ABSTRACT - PROJECT 1 Despite antiretroviral treatment (ART) induced viral suppression and gradual decay of the HIV reservoir, PLWH harbor thousands to millions of latently infected CD4+ T cells containing replication competent proviruses, regardless of the duration of ART. Clinical intervention trials aiming to eliminate the HV reservoir have shown that triggering HIV reactivation without boosting innate or adaptive immunity fails to reduce the size of the HIV reservoir. Preliminary data obtained by Dr. Søgaard have shown that priming of specific effector cells, i.e., cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells, enhance their ability to eliminate infected cells, combined with the infusion of broadly neutralizing antibodies (bNAbs) against conserved viral proteins will facilitate clearance of HIV infected cells through FcγR-dependent mechanisms. We and others have shown that gut dysbiosis observed in PLWH modulate the circulating microbiome and metabolome; these impact on successful immune reconstitution post infusion of therapeutic Abs in cancer and HIV infection. In this project we have obtained samples from a clinical trial of 45 virologically suppressed subjects treated with an engager of innate immunity (TLR 9 agonist) and HIV specific bNAbs. We will test the hypothesis that targeting innate immunity will enhance the HIV specific adaptive immune response and as well result in a state of refractoriness to the infection of new target cells upon ATI. We propose three highly integrated and complementary aims. Aim 1 will identify virological features pre-intervention that are associated with delays in viral load rebound and enhanced immune control. In Aim 2, we will identify innate immune antiviral mechanisms triggered by TLR-9 and by Ab/Fc receptor engagement that induce an antiviral immune response that limits viral dissemination and pro- inflammatory immune responses through efficacious adaptive T and B cell responses. Aim 3 will identify the innate immune mechanisms triggered by the microbiome and the metabolome pre-intervention that modulate the immune responses associated control viral during the ATI. Execution of these aims will rely on state-of-the- art assays that measure virological features (i.e., integration sites, translation competence and integrity of viral sequences), immunological and epigenetic features of pro-inflammatory innate immune responses. These in turn are associated with adaptive immune responses that control levels of viral reactivation and time to viral rebound post immune intervention. The data generated will enable us to explore synergies of innate and adaptive immune mechanisms that contribute to virological control and the delay of viral rebound during ATI.