Molecular transmission network and drug resistance analysis of 404 HIV-1 cases infected through commercial heterosexual contact (2020–2024)

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, CRF07_BC 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 CRF85_BC 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 CRF07_BC 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.