Romidepsin-induced HIV-1 viremia during effective antiretroviral therapy contains identical viral sequences with few deleterious mutations

OBJECTIVE: To investigate the origin of the HIV-1 viremia induced by the latency-reversing agent romidepsin. DESIGN: Six individuals on suppressive antiretroviral therapy received romidepsin administered intravenously once weekly for 3 consecutive weeks. CD4(+) T cells were obtained at baseline, following the second and third romidepsin infusion, and 10 weeks after the final romidepsin treatment. Plasma samples were collected 24 and 72 h after romidepsin infusions. METHODS: Single-genome sequencing of the env and p24-RT region was used to genetically characterize the virus from proviral DNA, the transcribed cell-associated RNA and the plasma RNA pool. RESULTS: In three of six participants with available plasma samples we identified plasma HIV-1 RNA sequences that were identical to DNA and/or cell-associated RNA sequences from peripheral blood CD4(+) T cells. In two participants, plasma RNA sequences contained expansions of identical sequences, corresponding to 62 and 100% of the total sequences, respectively. Plasma HIV-1 RNA had very low amounts of defective viruses compared to cell-associated RNA (odds ratio 20.85, P < 0.001) and to DNA (odds ratio 7.07, P = 0.011) during romidepsin therapy. CONCLUSIONS: Romidepsin induced transcription from proviruses in peripheral blood cells, which contributed to viremia in patients on suppressive therapy. The intermingling of these cell-associated HIV-1 RNA with DNA sequences indicates transcription from a diverse range of proviruses, but the expansions of identical viral plasma sequences with few defects indicate that the romidepsin-induced viremia arises from intact proviruses with highly similar or identical genetic backgrounds.