ABSTRACT The key obstacle to cure HIV infection is a reservoir of latently-infected memory CD4+ T cells that persist despite long-term ART and is maintained though cellular proliferation. This latent reservoir involves a heterogeneous population of memory CD4+ T cell subsets at various differentiation stages. Each subset displays a distinct proliferative capacity, HIV transcriptional activity, and viral inducibility. Cells presenting a differentiated phenotype account for the majority of clonal expansions in the reservoir. However, such expended clones often wax and wane and the core of HIV reservoir likely lies in multipotent memory CD4+ T cells with high survival and self-renewal abilities such as central (CM) and stem cell memory (SCM) CD4+ T cells. The Wnt/β-catenin signaling pathway regulates the balance between self-renewal and differentiation of these long-lived memory CD4+ T cells. We recently showed that inhibition of the interaction of β-catenin with the transcriptional coactivator CPB decreased the proliferation of SCM and CM CD4+ T cells and modified their transcriptome towards a more differentiated phenotype in ART-suppressed SIV-infected rhesus macaques (RMs). The Wnt/β-catenin signaling pathway has also been implicated in HIV replication suppression with a potential role of CD8+ T cell secretion of Wnt ligands. The objective of this application is to investigate this dual role of the Wnt/β-catenin signaling pathway on HIV persistence with the central hypothesis that pharmacological targeting of two critical steps of the Wnt/β-catenin pathway can alter HIV reservoir maintenance by (i) interfering with the self-renewal ability of SCM and CM CD4+ T cells, and (ii) alleviating HIV transcriptional repression. Using the highly relevant model of SIV-infected ART-treated RMs, we will address this hypothesis in three Specific Aims. In Aim 1, we will characterize the impact of the pharmacological modulation of β-catenin-mediated transcription on memory CD4+ T cell dynamics and SIV reservoir composition. In Aim 2, we will assess if the transient induction of long-lived memory CD4+ T cell differentiation potentiate the activity of a latency reversing agent. In Aim 3, we will explore the effect of Wnt ligand secretion blockade on long-lived memory CD4+ T cell self-renewal and SIV latency. The proposed experiments build upon an appreciation of the immunologic complexity of CD4+ T cell reservoir dynamics. This conceptually innovative work will provide critical new information on the biology of HIV persistence in memory CD4+ T cells.