UC Berkeley

Complete eradication of HIV-1 infection is impeded by the existence of cells that harbor chromosomally integrated but transcriptionally inactive provirus. These latently-infected cells can persist for years without producing viral progeny, rendering them refractory to immune surveillance and antiretroviral therapy and providing a permanent reservoir for the stochastic reactivation and reseeding of HIV-1. Strategies for purging this latent reservoir are thus needed to eradicate infection. Here we show that engineered transcriptional activation systems based on CRISPR/Cas9 can be harnessed to activate HIV-1 expression in cell line models of latency. We utilized two distinct CRISPR transcriptional activation systems, dCas9-VP64 and the synergistic activation mediator (SAM) complex, to target numerous sites across the HIV-1 long terminal repeat (LTR) promoter and observed robust expression from the full-length HIV-1 promoter in multiple cell line models of HIV-1 latency. We further demonstrated that complementing Cas9 activators with latency-reversing compounds can enhance latent HIV-1 transcription and that epigenome modulation using CRISPR-based acetyltransferases could also promote viral gene activation. Finally, we showed that latent HIV-1 expression could also be stimulated by CRISPR-mediated activation of endogenous factors not previously implicated in HIV-1 pathogenesis but whose expression could nonetheless reactivate viral gene expression. Collectively, these results demonstrate that CRISPR systems are potentially effective tools for inducing latent HIV-1 expression and that their use, in combination with antiretroviral therapy, could lead to improved therapies for HIV-1 infection.