Despite combination antiretroviral therapy (cART), HIV persists as an integrated provirus in latently infected cells, preventing cure. Recent work in our laboratory suggests that HIV latency in circulating CD4+ T cells is likely due to a series of reversible blocks to HIV transcriptional elongation, distal transcription/polyadenylation, and especially splicing. While existing “latency reversing agents” (LRAs) such as HDACi have been shown to cause modest increases in cell-associated HIV transcripts (including initiated, 5’ elongated, unspliced, and sometimes polyadenylated HIV transcripts) in vivo, they failed to increase multiply-spliced HIV RNA (msRNA), which is a marker of productive infection, in vitro or in vivo. Importantly, these LRAs also failed to induce a reduction in the frequency of latently infected cells in vivo. These results may be explained because HIV expression is also further restricted by inefficient splicing. Thus, there is a critical need to characterize the human cellular factors that regulate the reversible block to HIV multiple splicing and to identify new classes of LRAs that can increase multiply-spliced HIV transcripts. Our main aims are: 1) to elucidate the mechanisms underlying the block to HIV multiple splicing and evaluate new drugs aimed at increasing multiply-spliced HIV RNA and reactivating latency using a well established primary cell latency model; and 2) to evaluate the effect of the novel antiviral drug ABX464, which specifically increases HIV splicing in vitro, on HIV transcription and splicing in vivo in CD4+ T cells from HIV-infected ART-suppressed individuals using samples from a recently-completed clinical trial (ABX464-005; NCT#02990325).