Using molecular network analysis to understand current HIV-1 transmission characteristics in an inland area of Yunnan, China

Abstract

HIV-1 molecular surveillance provides a new approach to explore transmission risks and targeted interventions. From January to June 2021, 663 newly reported HIV-1 cases were recruited in Zhaotong City, Yunnan Province, China. The distribution characteristics of HIV-1 subtypes and HIV-1 molecular network were analysed. Of 542 successfully subtyped samples, 12 HIV-1 strains were identified. The main strains were CRF08_BC (47.0%, 255/542), CRF01_AE (17.0%, 92/542), CRF07_BC (17.0%, 92/542), URFs (8.7%, 47/542), and CRF85_BC (6.5%, 35/542). CRF08_BC was commonly detected among Zhaotong natives, illiterates, and non-farmers and was mostly detected in Zhaoyang County. CRF01_AE was frequently detected among married and homosexual individuals and mostly detected in Weixin and Zhenxiong counties. Among the 516 pol sequences, 187 (36.2%) were clustered. Zhaotong natives, individuals aged ≥60 years, and illiterate individuals were more likely to be found in the network. Assortativity analysis showed that individuals were more likely to be genetically associated when stratified by age, education level, occupation, and reporting area. The genetic diversity of HIV-1 reflects the complexity of local HIV epidemics. Molecular network analyses revealed the subpopulations to focus on and the characteristics of the risk networks. The results will help optimise local prevention and control strategies.

Keywords: HIV-1; assortativity; molecular network; spatial analysis.

Figure 1.

Spatial distribution of the major HIV-1 genotypes in Zhaotong City. The dot density maps for CRF01_AE, CRF07_BC, CRF08_BC, CRF85_BC, and URFs. One dot represented 0.03% of the total subtyped cases. According to the local spatial autocorrelation analysis, the areas outlined in blue are the high–high aggregation area. Administrative boundary data were downloaded from the National Catalogue Service for Geographic Information (https://www.webmap.cn). The map content approval number: ZhaotongS(2022)6.

Figure 2.

Characteristics of the HIV-1 molecular network in Zhaotong City. (a) Distribution of genetic transmission clusters by cluster size. (b) Distribution of sequence pairs by genetic distance. (c) Distribution of nodes in clusters by links.

Figure 3.

Assortativity analysis of the linked individuals in the HIV-1 molecular network in Zhaotong City. (a) Left panel: HIV-1 molecular clusters coded by age group. Right panel: assortativity analysed by age group. (b) Left panel: HIV-1 molecular clusters coded by educational level. Right panel: assortativity analysed by education level. (c) Left panel: HIV-1 molecular clusters coded by occupation. Right panel: assortativity analysed by occupation. (d) Left panel: HIV-1 molecular clusters coded by report area. Right panel: assortativity analysed by report area. The grey dotted line represents the 5% significance level. The pink vertical line represents the corresponding assortativity.