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U.S. Department of Health and Human Services

Vaccines, Blood & Biologics

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Studies on a Potential Vaccine for the Treatment of HIV Infection and Sensitive Immunoassays to Simultaneously Detect Multiple Infections and Monitor Post-vaccination Safety

Principal Investigator: Subhash Dhawan, PhD
Office / Division / Lab: OBRR / DETTD / LMV


General Overview

Human immunodeficiency virus type-1 (HIV-1) causes AIDS, a disease that infects and kills certain immune system cells. The various symptoms of AIDS are due primarily to the ability of HIV to incapacitate the immune system.

The HIV protein called "Tat" is essential for the ability of the virus's genes to force infected cells to produce new copies of the virus. In this way, Tat plays a key role in the progression of HIV-1 infection.

The ability of Tat to regulate genes in the cells it infects makes this protein a potential target for a therapeutic vaccine. Therapeutic vaccines do not prevent disease; they are designed to treat a person who already has the disease.

Our research focuses on developing new therapies to reduce the progression of HIV infection, especially when conventional treatments fail to stimulate an effective immune response to the virus. This immune system failure can occur in two ways: 1) when varieties of HIV are already resistant to treatment; and 2) when mutations in the genetic makeup of HIV cause sensitive varieties of the virus to mutate and become resistant to AIDS drugs.

Over the past 20 years, researchers have learned a great deal about the molecular mechanisms that control HIV replication. However there has been little success in developing either an effective therapeutic vaccine to control HIV disease or tools to monitor the safety of such a vaccine after it is administered.

The goals of our research program are to 1) increase our understanding of how Tat regulates HIV replication; 2) evaluate the potential use of Tat as a therapeutic vaccine; and 3) develop simple yet highly sensitive tests that detect a variety of different infections transmitted by blood transfusions.

FDA evaluates the design and manufacturing of vaccines and other biologics to ensure that these products are safe and effective. This task includes chemical analyses of the products that enable Agency reviewers to fully understand their biochemical makeup.

Our research is important because it provides new knowledge that will enable FDA reviewers to evaluate the performance of diagnostic tests for existing and emerging pathogens, to determine post-vaccination safety, and to monitor how patients respond to drug therapy. Therefore, these studies have significant potential for improving public health.

The studies directly support FDA efforts to establish policies for the manufacture and use of certain biological products, to provide updated recommendations for the approval of vaccines, blood products, other biologic therapeutics, and to develop simple and economical, yet highly sensitive, laboratory-based tests to monitor the safety and effectiveness of these products.


Scientific Overview

Frequent travels to endemic disease areas and changing climate conditions continue to offer significant opportunities for the spread of deadly infections.

The public health threats associated with existing and emerging transfusion-transmitted infections warrant the development of simple diagnostic tests that can accurately and simultaneously detect multiple analytes in a single specimen.

Immunoassays and nucleic acid tests provide versatile tools for detecting analytes in biological fluids. These highly effective analytical techniques have been successfully used in a wide range of disciplines, such as monitoring antibody responses to vaccination, measuring viral load during drug therapy, and diagnosing various infections in clinical laboratories.

Emerging infectious diseases pose great threat to public health, including recipients of blood transfusions. Among many blood-borne emerging infections transmitted through transfusion of infected blood donated by apparently healthy and asymptomatic blood donors are dengue, malaria, variant CJD, and West Nile viruses (WNV). Dengue virus (DV) and WNV belong to the family of flaviviruses that can be transmitted to humans by mosquitoes and other non-human carriers, as well as by transfusion of blood or blood products, bone marrow, organ transplant, hemodialysis, and exposure to infected mucous membranes. The presence of these infectious agents in the blood supply could significantly impact the safety of blood and blood-derived biologics, especially in the case of treatments for hemophilia.

We have designed a quantitative RT-PCR (qRT-PCR) assay to detect HIV-1, dengue, and West Nile viruses with nucleotide sequences that are highly specific for each of these pathogens and with no cross-reactivity. The qRT-PCR can provide results with a much greater sensitivity than standard PCR and can quantify pathogens in the early phase of infection. This technique is also suitable for identifying candidate pathogens for effective anti-viral therapy.

Our laboratory has also shown that the induction of heme oxygenase-1 (HO-1), an endogenous cell host factor, substantially inhibited infection of cells with HIV and other pathogens. The mechanism of action of HO-1 induction as a host defense factor is not clear. However, these preliminary results are highly encouraging, since they demonstrate activation of a natural host defense mechanism against these individual pathogens, as well as against multiple co-infections.

Currently, there are no vaccines for the prevention of WNV or DV infections and no effective drugs to treat these blood-borne diseases. Therefore, HO-1 induction might provide a useful strategy for minimizing emerging public health crises and maximizing economical therapeutic interventions.


Publications

J Leukoc Biol 2010 May;87(5):915-24
Lipopolysaccharide suppresses HIV-1 replication in human monocytes by protein kinase C-dependent heme oxygenase-1 induction. Exit Disclaimer
Devadas K, Hewlett IK, Dhawan S

Peptides 2007 Mar;28(3):496-504
Antibodies against a multiple-peptide conjugate comprising chemically modified human immunodeficiency virus type-1 functional Tat peptides inhibit infection. Exit Disclaimer
Devadas K, Boykins RA, Hewlett IK, Wood OL, Clouse KA, Yamada KM, Dhawan S

Expert Rev Mol Diagn 2006 Sep;6(5):749-760
Signal amplification systems in immunoassays: implications for clinical diagnostics. Exit Disclaimer
Dhawan S

Peptides 2006 Apr;27(4):611-21
Selective side-chain modification of cysteine and arginine residues blocks pathogenic activity of HIV-1-Tat functional peptides. Exit Disclaimer
Devadas K, Boykins RA, Hardegen NJ, Philp D, Kleinman HK, Osa EO, Wang J, Clouse KA, Wahl LM, Hewlett IK, Rappaport J, Yamada KM, Dhawan S

J Immunol 2006 Apr 1;176(7):4252-7
Hemin Activation Ameliorates HIV-1 Infection via Heme Oxygenase-1 Induction. Exit Disclaimer
Devadas K, Dhawan S

J Immunol 2004 Dec 1;173(11):6735-44
Mechanisms for Macrophage-Mediated HIV-1 Induction. Exit Disclaimer
Devadas K, Hardegen NJ, Wahl LM, Hewlett IK, Clouse KA, Yamada KM, Dhawan S

 

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