RABIES VIRUS-BASED VECTORS AS AN HIV-1 VACCINE

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Highly attenuated rabies virus (RV) vaccine vectors were evaluated for their ability to protect against highly pathogenic SIVmac251 challenge. Mamu-A*01 negative rhesus macaques were immunized in groups of four with either: RV expressing SIVmac239-GagPol, a combination of RV expressing SIVmac239-Env and RV expressing SIVmac239-GagPol, or with empty RV vectors. Eight weeks later animals received a booster immunization with a heterologous RV expressing the same antigens. At 12 weeks post-boost, all animals were challenged intravenously with 100 TCID50 of pathogenic SIVmac251-CX. Immunized macaques in both vaccine groups had 1.31.6-log-fold decrease in viral set point compared to control animals. The GagPol/Env immunized animals also had a significantly lower peak viral load. When compared to control animals following challenge, vaccinated macaques had a more rapid induction of SIVmac251 neutralizing antibodies and of CD8+ T cell responses to various SIV epitopes. Moreover, vaccinated macaques better maintained peripheral memory CD4+ T cells and were able to mount a poly-functional CD8+ T cell response in the mucosa. These findings indicate promise for RV-based vectors and have important implications for the development of an efficacious HIV vaccine.