Primary HIV-1 drug resistance in the C-terminal domains of viral reverse transcriptase among drug-naïve patients from Southern Brazil

BackgroundMajor and accessory drug resistance mutations have been recently characterized in the C-terminal RT subdomains of HIV-1, connection and RNase H. However, their presence in treatment-naïve patients infected with HIV-1 non-B subtypes remains largely unknown.ObjectivesTo characterize the patterns of primary resistance at the C-terminal RT subdomains of HIV-1 infecting subjects in the southern region of Brazil, where HIV-1 subtypes B and C co-circulate.Study designPlasma viral RNA was extracted from patients recently diagnosed for HIV infection (2005–2008). The protease and reverse transcriptase regions were PCR-amplified and sequenced. Infecting HIV subtypes were assigned by phylogenetic inference and drug resistance mutations were determined following the IAS consensus and recent reports on C-terminal RT mutations.ResultsThe major mutation to NNRTI T369I/V was found in 1.8% of patients, while A376S was present in another 8.3%. In the RNase H domain, the compensatory mutation D488E was more frequently observed in subtype C than in subtype B (p=0.038), while the inverse was observed for mutation Q547K (p