Infrequent, low magnitude HIV-specific T cell responses in HIV-uninfected participants in the 1% tenofovir microbicide gel trial (CAPRISA004)

Macaque studies of antiretroviral-containing microbicide gels administered rectally or vaginally followed by SIV challenge have documented priming of SIV-specific T cell responses in the blood of protected animals. This concept has been termed “chemo-vaccination”, where aborted viral replication is thought to leave an immune footprint of exposure, which may augment protection provided by microbicides/PrEP. We investigated whether T cell responses were detectable in women participating in CAPRISA004 1% tenofovir microbicide trial, which showed 39% efficacy in reducing HIV acquisition.