The location, abundance, and proliferation status of SIV-specific CD8 cells in rhesus macaques vaccinated with live attenuated SIVΔnef and challenged with the pathogenic SIVmac251

Abstract

Over 30 million people are infected with HIV/AIDS today. There is an urgent need to develop an effective vaccine. Simian immunodeficiency viruses (SIVs) in rhesus macaques serve as a valuable animal model of HIV infection. Live attenuated SIVs provide protection in SIV infected rhesus macaques challenged with highly pathogenic SIV. The goal of this experiment is to identify correlations of protection that is provided by SIVΔnef vaccination. Here I determined the abundance, location and activation/proliferation status of SIV-specific CD8 T-cells in lymph nodes and spleen from SIVΔnef vaccinated rhesus macaques before and after challenge with the pathogenic SIVmac251. Confocal images were obtained from tissues stained with MHC-tetramers that stain SIVspecific CD8 T cells and Ki67 antibodies that stain proliferating cells and activated T cells. We found similar numbers of SIV-specific CD8 T cells, and similar percentages of SIV-specific CD8 T cells before and after challenge. These results demonstrate that 1) SIV-specific CD8 T cells were present in lymphoid tissues at the time of challenge, and 2) no expansion of SIV-specific CD8 T cells in lymph nodes and spleen was required for protection. This study yields insights into CD8 T cell responses that are likely needed to be induced by a successful HIV vaccine.