Characterization of HIV multiple splicing stage aiming to efficiently reverse HIV latency
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).