Molecular genetics and epidemiological characteristics of HIV-1 epidemic strains in various sexual risk behaviour groups in developed Eastern China, 2017–2020

In this study, we conducted a detailed molecular epidemiological analysis of HIV-1 epidemic strains in various sexual risk behaviour groups in a developed area in eastern China based on phylogenetic inference, molecular transmission networks, and Bayesian analyses. A total of 1083 pol sequences (91.23%, 1083/1187) from newly diagnosed HIV-1-positive patients from 2017 to 2020 were successfully obtained and involved thirteen HIV-1 subtypes, in which the major HIV-1 subtypes were CRF07_BC (36.10%, 391/1083) and CRF01_AE (34.63%, 375/1083). 485 individuals (44.78%,485/1083) formed 146 clusters in the network. Of which CRF07_BC showed extensive clustering driven by men who have sex with men (MSM) within larger networks, CRF01_AE and other subtypes were generally driven by small clusters (SCs) and medium clusters (MCs) among various risk groups. Through Sankey diagrams, the MSM group infected with CRF07_BC had a greater impact on the non-commercial heterosexual group among all cross-risk groups. In addition, a higher number of key individuals infected with CRF07_BC (40.22%, 74/127), suggests the crucial role of CRF07_BC-infected individuals as a local epidemic driver in the context of a mixed HIV-1 epidemic. Further Bayesian analysis confirmed that CRF07_BC was introduced into Jiaxing city from other provinces multiple times and spread rapidly among MSM and heterosexual individuals. Overall, our study provided some insights and information to explore the local transmission dynamics of HIV-1 epidemic strains involving various sexual risk groups, and emphasize that it is necessary to conduct in-depth research and precise intervention targeting key clusters/ individuals to effectively block the continued transmission of AIDS.