The HIV integrase inhibitor, dolutegravir (DTG), in the absence of eliciting integrase (int) resistance, has been reported to select mutations in the virus 3'-polypurine tract (3'-PPT) adjacent to the 3'-LTR U3. An analog of DTG, cabotegravir (CAB), has a high genetic barrier to drug resistance and is used in formulations for treatment and long-acting pre-exposure prophylaxis. We examined whether mutations observed for DTG would emerge in vitro with CAB. HIV-1IIIB was cultured in paired experiments of continuous high (300 nM) CAB initiated 2 h or 24 h after infection. After eight months of CAB treatment, no int resistance was detected. Conversely, HIV RNA 3'-PPT mutants were detected within one month and were the majority virus by day 98. The appearance of 3'-PPT variants coincided with a rapid accumulation of HIV 1-LTR and 2-LTR circles. RNA amplification from the 3'-LTR TAR identified transcripts crossing 2-LTR circle junctions, which incorporated the adjacent U5 sequence identical to the 3'-PPT mutants. 3'-PPT variants were only identified in LTR circles and transcripts. Additionally, we found evidence of linear HIV and LTR circle recombination with human DNA at motifs homologous to 3'-PPT sequences. HIV persistence under CAB was associated with transcription and recombination of LTR circle sequences.
Keywords: 3′-PPT; CAB; HIV recombination; LTR circles; cabotegravir resistance.