Mamu-B*17 + Rhesus Macaques Vaccinated with env , vif , and nef Manifest Early Control of SIVmac239 Replication

A better understanding of the immune correlates of protection against HIV might facilitate the development of a prophylactic vaccine. Therefore, we investigated simian immunodeficiency virus (SIV) infection outcomes in rhesus macaques expressing the major histocompatibility complex class I alleleMamu-B*17 . Approximately 21% ofMamu-B*17+ macaques spontaneously controlled chronic phase viremia after SIV infection, an effect that may involve CD8+ T cells targeting Mamu-B*17-restricted SIV epitopes. We vaccinatedMamu-B*17+ macaques with genes encoding immunodominant epitopes in Vif and Nef alone (group 1) or together withenv (group 2). Although neither vaccine regimen prevented SIV infection, 5/8 group 2 vaccinees controlled viremia to below detection limits shortly after infection. This outcome, which was not observed in group 1, was associated with vaccine-induced, nonneutralizing Env-binding antibodies. Together, these findings suggest a limited contribution of Vif- and Nef-specific CD8+ T cells for virologic control inMamu-B*17+ macaques and implicate anti-Env antibodies in containment of SIV infection.