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  4. Improving Safety of the Blood Supply from Transmission of HIV/AIDS and Other Emerging Blood Borne Viral and Biodefense Agents by Developing Sensitive Diagnostic Tools and Investigating Disease Pathogenesis
  1. Science & Research (Biologics)

Improving Safety of the Blood Supply from Transmission of HIV/AIDS and Other Emerging Blood Borne Viral and Biodefense Agents by Developing Sensitive Diagnostic Tools and Investigating Disease Pathogenesis

Principal Investigator: Indira Hewlett, PhD
Office / Division / Lab: OBRR / DETTD / LMV

General Overview

HIV diagnostics and pathogenesis

HIV/AIDS is a global public health concern, with 33 million infections worldwide and several million deaths a year.

The virus is very diverse and new strains continue to emerge and spread rapidly worldwide. This poses challenges to diagnosing infected individuals and developing new vaccines and therapies. Therefore, it is imperative that FDA determine if newly developed tests for screening the blood supply for HIV accurately detect all the existing and emerging strains of the virus in blood samples. Our ongoing studies in Africa will help FDA in its global collaborations aimed at ensuring there are accurate HIV diagnostic tests and safe and effective vaccines available to respond to the changing population of AIDS viruses.

Our laboratory studies the factors that cause variations in the response of humans to HIV diversity. These studies will provide new insights that will support development of improved diagnosis, disease monitoring, drug design, and vaccines. We also helped to produce a new FDA document that offers guidance to blood donor facilities in identifying donors at increased risk for being infected with the variety of HIV-1 called "group O." This will help to screen out donors who might be infected based on having spent time in certain parts of Africa or having received blood transfusions or engaged in sexual activity with residents or former residents in those areas.

Novel detection technologies

Although testing for HIV has reduced the risk of transmitting the virus through donated blood, there are still three challenges to keeping the blood supply safe: 1) existing tests are performed only on plasma, while many agents are found mostly in blood cells; 2) testing requires large volumes and labor intensive instrumentation; and 3) existing tests cannot readily be modified to detect simultaneously the increasing number of infectious agents that pose new threats to the blood supply.

The goals of our work are to 1) develop new, improved diagnostic tools for testing blood and plasma and rapidly detecting emerging pathogens that threaten public health; and 2) provide FDA product reviewers with improved scientific understanding of novel technologies that might be applied by manufacturers, enhancing the review and evaluation of new diagnostic tests for blood-borne pathogens and bioterrorism agents.

Pandemic influenza and blood safety

Each year the FDA helps industry and international health agencies choose which influenza viruses will be represented by that year's "flu shot." FDA research also contributes to tests that determine the safety and potency of the vaccine. In addition to seasonal influenza there are other types of influenza of concern to FDA and other public health agencies.

H5N1 strains of avian influenza (bird flu) infect humans with a mortality rate close to 50%, much higher than the rate for seasonal influenza. Researchers have detected H5N1 in the blood of severely ill persons using very sensitive methods that can identify the genetic material of these pathogens. In 2009 another influenza virus called "swine flu" or H1N1, caused several hundred deaths in the US and spread quickly throughout the world.

Our group is developing assays as part of influenza pandemic preparedness. In collaboration with the FDA's Center for Devices and Radiological Health we are studying how the disease progresses, and how that progression is linked to the level of influenza viruses in the blood or nasal secretions. The major goal of this study is to determine whether influenza virus is present in blood in the asymptomatic phase, that is, when the infected individual is not showing evidence of disease. These data would help regulatory and public health officials to develop a blood screening policy that addresses donor deferral and product shortage issues during a pandemic if the virus is detected in the the blood of potential donors during the pre-symptomatic phase. In addition we are studying the correlation of the levels of flu virus genetic material with the ability of the virus to infect humans using animals as models of this infection. The laboratory also contributed significantly to developing a document that provides industry with guidance and recommendations for the assessment of donor suitability and blood product safety with regard to pandemic influenza

XMRV and blood safety

In 2006, the human retrovirus XMRV (xenotropic murine leukemia virus-related virus) was identified and reported to be associated with certain cases of prostate cancer and, more recently, scientists have shown an association with chronic fatigue syndrome (CFS). XMRV has also been found in about 4% of healthy individuals.

The results of various studies suggest that people infected with XMRV carry the virus in their blood stream. This raises public health concerns that such individuals could spread the virus through blood donations. Therefore, our laboratory is developing sensitive ways to test for XMRV in blood and to test the accuracy of assays used by different laboratories to diagnose infection with XMRV. This work will help to prepare blood collection centers for testing blood for this virus in the event that it becomes necessary in order to ensure the safety of the blood supply.

These tools will also help public health officials and researchers to collect data on the prevalence and distribution of XMRV and to study infection and transmission of the virus.

Therefore, we plan to develop in-house tests to detect the virus, the immune response to the virus, and its genetic material. Our laboratory also hopes to study the prevalence of XMRV in other parts of the world, such as Cameroon in African, where similar types of viral infections are known to be prevalent. We also plan to investigate the ability of the virus to infect hematopoietic cells, which are the parent cells that give rise to the various blood cells.

Scientific Overview


We obtained plasma and viruses representing major new strains from Cameroon, where all diverse HIV strains are prevalent and new strains continue to emerge. Our laboratory uses these samples to evaluate new antibody/antigen and nucleic acid tests (NAT) designed to detect and quantify these strains. We use gene sequencing to identify strains, tropism, and drug resistance. Correlation of sequencing data with cell-based phenotyping for tropism will provide FDA with valuable experience with this emerging class of products. The laboratory now plans to use new, high throughput, ultra-deep sequencing techniques to characterize virus genetic material.

Although most samples were detected by FDA licensed assays, NAT assays only inconsistently detected some CRF02_AG and CRF01_AE specimens. Therefore, we tested these strains in a collaborative study. New reference panels of these viruses were prepared to help FDA evaluate licensed and new NAT assays to detect them.

Our laboratory is also using in vitro cell culture systems and molecular genomics to study the impact of strain diversity, sex hormone effects, host genetics and cell signaling pathways on viral pathogenesis.

Novel detection technologies

We use nanoparticles in ELISA rapid or microarray formats as proof-of-concept strategies to improve assays. Gold nanoparticles coupled with silver enhanced detection of HIV-1 p24 antigen by approximately 100-150-fold compared to the conventional ELISA format. Fluorescent europium (Eu+) nanoparticles (NP) reduced assay time while achieving similar levels of sensitivity. Europium nanoparticles also enhanced detection of anthrax 50-100 fold, allowing earlier detection of the toxin than was previously possible. We showed that nanoparticles offer remarkable improvements in the sensitivity of protein-based assays for pathogens and might provide improved diagnostic tools for pathogens in the future.

Our laboratory is also evaluating non-PCR nanoparticle-based genomic microarray NAT techniques that achieve PCR-like detection limits without using enzymes or PCR amplification. West Nile Virus (WNV) RNA detection was comparable to PCR using these arrays. We detected Ebola, Marburg and Lassa viruses with a high degree of sensitivity using this approach and successfully used it for multiplexed detection and genotyping of major influenza viruses, including H1N1, H3N2 and H5N1. The signals in this assay could be visually read by enhancement with silver staining allowing adaptation to rapid detection formats. Our work clearly demonstrates the potential for nanotechnology to provide new, rapid and sensitive diagnostics for pathogens.

Pandemic influenza and blood safety

We determined the presence of virus in the blood of ferrets and mice infected with different doses of H5N1 virus, collecting blood, lungs, nasal washes, nasal turbinates and brain at different time points. Sensitive taqMan and virus culture assays are being used to measure virus in blood and the various tissues. We are planning to inoculate H5N1 and 2009 H1N1 intravenously into ferrets and mice to determine transmissibility and pathogenesis of virus if transmitted through the intravenous route, simulating transfusion.

Our preliminary findings indicate that viremia in H5N1 infection can be detected at the onset of symptoms and is generally associated with fatal outcomes in ferrets. Similar studies are underway with H1N1 infection. In a separate study we tested plasma from 300 blood donors using sensitive Taqman assays for H1N1 and have so far found no positive samples in this sample set. These findings are important in our understanding of influenza viremia and its detectability in blood donors.

XMRV and blood safety

In 2006, the human retrovirus XMRV (xenotropic murine leukemia virus-related virus) was identified and reported to be associated with certain cases of prostate cancer and, more recently, with chronic fatigue syndrome (CFS). XMRV has also been found in about 4% of healthy individuals.

Studies have shown that XMRV infects T and B cells, and transient viremia has been detected in animals after infection with XMRV. In addition, virus from plasma was able to infect susceptible cells, suggesting that infectious virus is present in the blood stream. This raises public health concerns about the safety of the blood supply. It is therefore critical to develop sensitive test methods and well-characterized reference reagents to standardize assays from different labs and ensure the accuracy of diagnostic findings. The reference panels will be used for lot release testing of kits in the event testing of the blood supply becomes necessary. These tools will also be needed to perform studies of prevalence, distribution, virus infectivity, and transmission, to clarify and corroborate the findings of XMRV that have been reported so far. Current data on prevalence in the general population is primarily derived from a restricted geographic locations in the US; additional studies are needed to examine prevalence on other populations.

Patient-derived XMRV has been shown to be infectious, and both cell-associated and cell-free transmission of the virus is possible, and a study in rhesus macaques indicated a viremic phase. These findings point to a new transfusion threat that needs further investigation.

Therefore, we proposed to 1) develop in-house Taqman, antigen and antibody assays to detect the virus and its immune responses; 2) develop reference panels for detection of nucleic acid, and antibody, 3) study prevalence in other settings including Cameroon in Africa where other retroviral infections are known to be prevalent; and 4) investigate infectivity and tropism of the virus for hematopoietic cells in cell culture systems and appropriate animal models.

We have developed sensitive Taqman assays based on primers from the gag region to make it specific for XMRV. In addition, we are obtaining infectious clones, virus isolates, recombinant proteins, and antibodies for further characterization in a collaborative study based on sequence analysis and evaluation of reactivity using tests developed at CBER and other laboratories in a collaborative study.

For the nucleic acid test (NAT) panel, we provided laboratories with virus preparations diluted in plasma for testing. Results of all labs will be evaluated statistically to obtain a consensus value. For antibody panels, reactivity of candidate materials will be tested in multiple laboratories to determine the suitability of the material for use as a reference reagent. The assays will be used to test samples previously obtained from donors in Cameroon for the presence of XMRV sequences by NAT or antibodies by ELISA. Various T and B cell lines, monocytes, and PBMCs will be infected with different concentrations of the virus to evaluate infectivity. Transmissibility of cell-free and cell-associated virus between lymphoid cells and indicator cells will be studied. Rhesus macaque studies will be performed to study the natural history of the virus and secondary transmission through transfusion. Samples collected at various time points after infection can also serve as useful reagents to assess the sensitivity of assays and as future reference reagents.

The proposed studies are expected to provide the following outcomes: 1) optimizing in-house assays for studies of XMRV prevalence, transmission, and pathogenesis; 2) developing reference reagents for standardization of XMRV assays based on NAT or antibody and animal derived seroconversion panels for sensitivity evaluation; 3) identifying seroprevalence in persons from different geographic regions; 4) gaining new knowledge of cell tropism, transmissibility, and infectivity for blood cells using in vitro cell culture systems; and 5) evaluating infectivity, transmissibility, and pathogenesis of the virus using susceptible animal models.


  1. Pathogens 2022 Jul 8;11(7):778
    Visible 405 nm violet-blue light successfully inactivates HIV-1 in human plasma.
    Ragupathy V, Haleyurgirisetty M, Dahiya N, Stewart C, Anderson J, MacGregor S, Maclean M, Hewlett I, Atreya C
  2. Microbes Infect 2022 Apr-May;24(3):104912
    Components of apoptotic pathways modulate HIV-1 latency in Jurkat cells.
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  3. Viruses 2022 Jan 6;14(1):95
    Modulation of HIV replication in monocyte-derived macrophages (MDM) by host antiviral factors secretory leukocyte protease inhibitor and Serpin family C member 1 induced by steroid hormones.
    Biswas S, Chen E, Gao Y, Lee S, Hewlett I, Devadas K
  4. Viruses 2021 Jul 20;13(7):1417
    Identification, genetic characterization and validation of highly diverse HIV-1 viruses for reference panel development.
    Zhao J, Huang H, Lee S, Ragupathy V, Biswas S, Mbondji-Wonje C, Wang X, Jiang A, Hewlett I
  5. Biores Open Access 2020 Nov 24;9(1):243-6
    Biotin interference in point of care HIV immunoassay.
    Haleyur Giri Setty MK, Lee S, Lathrop J, Hewlett IK
  6. Int J Mol Sci 2020 Sep 22;21(18):E6970
    Comparison of miRNA expression profiles between HIV-1 and HIV-2 infected monocyte-derived macrophages (MDMs) and peripheral blood mononuclear cells (PBMCs).
    Biswas S, Chen E, Haleyurgirisetty M, Lee S, Hewlett I, Devadas K
  7. Health Sci Rep 2020 Aug 24;3(3):e182
    Detection of highly divergent HIV-1 in clinical specimens using rapid HIV serologic assays.
    Mbondji-Wonje C, Lee S, Hewlett I
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    Genetic variability of the U5 and downstream sequence of major HIV-1 subtypes and circulating recombinant forms.
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    The effects of MAPK p38alpha on AZT resistance against reactivating HIV-1 replication in ACH2 cells.
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    Exploring the immunomodulatory role of depot medroxyprogesterones acetate and endogenous progesterone levels in HIV infected and uninfected women.
    Mnqonywa N, Abbai N, Ragupathy V, Ramjee G, Hewlett I, Moodley D
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    Development and validation of plasma miRNA biomarker signature panel for the detection of early HIV-1 infection.
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    Streptavidin-conjugated gold nanoclusters as ultrasensitive fluorescent sensors for early diagnosis of HIV infection.
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    Application of nanotechnology in biosensors for enhancing pathogen detection.
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    Comparison of detection limits of 4th generation combination HIV antigen/antibody, p24 antigen and viral load assays on diverse HIV isolates.
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    PTAP motif duplication in the p6 Gag protein confers a replication advantage on HIV-1 subtype C.
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    Distinctive variation in the U3R region of the 5' long terminal repeat from diverse HIV-1 strains.
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    Differentially expressed host long intergenic noncoding RNA and mRNA in HIV-1 and HIV-2 infection.
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    Modulation of HIV replication in monocyte derived macrophages (MDM) by steroid hormones.
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    Femtogram level sensitivity achieved by surface engineered silica nanoparticles in the early detection of HIV infection.
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    Differences in activation of HIV-1 replication by superinfection with HIV-1 and HIV-2 in U1 cells.
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    Comparative performance evaluation of carbon dot-based paper immunoassay on Whatman filter paper and nitrocellulose paper in the detection of HIV infection.
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    Identification of host micro RNAs that differentiate HIV-1 and HIV-2 infection using genome expression profiling techniques.
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    Development of a candidate reference material for adventitious virus detection in vaccine and biologicals manufacturing by deep sequencing.
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    Analysis of host gene expression profile in HIV-1 and HIV-2 infected T-cells.
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    Identification and characterization of a highly pathogenic H5N1 avian influenza A virus during an outbreak in vaccinated chickens in Egypt.
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    Non-invasive optical sensor based approaches for monitoring virus culture to minimize BSL3 laboratory entry.
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    Nanomicroarray and multiplex next-generation sequencing for simultaneous identification and characterization of influenza viruses.
    Zhao J, Ragupathy V, Liu J, Wang X, Vemula SV, El Mubarak HS, Ye Z, Landry ML, Hewlett I
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    HIV-1 induced nuclear factor I-B (NF-IB) expression negatively regulates HIV-1 replication through interaction with the long terminal repeat region.
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