not a high risk group for HIV or HTLV; people in contact with old world and nonhuman primates. So from that standpoint I hate to answer this question yes because I don't think that's the right approach. On the other hand, I clearly am concerned about this agent because we don't know what its pathogenicity is and I think we need to keep an eye on it and other agents like that should they come into to our radar screen as this one has. And that's why I'm hesitate to say no, but I'm real hesitate to say yes because I don't know where that leads.
DR. KUEHNERT: I don't know. I think that it's good that you listed all the questions, because the next question I think leads into that. And I wonder if we can answer question two a certain way and answer question three another way and still be consistent? And it may be because some of us are interpreting the question in a different way. But I feel like I could answer yes to this question and answer no to the next question and be consistent.
DR. HARVATH: I'm wondering if we could maybe maker a comment here about this past year FDA approach NHLBI for cofunding of a workshop in leukocyte reduction for looking at the reduction of various kinds of infectious agents.
And so what I would like to propose for question two is that personally I feel, yes, this is a concern. But what I would like to see is a more open scientific forum in which we take these things on, such as leukocyte reduction. What would be the feasibility of that actually helping us make inroads--it was in the context of, you know, TSE type agents, but let's take SFV as another agent.
I would say yes to question two this does concern me. But I would also like to say let's go forward with some scientific workshops to put more data on the table and look at some of the approaches we could take in hand now, such as leukocyte reduction.
ACTING CHAIRMAN ALLEN: Dr. Strong?
DR. STRONG: Jay's comment about this being a question concerning surrogates, I don't see the word "surrogate" in this question. And I think that if this were in this question, that that might change our answer as well.
ACTING CHAIRMAN ALLEN: Dr. Cunningham-Rundles?
DR. CUNNINGHAM-RUNDLES: I was just saying yes we're concerned. And as Liana was just saying, sure we have concern but in what way does that change what we already said in number one? It doesn't add anything. We already said we're concerned. So number two shouldn't be are we more concerned.
So, I don't see what this is adding to number one currently, unless we add that word "surrogate," which most of us don't think is such a hot idea.
ACTING CHAIRMAN ALLEN: We do have options abstaining or what are the other options? I mean, yes, no or refrain?
DR. TABOR: Jim, I wouldn't agonize over it too much. I think our thinking was in question one was SFV as a risk in itself. Question number two is SFV as a model, not necessarily a surrogate, but a model for what could happen with other viruses. We're certainly getting the benefit of the opinions that are being spoken around the table.
ACTING CHAIRMAN ALLEN: All right. Other questions or comments before we -- yes, Dr. Epstein?
DR. EPSTEIN: Well, just to point out there's the option of tabling the question and just taking any additional comments from the Committee members. Because the discussion is of value in its own right.
DR. STRONG: So moved.
DR. NELSON: I suppose one unknown risk that we've found with other retroviruses is recombination with somebody who is a carrier, let's say, of HTLV-2. And that does something that had the recombination not occurred, it wouldn't have happened. It's not a surrogate, but it's a biologic issue that could be a risk.
On the other hand, there are an awful lot more people who are infected with HTLV-2 than there are Simian Foamy viruses. And I suspect that that will probably continue. But whether or not that could produce a new strain that was more transmissible blood transfusion or otherwise, I don't know.
So it's good not to have a virus with this characteristic, even though you're feeling pretty good at the moment with it.
ACTING CHAIRMAN ALLEN: Dr. Doppelt?
DR. DOPPELT: I would just emphasize a point that was just made a few minutes ago that if you voted yes on number one and you're a hair more concerned about number two, that still doesn't necessarily obligate you to vote yes on number three.
ACTING CHAIRMAN ALLEN: All right. Other comments before Dr. Smallwood?
DR. SCHREIBER: I would like to make a motion that we table this question. As Jay said, that's an option of the Committee.
ACTING CHAIRMAN ALLEN: Yes. I think the best way to do that, given the structure of the Committee, is just to express that, say table the -- abstain or table the question for the time being. Okay.
All right. If we're following Robert's Rules of Orders, I will accept that as an appropriate motion.
DR. LEW: Does someone have to second it? Because I'll second it if that's required.
ACTING CHAIRMAN ALLEN: Yes, it does need to be seconded. Okay.
The motion to table question two is open for discussion. Yes?
DR. DAVIS: Is this just to table question two, or will it also apply to question three?
ACTING CHAIRMAN ALLEN: No. This is just to table question two.
DR. LEW: I think we're all sufficiently a little bit confused what FDA wanted us to address. And I think we've all said our piece, which I hope will be helpful to FDA.
ACTING CHAIRMAN ALLEN: I'm sure it will be looked at very carefully.
DR. QUIROLO: But I would agree with the question as it's written. But the comments that were made outside of the question made me wonder what the question really meant. But I agree that this virus is a great virus to study because it has crossed the barrier like these other simian viruses, and we've only looked at health people. So how many primate handlers have cancer and gotten chemotherapy and then what happened to that virus at that point? We've never looked at that group of people or people that may be immune suppressed when they got a transfusion. So I think there's a long way to go here. But I don't think it should be used as a surrogate marker at this point.
ACTING CHAIRMAN ALLEN: Okay. Are we ready to vote on the motion to table?
I guess our Committee is such that you need to do a formal roll call, is that correct?
DR. SMALLWOOD: That is correct.
Your votes are being recorded in the --
ACTING CHAIRMAN ALLEN: We are voting whether or not to table question two. So a yes, it means yes I vote to table question two. No means I do not. Or you could abstain.
DR. SMALLWOOD: Just for the record, I'm just going to repeat what the Chairman said that the Committee is voting whether on the motion to table voting on question two. Okay. All right.
We're ready for the roll call.
DR. HARVATH: Yes.
DR. SMALLWOOD: Dr. Nelson?
DR. NELSON: Yes.
DR. SMALLWOOD: Dr. Cunningham-Rundles?
DR. CUNNINGHAM-RUNDLES: Yes.
DR. SMALLWOOD: Dr. Kuehnert?
DR. KUEHNERT: Yes.
DR. SMALLWOOD: Dr. Quirolo?
DR. QUIROLO: Yes.
DR. SMALLWOOD: Dr. Hollinger? Dr. Hollinger has left, and he was not privy to this motion.
DR. GOLDSMITH: Abstain.
DR. SMALLWOOD: Dr. Schreiber?
DR. SCHREIBER: Yes.
DR. SMALLWOOD: Dr. Lew?
DR. LEW: Yes.
DR. SMALLWOOD: Dr. Klein?
DR. KLEIN: Yes.
DR. SMALLWOOD: Dr. Doppelt?
DR. DOPPELT: No. I don't like loose ends.
DR. SMALLWOOD: Dr. Davis?
DR. DAVIS: Yes.
DR. SMALLWOOD: Dr. Allen?
ACTING CHAIRMAN ALLEN: No.
DR. SMALLWOOD: And Dr. Strong, our non-voting industry rep, your opinion?
DR. STRONG: Yes.
DR. SMALLWOOD: I thought this was going to be easy. Give me a minute here.
All right. The results of voting to table voting on question two, there were nine yes vote, two no votes, one abstention and the non-voting industry rep agreed with the yes vote.
The results of voting for question number one was a unanimous yes vote.
ACTING CHAIRMAN ALLEN: The motion to table carries.
So a tabled motion can be brought back at any point. This was not a motion that gave a specified time to bring it back. So, Dr. Epstein, we would consider it at some future point if the FDA wishes to bring it back up.
Let's move on to question three.
DR. TABOR: The next slide, please.
Do the available scientific data warrant possible consideration of donor exclusion criteria for exposure to nonhuman primates? Please discuss the factors that should be considered.
ACTING CHAIRMAN ALLEN: This question is open for discussion.
DR. KUEHNERT: Could I just ask a point of clarification first? Is FDA looking for a discussion or looking for a yes/no vote here?
DR. TABOR: I believe both.
ACTING CHAIRMAN ALLEN: Unless the answer were clearly, you know, an unequivocal no, but I think in that instance they would still be very interested in the discussion and considerations. I think that the discussion is going to be important regardless of which way the vote actually goes.
DR. KUEHNERT: Okay.
ACTING CHAIRMAN ALLEN: Dr. Klein?
DR. KLEIN: Well, I think you have to start by saying that any kind of exclusion would have a minimal impact on the blood supply. I don't really think that that's a major issue. So you might say then what's the downside of doing this? And I think there are two major issues that I feel are a downside.
The one is that I can't think of all the questions that could be put on the donor screening form. In fact, I can think of a number of questions, and it's frightening. And I think that if we have enough of those already that may not really protect the recipient of blood transfusion. So I think that's one reason.
The other reason I think it does set a bad precedent. I think it sets the precedent that you could say it's the Crever principle, but I would look at it the other way around: We really have no evidence at all that this a public health threat. So I think it's premature to do so.
That's my discussion. And you'll get my vote later.
ACTING CHAIRMAN ALLEN: Dr. Quirolo?
DR. QUIROLO: I think the wording of exposure would lead to a lot of self-deferral as people wouldn't really know what that meant. So if my neighbor has a monkey, did that mean that I have been exposed to that monkey and I can't donate blood?
ACTING CHAIRMAN ALLEN: Depends on what the monkey threw at you.
DR. QUIROLO: Yes, well or spit at me.
So I think that the way it's worded, besides what Dr. Klein had to say, it's very ambiguous.
DR. TABOR: What we were hoping to get here was your opinion on exclusion criterion in the very broadest sense without trying to narrow it down to any one set of criteria. Just whether we should be considering exclusion criteria. And then if you gave us a yes vote, the second half of it would be for you to clarify where we should go or what pitfalls we should avoid.
ACTING CHAIRMAN ALLEN: Dr. Kuehnert?
DR. KUEHNERT: I mean, I think the concept might be valid.
I mean, first of all, there are things other than donor exclusion criteria which we've talked about today that we might want to sort of emphasize. One is the policy if someone's known to be SFV positive, that they should be told that they should not donate blood or other tissue.
The other is something that was discussed in some conference calls, and I don't know how often this occurs. But having donor drives in places where there might be a high risk population, like having it on zoo grounds or I saw the rate of the donation in a facility in Canada. I wonder was there a donor drive recently in that facility or around that facility. So maybe that's some other things that could be considered besides strictly a donor exclusion criteria.
You know, concerning the criteria, it's all in the details. I think it's very difficult for me to put together any kind of a cohesive set of criteria when you think about the spectrum of possible exposure and given the lack of data we really have. You know given that this can be transmitted through saliva and some of the acrobatics that these nonhuman primates can engage in. And I'm remembering the slide about behavioral observations and even those people could be considered possibly exposed.
So I guess I'm just having difficulty. I mean I'm agreeable to the concept, but I'm having difficulty trying to figure out how you would put that in place practically.
The last thing was about, you know I think we've got a handle on how many people currently could be affected by this sort of exclusion if you ask are you currently A, B or C. But we don't have a good handle on if we ask were you ever exposed in A, B or C. And although I don't think that still would make a huge dent in the donor pool, it would be good to sort of have a better handle on those data.
ACTING CHAIRMAN ALLEN: Dr. Lew and then Dr. Strong.
DR. LEW: Based on what I just heard, it makes sense to me as CDC is recommending potentially wording just if you know that you have the virus, you've been told, you've been tested, that you probably should not donate. Because I think we all agree that if you have this unknown retrovirus, even though we don't know if it's truly pathogenic, there are other models that such as SIV, etcetera, that we need to be concerned about. But that's a very small number of people.
And then beyond that, I can't see having any other questions because we just don't know.
DR. STRONG: We talked this morning about the problems with specificity in the anti-core assay. I can tell you that almost all of our donor questions suffer from a significantly worst specificity problem than our antibody or our antigen assays do.
You know, we can say this might have a very small affect on our donors but every time we add a question, no matter what it is, we lose donors primarily from lack of specificity.
So I also agree. I don't see how we could construct a question. We've been around the block with the xenogeneic transplant questions that one would construct a question that wouldn't cause a lot of lost donors, either from self-deferral or not.
And finally, I think the main thing here is that we don't have any data. And we're supposed to be basing these decisions on science.
ACTING CHAIRMAN ALLEN: Other comments? Okay.
I personally would like to -- I think this has been a helpful discussion even though it's relatively late in the day. I certainly think that Dr. Klein and Dr. Strong have, from a practical blood banking perspective, raised some issues that need to be carefully considered. I will look at it also from a blood donor perspective, and that is that even though we now have the opportunity under selective circumstances, at least for an abbreviated donor questionnaire, that just the total number of questions, the complexity, the amount of information that we're trying to get donors to focus on in a few minutes of time is difficult. And, you know, we need to look at ways to improve the quality of our data collection from donors, quite apart from the issue of the specificity of the questions.
I think we need to continue to address these issues and try to come up with some sort of a resolution. I'm not certain that given the data I've heard today, that I ready to believe that we need to add other questions or make other additions to the process. But we clearly need to continue to evaluate what might be done.
I think earlier Dr. Klein, the last question Dr. Klein certainly raised the issue of the potential for viruses from other animal species and other situations. And I think these are broad based issues that we need to continue to look at very, very seriously.
ACTING CHAIRMAN ALLEN: Dr. Lew?
DR. LEW: If I could just get clarification. Since there's such a small number if people and they're being followed who are known to be positive, is the point mute then because they've already been told please don't donate blood? I'm assuming that you wouldn't need to include -- I mean, that's the only thing is a potential question is that if you've been told you have this virus, I would think it would be very good to make sure that those people don't voluntarily donate.
ACTING CHAIRMAN ALLEN: Yes?
DR. HENEINE: Yes. I think the question is more the infected persons that we have not identified, rather the 15 cases that we have identified. And if you go by the numbers that Dr. Lerche put together, if you have a population of about 100,000 that are exposed, then assume we're seeing a providence of 3.5. Assume it is 1 percent or .3 percent. So you'd be dealing with a substantial number of infected persons that are not recognized. And the average of blood donors among them, say it's like the general population, 5 percent. So it'll be also another substantial number of blood donors that are infected that are donating blood. So that's the issue more than the 15 cases that we've identified that we've counseled them not to donate blood. That is what we're discussing.
So, and even with the 15 cases we have anecdotal information that specificity of the counseling is in question, too. I mean, we had an instance where one case contacted us back and says I would like to donate blood for a paid donation. And then he's checking with this whether this is a good idea or not. So we're not sure if they will all follow the counseling to them, so that's another question.
And since I have the microphone, too, I mean another way to think about the risk, is the other discussions that were brought up, too, regarding xenotransplantation regarding contamination of vaccines. There I think we've kind of draw the line a little bit differently.
And in the case of xenotransplantation we said nonhuman primates are not permissible sources of xenographs.
In the case of vaccines that are grown in simian subcell substrates in primary cells, we screen for foamy virus and we exclude cell substrates that are foamy positive so we don't contaminate the vaccine products with this virus. So here we're drawing a different line and we're saying it's probably okay a contaminated product, but not okay to have a vaccine what is xenographed.
So I guess we have to sort through the risks.
DR. BIANCO: I'm Celso Bianco, America's Blood Centers.
Regarding the comments that Dr. Heneine made, nonhuman primates are also not acceptable as blood donors.
The second thing, Walid, donors -- paid donors are part only to the industry of fractionation of plasma. And that, luckily, is all viral inactivated by processes that we know work very well with retroviruses.
I was struck by the statement that Dr. Kuehnert made a couple of times, but I think it has to be emphasized. If we had done this at the time of HIV, it would not have contributed to anything. That transfer, that jump from the primate to humans of HIV-1, HIV-2, HTLV-1, HTLV-2 probably didn't happen here. It probably, as we know, happened in Africa. And it probably is not the next time going to happen here in one of our primate research facilities or zoos.
I think that we should and must give a lot of attention to these, because that's where the potential for our next epidemic, as a measure to protect the blood supply.
I agree with Dr. Kuehnert that it would have absolutely no impact, except for impact for the donor in terms of creating more complex medical history.
ACTING CHAIRMAN ALLEN: Other discussion among Committee members? Yes, Dr. Goldsmith?
DR. GOLDSMITH: I think we should be vigilant and we should be prudent. And we've seen a path like this before. And I think we have to pay attention to it. So I'd like to weigh in on the more conservative side of this. At least the Committee has heard that as well. That until we know more, maybe we should take the most conservative path.
ACTING CHAIRMAN ALLEN: Do you have a specific recommendation on that or just that's a perspective?
DR. GOLDSMITH: That's a perspective, but you would translate it into an action I think.
DR. KUEHNERT: Let me just say that I would include under donor exclusion criteria not only asking a question of donors, but the other things you know that I mentioned as inclusive in that.
So I just wanted to make that clear that I think it's maybe a boarder definition than what some people might be thinking as far as, you know, putting a question on the donor history questionnaire.
ACTING CHAIRMAN ALLEN: Well, and I certainly think that that is a very appropriate statement and parallels the recommendations that were made in 1983 during the early days of the AIDS epidemic when very clearly we solicited the support of the gay community in cities and communities throughout the country and said please talk with people who you know to be gay and ask them not to donate blood. And that's a first step. And certainly something very analogous as well as broader applications are very much open for consideration. We aren't necessarily talking about something that has to happen in the blood bank itself, blood collection centers, right.
We ready to vote question three?
DR. SMALLWOOD: Question three reads do the available scientific data warrant possible consideration of donor exclusion criteria for exposure to nonhuman primates?
We're ready to vote.
DR. HARVATH: I will have to say the available data do not convince me at this time. What I would like to see is more studies involving with the animal models leukocyte reduction and more research in this area.
DR. SMALLWOOD: Will you be casting a yes or no vote?
DR. HARVATH: That's at this time I would say no.
DR. SMALLWOOD: Thank you.
DR. NELSON: I'd say no. But I would agree that people who are known to be infected with Simian Foamy virus shouldn't donate. But that's a small number of people. But I wouldn't exclude people now based on exposure to nonhuman primates until there was more evidence.
DR. SMALLWOOD: Dr. Cunningham-Rundles?
DR. CUNNINGHAM-RUNDLES: No as well. But I'm assuming that that number is going to grow because I can't imagine that under question number one that people would stop testing animal and nonprimate handlers. And so I expect that number will increase. And so that population will increase.
DR. SMALLWOOD: Dr. Kuehnert?
DR. KUEHNERT: I would say yes using my expanded definition of donor exclusion criteria I talked about before.
DR. SMALLWOOD: Dr. Quirolo?
DR. QUIROLO: No.
DR. SMALLWOOD: Dr. Goldsmith?
DR. GOLDSMITH: Yes.
DR. SMALLWOOD: Dr. Schreiber?
DR. SCHREIBER: I would say no. I think there's just not enough evidence available and we don't even prevalence in the population.
DR. SMALLWOOD: Dr. Lew?
DR. LEW: Can I get clarification of what your expanded definition is? That's not clear to me. What would you say? What is that?
DR. KUEHNERT: Again, I was including under donor exclusion that if someone is known to be SFV positive, they should be deferred. And also, you know, I think this would yet to be defined, but discussions about having donor drives in certain places where there's known to be exposures considered high risk should also be avoided. And that's just my interpretation of this that that is a donor exclusion. So that's why I was supportive of this.
I mean, I feel like this question is very -- you know, warrant possible consideration that it was hard for me to say no. So that's why I said yes.
DR. LEW: My only concern, though, is like not going there to get blood or have donor drives is you're implying those people are, you know, there's something wrong. It's the same thing you had, even though you know you had a bad test, by telling them they can't come back, there's something wrong.
I would say no to this question with the understanding that the people who are infected should not donate.
DR. SMALLWOOD: Dr. Klein?
DR. KLEIN: I don't believe that being in a primate center handling primates represents a risk. I don't believe there's scientific evidence to show that it represents a risk to the blood supply.
My answer is no.
DR. SMALLWOOD: Dr. Doppelt?
DR. DOPPELT: I have no hesitation in voting no.
DR. SMALLWOOD: Dr. Davis?
DR. DAVIS: No.
DR. SMALLWOOD: Dr. Allen?
ACTING CHAIRMAN ALLEN: No, with the caveat that we need to continue to consider the information and collect all information as I know the FDA will do.
DR. SMALLWOOD: And Dr. Strong, your opinion?
DR. STRONG: I like Dr. Doppelt's answer. No.
The results of voting on question number three: Ten no votes, two yes votes and the non-voting industry representative agrees with the no votes.
ACTING CHAIRMAN ALLEN: In question three, the majority is no, there were a lot of qualifications and other discussion.
Dr. Tabor, thank you very much for your presentation.
DR. TABOR: Thank you and the rest of the Committee, and all the speakers.
ACTING CHAIRMAN ALLEN: That concludes our meeting for the day. We reconvene at 8:00 a.m. tomorrow morning.
DR. SMALLWOOD: Correction. 8:30.
ACTING CHAIRMAN ALLEN: 8:30?
DR. SMALLWOOD: 8:30.
ACTING CHAIRMAN ALLEN: Whoa. We get a leisurely breakfast.
DR. SMALLWOOD: Thank you.
ACTING CHAIRMAN ALLEN: All right. Thank you all.
(Whereupon, at 5:26 p.m. the meeting was adjourned, to reconvene tomorrow at 8:30 a.m.)