ABSTRACT
Objective:To understand the molecular transmission characteristics of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome(AIDS) patients in the mountainous area of southwest Zhejiang Province(Lishui city).Methods:A total of 147 blood samples were collected from newly-diagnosed HIV-1 infected who received no antiviral therapy, and pol gene was amplified, followed by sequencing. MEGA6.0 software was used to construct phylogenetic tree and determine gene subtypes. HIVDB online was used to analyze drug resistance mutation, then the pairwise genetic distance(GD) was calculated and the opitimal threshold of GD was selected, finally the molecular transmission network was constructed by Cytoscape3.7.0 software. Chi-square or Fisher′s exact probability method was used for statistical analysis. Results:A total of 134 sequences were obtained successfully, and nine subtypes were detected. The dominant subtypes were CRF08_BC (34.33%, 46/134), CRF01_AE (29.85%, 40/134) and CRF07_BC (23.88%, 32/134). It also found that age, registered residence, education level and transmission route had significant differences in distribution of subtypes ( P<0.05). Nineteen drug resistance individuals were found, and the total drug resistance rate was 14.18% (19/134). The HIV-1 molecular transmission network was plotted based on 1.2% GD threshold. A total of 15 transmission clusters (cluster size ranging from 2 to 29) were found. The network access rate was 49.25% (66/134), mainly including male (75.76%, 50/66), heterosexual (81.82%, 54/66) and patientsrinfected with CRF08_ BC (50.00%, 33/66). A transmission cluster including two cases of female sex workers and seven cases of drug resistance was identified, in which the average age of the patients was 57.21 years old and the average degree value was 22.7, and the cases were mainly infected through heterosexual contact (96.55%, 28/29). The highest homology of the sequences in the cluster was in Yunnan. Conclusions:The HIV-1 subtypes were diverse in the mountainous area of southwest Zhejiang Province(Lishui city). Drug resistant transmission had reached a moderate epidemic level. There were molecular transmission clusters with the aggregation characteristics of elderly clients in specific regions. It was urgent to formulate and implement precise intervention strategies to curb the spread of HIV.