Background HIV/AIDS remains a significant public health challenge. This study aimed to investigate the molecular transmission network and drug resistance characteristics among HIV-1 infected individuals through commercial heterosexual contact in Yubei District which located in a southwest city in China, thereby assessing HIV transmission risks in the region. Methods Blood samples were collected from newly diagnosed HIV-1 patients in Yubei District in Chongqing city between 2020 and 2024, all of whom acquired the infection through commercial heterosexual contact. The HIV-1 pol region was amplified and sequenced to construct a phylogenetic tree. Drug resistance mutation sites were obtained by comparing with the Stanford Drug Resistance database. A molecular transmission network was constructed using a genetic distance threshold of 1. 3%. Univariate and multivariate logistic regression analyses were used to determine potential factors influencing network entry and the formation of large clusters. Results Among the 404 sequences, CRF07BC was the predominant genotype (55. 9%). The pretreatment drug resistance rate was 4. 70% for all cases of commercial heterosexual exposure. Molecular network analysis revealed that 223 sequences (with an entry rate of 55. 2%) formed 39 clusters, including 6 large clusters with more than 10 nodes. Multivariate logistic regression models identified age ≥ 60 years, household registration in Yubei District, and CRF85BC genotype as risk factors for network inclusion and large cluster formation. Additionally, the study identified a transmission cluster with significant geographic aggregation, featuring one female sex worker who posed a high transmission risk. Conclusion HIV-1 infections transmitted through commercial heterosexual contact exhibit pronounced geographic clustering, with over half of the cases belonging to the CRF07BC genotype. Although the pretreatment drug resistance prevalence remains low, establishing a sustained resistance surveillance system remains essential. Targeted management and precise interventions are required for identified high-risk transmission networks to effectively curb further spread of HIV.
Ma et al. (Wed,) studied this question.