Abstract
The increasing proportion of HIV-1 infections transmitted via non-marital non-commercial heterosexual contact (NMNCHC) in China necessitates a deeper understanding of its local characteristics. This study investigated the epidemiological, molecular network, and drug-resistant profiles among 400 newly diagnosed HIV-1 patients infected via non-marital heterosexual contact (NMHC), specifically its non-commercial subtype, in Lishui from 2020-2024. HIV-1 pol gene sequences were analyzed for subtypes, drug resistance mutations, and transmission clusters using phylogenetic and network methods (genetic distance threshold: 0.9%). The overall prevalence of transmitted drug resistance (TDR) was 13.3%, an intermediate level exceeding the national average, driven predominantly by NNRTI resistance (6.3%). High-level resistance to NVP (3.0%) and EFV (2.75%) was observed. CRF08_BC (43.8%) was the dominant subtype. Multivariate analysis identified female gender and higher education as significant risk factors for NMNCHC acquisition. Molecular network analysis incorporated 55.3% of cases, revealing clusters predominantly composed of middle-aged and elderly males, with CRF08_BC and CRF01_AE showing higher NMNCHC transmission risk within networks. These findings underscore an evolving epidemic with significant TDR and highlight the urgent need for targeted interventions, including enhanced resistance surveillance and focused strategies for the concealed NMNCHC population, to curb local HIV-1 transmission.