# High genetic diversity of HIV-1 pol region and molecular transmission networks among people living with HIV-1 in Haikou, South China, 2005–2022

## TL;DR

This study examines the genetic diversity of HIV-1 in Haikou, China, and identifies key subtypes involved in transmission networks to inform prevention strategies.

## Contribution

The study reveals the role of specific HIV-1 subtypes in molecular transmission networks using genetic data from 2005–2022.

## Key findings

- CRF07_BC and CRF01_AE are the most common HIV-1 subtypes in Haikou.
- CRF65_cpx shows a strong association with high transmission network scores.
- Certain subtypes are more likely to form and spread within transmission clusters.

## Abstract

Hainan is experiencing a continuous increase in newly diagnosed HIV-1 infections, highlighting the need for a comprehensive understanding of local transmission dynamics. This study aims to elucidate the genetic diversity and potential HIV-1 molecular transmission networks among people living with HIV-1 in Hainan, China.

We used the HIV-TRACE to infer the transmission dynamics of HIV-1 at a 1.5% gene distance threshold. The role of HIV-1 diversity in transmission networks was assessed through node influence measurement and centrality analysis.

A total of 986 pol sequences were included, with CRF07_BC (43.71%) and CRF01_AE (37.12%) emerging as the predominant subtypes. Of these, 586 (59.43%) were clustered into the transmission networks, forming 83 clusters with 155 nodes having high transmission network scores (HTNS). CRF07_BC (adjusted odds ratio, aOR: 1.585, 95%CI: 1.189– 2.113) and CRF65_cpx (aOR: 9.513, 95%CI: 3.694– 24.499) were more likely to cluster in networks and exhibit nodal centrality than CRF01_AE. The CRF65_cpx (88.46%) were more likely to be HTNS (aOR: 57.302, 95%CI:16.869– 194.643) than CRF07_BC.

This study highlights the high genetic diversity of HIV-1 and its central role in transmission networks, advocating for targeted prevention strategies and community engagement for high-risk transmission populations, particularly focusing on subtypes CRF07_BC and CRF65_cpx.

The online version contains supplementary material available at 10.1186/s12879-025-11184-y.