Global HIV Vaccine Development
The Vaccine Research Center (VRC) has developed a prime-boost strategy using a multiclade DNA plasmid vaccine for prime vaccination and a recombinant adenoviral vector vaccine (rAd5) for booster vaccination. This product concept has been evaluated in Phase I and Phase II studies in over 1000 subjects in collaboration with three clinical network partners in both domestic and international settings. These include the NIAID HIV Vaccine Trials Network (HVTN), the US Military HIV Research Program (USMHRP), and the International AIDS Vaccine Initiative (IAVI). HVTN has study sites in the United States, South Africa, Jamaica, Haiti, and Brazil; USMHRP has study sites in Kenya, Uganda, and Tanzania; and IAVI has study sites in Rwanda and Kenya.
These studies have culminated in plans to do a test-of-concept Phase II efficacy study that will be conducted in North America with the HVTN. The HVTN 505 study is proposed to begin in 2009 and will be designed to test whether the VRC candidate DNA/rAd5 prime-boost vaccination regimen can reduce viral load in subjects who become infected despite vaccination. Viral load is being tested as a surrogate marker for disease progression along with other clinical and virological endpoints, and will be analyzed together with immune response data to identify potential correlates of protection. Immune assays for the Phase II studies will be performed at NVITAL and in the HVTN core laboratories, both NIAID-supported immune assay programs.
In parallel with the test-of-concept study to determine whether vaccine-induced T cell responses can provide efficacy, preclinical discovery work is proceeding on structure-based design of new immunogens to induce broadly neutralizing antibody. In addition, new antigen designs and alternative gene-based vectors are being developed to improve vaccine-induced T cell responses, and alternative delivery approaches are being explored to induce better mucosal immunity.
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