SUMMARY HIV assaults deep tissues including the gastrointestinal (GI) and genitourinary (GU) tract within days after transmission to a new person. It then quickly and irreversibly changes the local immune environment and establishes a reservoir in resident cells. Our current understanding of the different mechanisms that allow HIV persistence in GI, GU, and adipose tissues and of how the local immune environment impacts HIV reservoir persistence and dynamics remains superficial, however. The rationale for this project is that understanding these processes will be important for HIV cure efforts, which have until recently largely ignored non-blood reservoirs, and to improve the health of persons with HIV (PWH) as they age. In response to RFA DK-20-023, we built a team led by Drs. Smith and Rivera-Nieves (Co-PIs with complementary expertise in virology, gastroenterology and mucosal immunology) with the objective to precisely define the contributions of various viral and host mechanisms of HIV reservoir renewal and persistence across NIDDK targeted tissues and blood, using the novel Last Gift rapid autopsy cohort. Our overall hypothesis is that HIV reservoirs persist in NIDDK targeted tissues and are differentially renewed by various cellular and viral mechanisms. To address these open questions, our study will collect and analyze NIDDK targeted tissues throughout the human GI and GU tracts and intra-abdominal and subcutaneous adipose tissue of altruistic PWH enrolled in the Last Gift cohort, an ongoing rapid autopsy study. Immune cells collected from these individuals before death will also be analyzed, in parallel, in order to facilitate comparison with prior work. Some participants (n=15) will remain virally suppressed until the time of death, while others (n=5) will choose to stop their antiretroviral (ARV) treatment before death. The proposed research is innovative because we propose to map HIV burden and activity in tissues with different immune and ARV environments (Aim 1), to determine the role of clonal expansion as a driver of HIV persistence during treatment and viral rebound after treatment interruption (Aim 2) and to develop an integrative/innovative phylogeographic Bayesian approach to jointly analyze virological and immunological data to unravel viral dispersal and reseeding across the body in relation to local environments. By analyzing these connections, we expect to reveal pathways and interactions that may differentially impact HIV associated inflammation. We believe our proposed study to be significant because this is a unique opportunity to provide new insights into the mechanisms of HIV persistence. Such findings would be important for the development of strategies aimed to thwart local HIV-associated inflammation, which is associated with HIV pathogenesis in the gut, genital tract and adipose tissues.