Mutant Cas9-transcriptional activator activates HIV-1 in U1 cells in the presence and absence of LTR-specific guide RNAs.

CRISPR/Cas9 systems have been advanced as promising tools in the HIV eradication armamentarium for sequence-specific disruption or latency reversal. Enthusiasm is balanced by concerns about off-target host genome modification and effects on HIV evolution. In the chronically HIV-1-infected U1 promonocytic latency model, we have confirmed stimulation of HIV-1 production by a mutant Cas9-transcriptional activator and guide RNAs with two guide RNAs apparently more potent than one. However, significant increases were also observed in the absence of guide RNAs. We encourage continued careful evaluation of non-sequence-specific and off-target effects of Cas9-mediated approaches.