Successful development of a vaccine against HIV will likely require the induction of both antibody and/or cellular immune responses sufficient to prevent infection or disease respectively following infectious challenge. While the induction of antibody responses for a variety of other infectious pathogens is readily achieved by a variety of vaccine formulations, live attenuated, recombinant viral vaccines or plasmid DNA vaccines only induce the induction of long-lived cellular immune responses, particularly CD8+ T cell responses. Moreover, since live attenuated HIV vaccines might be precluded from use due to safety concerns and DNA vaccines at present only induce modest CD8+ T cell responses in humans, there is an urgent need to develop ways to enhance the generation and maintenance of CD8+ T cell responses in humans in following immunization. This study focuses on how to optimize the magnitude and duration of CD8+ T cell responses following vaccination in rodents and primates using a variety of vaccine formulations. The data obtained over this past year have shown the following; 1. A comparative analysis of single or combination TLR ligands was done in NHP using SIV Gag protein and an oil/water emulsion. Amongst the adjuvants used, Poly IC and a TLR 7/8 agonist were the most potent for inducing SIV Gag specific CD4 and CD8+ T cell responses. 2. A comparative analysis of adjuvants and formulation was recently completed in NHP using HIV Env protein. This study focused on two clinically approved adjuvants ( alum and MF-59) with or without TLR 4 or TLR 7 ligands as additional immune stimulators. The data generated so far show that MF-59 induces more potent humoral and cellular immunity than alum when given with HIV Env protein. Combining alum with a TLR 7 ligand strongly enhanced immunity compared to alum alone. By contrast, adding TLR 4 or TLR 7 ligands to MF 59 did increase immunity compared to alum alone. In terms of T cell immunity, MF 59 induced a mixed Th1 and Th2 cytokine response. More recent analysis has been done to determine the extent of affinity maturation of the HIV Env B cell response using deep sequencing. 4. A comparative analysis of adenoviral or pox viral vectors encoding SIV Gag was initiated this year. The data show that the amount and duration of antigen has a dramatic influence on the strong CD8+ T cell immunity with rAd5 compared to other Ad serotypes. By contrast, there is minimal innate immunity induced by Ad5. The current work focuses on the mechanisms by which innate immune controls antigen expression in antigen presenting cells and determining how specific innate pathways enhance or inhibit the CD8+ T cell response.

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