Evaluation Of Antiviral T Cell Responses And T-Scm Cells In Volunteers Enrolled In A Phase I Hiv-1 Subtype C Prophylactic Vaccine Trial In India

T cells play an important role in controlling viral replication during HIV infection. An effective vaccine should, therefore, lead to the induction of a strong and early viral-specific CD8(+) T cell response. While polyfunctional T cell responses are thought to be important contributors to the antiviral response, there is evidence to show that polyfunctional HIV-specific CD8(+) T cells are just a small fraction of the total HIV-specific CD8(+) T cells and may be absent in many individuals who control HIV replication, suggesting that other HIV-1 specific CD8(+) effector T cell subsets may be key players in HIV control. Stem cell-like memory T cells (T-SCM) are a subset of T cells with a long half-life and self-renewal capacity. They serve as key reservoirs for HIV and contribute a significant barrier to HIV eradication. The present study evaluated vaccineinduced antiviral responses and T-SCM cells in volunteers vaccinated with a subtype C prophylactic HIV-1 vaccine candidate administered in a prime-boost regimen. We found that ADVAX DNA prime followed by MVA boost induced significantly more peripheral CD8(+) T-SCM cells and higher levels of CD8(+) T cell-mediated inhibition of replication of different HIV-1 clades as compared to MVA alone and placebo. These findings are novel and provide encouraging evidence to demonstrate the induction of T-SCM and cytotoxic immune responses by a subtype C HIV-1 prophylactic vaccine administered using a prime-boost strategy.