Molecular transmission network analysis of HIV-1 among older adults in Central China: a cross-sectional study in Shaodong City.

OBJECTIVE

The ageing population poses emerging challenges to HIV prevention, particularly in regions with high proportions of older adults. We conducted a cross-sectional study of 513 newly diagnosed HIV-infected individuals in Shaodong City, Hunan Province, China, between 2021 and 2025, with a focus on individuals aged ≥60 years.

METHODS

HIV-1 pol sequences were amplified, sequenced, and analyzed for subtype distribution and transmitted drug resistance (TDR). Molecular transmission networks were constructed using a 0.5% genetic distance threshold, and clusters were classified as large (≥10 nodes), medium (5-9 nodes), or small (<5 nodes).

RESULTS

CRF85_BC was the predominant subtype (32.55%), and a total of 37 transmission clusters were identified, with the two largest clusters comprising 99 and 19 nodes, respectively. High-risk nodes, defined as those with a transmission network score (TNS) ≥ 0.75 and degree ≥4, were primarily older male farmers engaged in heterosexual commercial sex. The overall TDR prevalence was 10.53%, with NNRTI resistance predominating, and K103N being the most frequent mutation.

CONCLUSION

Our findings indicate that HIV transmission among older adults exhibits substantial clustering, largely driven by commercial sexual activity, and highlight the importance of molecular network analysis for identifying high-risk individuals and guiding targeted prevention interventions. Continuous surveillance of TDR within active clusters is critical for optimizing antiretroviral therapy strategies and mitigating onward transmission.