Longitudinal molecular network analysis in Guangxi: implications for HIV control

OBJECTIVE: Guangxi faces a persistent HIV epidemic driven by heterosexual transmission and aging populations. This study uses molecular network to examine network topology and dynamics over time, providing insights for HIV control strategies. METHODS: A total of 9751 samples were collected from HIV-infected individuals across Guangxi between 2005 and 2024. HIV pol gene was extracted, and molecular networks were constructed based on the TN93 genetic distance. Network indicators, including clustering rate, network density, degree distribution, transmission rate, and proportional detection rate, were calculated across four time periods (≤2009, 2010-2014, 2015-2020, 2021-2024). Stratified analyses were further conducted. RESULTS: Population characteristics revealed pronounced epidemic aging (individuals aged ≥50 years increased from 10.6% to 62.3%) and a predominance of heterosexual transmission (rising from 50.4% to 90.6%). The network structure evolved from centralized to fragmented: clustering rate declined from 70.64% to 49.92%, network density decreased from 0.084 to 0.037, and the proportion of nodes with degree ≥4 fell from 37.50% to 13.34%. Degree distribution narrowed, suggesting a reduction in superspreading. Transmission rate and proportional detection rate also shifted downward, indicating suppressed network expansion in later periods. Stratified analyses showed higher clustering rates among heterosexual transmission, older adults, individuals with low education, and farmers, although overall declines were consistent across subgroups. CONCLUSIONS: This study highlights evolving HIV molecular network characteristics in Guangxi after three rounds of AIDS Conquering Project, offering evidence of reduced complexity and intensity over time. These findings inform planned HIV control efforts, underscoring the need for targeted interventions and enhanced monitoring, particularly for older, less-educated farmers.