Spatiotemporal dynamics and cross-regional transmission network of HIV-1 CRF67_01B in six provinces in China

Cross-regional transmission of emerging recombinant strains poses a major challenge to HIV-1 prevention and control. HIV-1 CRF67_01B was first identified in China in 2013 and has since been reported in multiple provinces. This study aimed to elucidate the origin and cross-regional transmission pathways of this strain. HIV-1 pol sequences of CRF67_01B from Hangzhou were collected, along with publicly available sequences from other regions of China retrieved from the Los Alamos National Laboratory (LANL) HIV Sequence Database. A distance-based molecular network was constructed to identify putative transmission links. Bayesian phylogeographic methods, combined with Bayesian stochastic search variable selection (BSSVS), were used to infer historical migration pathways among provinces and estimate the time to the most recent common ancestor (tMRCA). A total of 183 CRF67_01B sequences sampled between 2011 and 2024 from six provinces were included. At a genetic distance threshold of 0.6%, the molecular network identified 24 transmission clusters, with an entry rate of 54.1% (99/183). Men who have sex with men (MSM) accounted for 91.9% (91/99) of individuals within clusters. Interprovincial putative transmission links were predominantly between Jiangsu and Hangzhou. Bayesian phylogeography inferred that CRF67_01B originated in Jiangsu Province around 2007. The strain exhibited exponential growth between 2009 and 2011, followed by a decline between 2017 and 2020, and then reached a plateau. Key migration pathways included Jiangsu to Hangzhou, Hangzhou to Anhui, and from Jiangsu, Hangzhou, Anhui, and Ningbo to Guangdong. CRF67_01B has formed a highly interconnected local transmission network and multiple cross-regional transmission links within the MSM population. The epidemic in Hangzhou is not an isolated event but is epidemiologically linked to surrounding and earlier epicenters. These findings highlight the importance of cross-regional joint prevention and control strategies targeting emerging HIV-1 recombinants, with a focus on hub cities and high-risk MSM populations.