Molecular Epidemiological Survey Of Newly Reported HIV-1 Infection In Zhaotong City,Yunnan Province

Objectives: Zhaotong City is one of key areas for HIV/AIDS prevention and treatment in Yunnan Province,to understand the characteristics of HIV-1 transmission and related influencing factors in Zhaotong City and grasp the transmission pattern,combined with the epidemiological survey,this study conducted a molecular epidemiological survey of newly reported HIV-1 infection in Zhaotong City from January to June 2021.Methods: Blood samples were collected from newly reported HIV-1infection in Zhaotong City from January to June 2021,from which viral RNA was extracted.The pol,gag and env gene sequences were amplified and sequenced.Demographic information downloaded from the Integrated AIDS Control Information System and information collected in questionnaires were integrated and matched to sequences data.Sequencing was completed using Sequencher 5.1 software,sequences were compared and cleaned up using Bio Edit 7.0 software,and phylogenetic trees were constructed using Mega X software to determine genotypes.Spatial analysis was performed using Geo Scene software.Using the obtained pol gene sequences,the molecular network was constructed by phylogenetic tree combined with genetic distance.The factors entrying into the network were analysed.A network-level measure of assortativity was used to analyse whether individuals with the same attributes in the network tend to connect to each other.Transmitted drug resistance was analyzed using the Calibrated Population Resistance Tool(CPR).Results:1.A total of 663 samples of newly reported HIV-1 infection in Zhaotong City from January to June 2021 were obtained.After viral RNA extraction and amplification,495 gag,516 pol and 414 env sequences were obtained.Combining the genotyping results of the three genetic regions,542 samples were successfully genotyped.2.Of the 542 participants genotyped,most were reported in the eastern(35.6%,193/542)and southwestern(41.3%,224/542)sections of Zhaotong.The household registration of the most participants was in Yunnan Province.Among them,the oldest was 83 years old and the youngest was 17 years old.There was a high proportion of males,Han Chinese and those with primary education.The main occupation was farmer(83.0%,450/542),and heterosexual transmission was the main mode of infection(98.3%,533/542).3.Of the 542 samples successfully genotyped,a total of 12 genotypes were identified,including two subtypes,nine CRFs and URFs.CRF08＿BC was the predominant strains(47.0%,255/542),followed by CRF01＿AE(17.0%,92/542),CRF07＿BC(17.0%,92/542),URFs(8.7%,47/542),CRF85＿BC(6.4%,35/542),CRF125＿0107(1.8%,10/542),Subtype B(0.5%,3/542),Subtype C(0.4%,2/542),CRF55＿01B(0.4%,2/542),CRF64＿BC(0.4%,2/542),CRF101＿01B(0.2%,1/542)and CRF118＿BC(0.2%,1/542).4.The geographical distribution of the predominant HIV-1 genotypes showed difference.CRF07＿BC,CRF85＿BC and URFs were random distributed.CRF01＿AE and CRF08＿BC showed non-random positive correlation distribution and spatial aggregation.CRF01＿AE showed high-high aggregation within Zhenxiong and Weixin counties,and CRF08＿BC showed high-high aggregation in Zhaoyang district.5.CRF01＿AE and CRF08＿BC were statistically different in terms of demographic distribution characteristics.CRF01＿AE was more likely to be detected in married and homosexual transmission populations.Household registration in Yunnan,illiteracy and occupation other than farmer were significantly associated with CRF08＿BC infection.CRF07 BC was more likely to be detected among the individuals from other provinces.URFs and CRF85＿BC showed no significant distributional characteristics.6.The molecular network analysis showed that 187 out of 516 pol sequences entered the network,forming 61 clusters and 135 edges.Individuals aged ≥ 60 years,married and illiterate were more likely to have access to the network.7.Analysis of assortativity of the molecular networks showed that individuals in the same age group,with the same level of education,with the same occupation,and reporting within the same county tended to be connected to each other.8.The 516 samples which pol sequences were analysed for Surveillance Drug Resistance Mutation(SDRM),with single resistance mutations detected in 18 cases and no multiple resistance mutations.The prevalence of transmitted drug resistance was 3.5%(18/516),with the main mutation site being K103 N and Y181 C.Conclusions:1.HIV-1 genetics showed diversity in Zhaotong.A total of 12 genotypes,including two subtypes,nine CRFs and URFs,were identified.The predominant genotypes were CRF08＿BC,CRF07＿BC and CRF01＿AE in Zhaotong.2.CRF01＿AE and CRF08＿BC showed unique transmission characteristics in terms of demographics and spatial distribution.CRF01＿AE was more likely to be detected in married and homosexual transmission and tended to cluster in Zhenxiong and Weixin counties.Yunnan natives,illiteracy,and non-farmers were significantly associated with CRF08＿BC infection and tended to cluster in Zhaoyang district.CRF07 BC was more likely to be detected among the individuals from other provinces.3.Molecular network analysis showed that those aged ≥ 60 years,married and illiterate were more likely to be detected in the network,suggesting the need to strengthen surveillance of these populations and to develop appropriate interventions and prevention measures for different groups.4.The network-level measure,assortativity,showed that infected people in the same reporting area,same age group,same education level and same occupation were more correlated,and further constituting different subpopulations.The core prevention and control knowledge should be developed for these subpopulations,along with peer education and counselling.5.The prevalence of transmitted drug resistance was low in Zhaotong.In order to ensure the effectiveness of national free antiretroviral therapy,it is necessary to strengthen the detection and surveillance of drug-resistant strains to provide a scientific basis for adjusting the treatment regimens.