PROJECT SUMMARY/ABSTRACT Although modern antiretroviral (ARV) therapies have dramatically improved the outlooks for people living with HIV, they are unable to cure infection. For people with HIV a cure would represent freedom from many burdens, including stigma, expensive medications, and inflammation-associated co-morbidities. A cure would also have public health benefits, comprising a powerful tool to help end the HIV epidemic. Developing a cure for HIV requires developing an understanding of how the virus persists for years and decades in people, even when new rounds of cellular infection (replication) are blocked by ARVs, and despite the ongoing presence of antiviral immune responses. The dominant paradigm has been that the virus hides in a latent state in infected cells and is thus invisible to immune responses. Efforts to cure infection have therefore focused on therapeutically reversing HIV latency to expose these cells to elimination but have thus far yielded disappointing results. This, along with several converging lines of evidence, have led to more recent hypothesis that hiding from the immune system may not be the only mechanism by which HIV persists – but rather that these rare populations of infected cells may have been selected for those that possess cell-intrinsic resistance to killing by cytotoxic T-lymphocytes, even when they express antigen and are seen. This parallels recent findings from ImmunoOncology where it has now been well established that some immunogenic tumors undergo selection for cell-intrinsic resistance to CTL. For this project, we have assembled a team comprising a pioneer in establishing mechanisms of CTL resistance in tumors, and two HIV experts who have advanced the idea of CTL resistance in this setting through a series of ex vivo studies. By merging these areas of expertise, we Aim to comprehensively describe mechanisms of CTL resistance in HIV-infected primary CD4+ T-cells and to discern which of these are at play in real HIV reservoir cells from people with HIV. We will build from these results to select therapeutic targets and identify combination approaches that integrate these with HIV-specific CTL and latency reversal strategies to achieve specific elimination of HIV reservoir-harboring cells ex vivo. We will also leverage an innovative mouse model to test whether engaging these therapeutic targets limits the seeding of HIV reservoirs in vivo. The results of this project are thus expected to be: i) laying a broad foundation for understanding CTL resistance in the HIV reservoir and ii) pre-clinical validation of multiple therapeutic targets with the potential to contribute to a cure for HIV.