Abstract / Summary
Pretreatment drug resistance (PDR) and acquired drug resistance (ADR) pose substantial challenges to antiretroviral therapy (ART). This study investigated the prevalence and molecular transmission characteristics of PDR and ADR among HIV-1-infected individuals in Qujing, Yunnan Province, China. Samples were collected from ART-failure individuals in 2023–2024 and treatment-naive individuals in 2024. The protease and reverse transcriptase regions of the HIV-1 pol gene were amplified by nested reverse transcription polymerase chain reaction. Positive amplicons were purified before Sanger sequencing. Genotypic drug resistance was interpreted using the Stanford HIV Drug Resistance Database. Molecular transmission network and Bayesian phylogenetic analyses characterized key transmission clusters and their evolutionary relationships. The prevalence of PDR was 10.85% (37/341). Non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance was the most common (7.62%), with E138 (7.33%), V179 (4.99%), and K103 (4.40%) as the predominant resistance-associated mutations. Protease inhibitor (PI) and nucleoside reverse transcriptase inhibitor (NRTI) resistance were 2.93% and 0.88%, respectively. The prevalence of ADR was 41.45% (308/743), with NNRTI resistance being most prevalent (37.55%), mainly associated with mutations K103 (24.76%), E138 (11.04%), and V179 (10.77%). NRTI resistance was 17.23%, with M184 (15.61%) predominant, while PI resistance was 2.56%. Molecular network analysis identified CRF08_BC as the predominant subtype and major genetic background of local transmission clusters, with E138 and K103 as frequently observed resistance-associated mutations. In the treatment-naive network, age ≥ 50 years was associated with higher odds of network inclusion (aOR = 7.499), while HIV-1 subtype and drug resistance status were also independently associated with network inclusion. In the network comprising both treatment-naive and ART-failure individuals, 81.25% (13/16) of networked PDR cases were located in mixed clusters containing ADR cases. Bayesian phylogenetic analysis supported sustained local circulation of CRF08_BC drug-resistant strains in Qujing. PDR and ADR in Qujing were predominantly characterized by NNRTI resistance, while CRF08_BC was the major subtype represented in local molecular transmission clusters. The co-clustering of PDR and ADR cases and the sustained local circulation of CRF08_BC drug-resistant strains highlight the need for strengthened drug resistance surveillance, timely management of virological failure, and targeted interventions for highly clustered populations such as older adults. Not applicable.