Latency reversal agents affect differently the latent reservoir present in distinct CD4+ T subpopulations

CD4+ T cell; HIV-1; Latent reservoirCélula T CD4 +; VIH-1; Reservorio latenteCèl·lula T CD4 +; VIH-1; Reservori latentLatency reversal agents (LRAs) have proven to induce HIV-1 transcription in vivo but are ineffective at decreasing the size of the latent reservoir in antiretroviral treated patients. The capacity of the LRAs to perturb the viral reservoir present in distinct subpopulations of cells is currently unknown. Here, using a new RNA FISH/flow ex vivo viral reactivation assay, we performed a comprehensive assessment of the viral reactivation capacity of different families of LRAs, and their combinations, in different CD4+ T cell subsets. We observed that a median of 16.28% of the whole HIV-reservoir induced HIV-1 transcripts after viral reactivation, but only 10.10% of these HIV-1 RNA+ cells produced the viral protein p24. Moreover, none of the LRAs were powerful enough to reactivate HIV-1 transcription in all CD4+ T cell subpopulations. For instance, the combination of Romidepsin and Ingenol was identified as the best combination of drugs at increasing the proportion of HIV-1 RNA+ cells, in most, but not all, CD4+ T cell subsets. Importantly, memory stem cells were identified as highly resistant to HIV-1 reactivation, and only the combination of Panobinostat and Bryostatin-1 significantly increased the number of cells transcribing HIV within this subset. Overall, our results validate the use of the RNA FISH/flow technique to assess the potency of LRAs among different CD4+ T cell subsets, manifest the intrinsic differences between cells that encompass the latent HIV reservoir, and highlight the difficulty to significantly impact the latent infection with the currently available drugs. Thus, our results have important implications for the rational design of therapies aimed at reversing HIV latency from diverse cellular reservoirs.This study was supported by the American National Institutes of Health (grant R21AI118411 to MJB), the Spanish Secretariat of Science and Innovation and FEDER funds (grant SAF2015-67334-R [MINECO/FEDER]), a unrestricted research grant from Bristol-Myers Squibb S.A.U (PfC-2015 AI424-564) to MJB, the Spanish "Ministerio de Economia y Competitividad, Instituto de Salud Carlos III"(ISCIII, PI17/01470) to M.G, a research grant from Gilead Sciences (GLD17-00204) to M. B, GeSIDA and the Spanish AIDS network "Red Tematica Cooperativa de Investigacion en SIDA" (RD16/0025/0007) to ER. The Miguel Servet program funded by the Spanish Health Institute Carlos III (CP17/00179) to MJB. The "Pla estrategic de recerca i innovacioen salut" (PERIS), from the Catalan Government to MG