The origin and dissemination of HIV-1 subtype B on Hainan Island, South China, 2007-2024.

BACKGROUND

HIV-1 subtype B, introduced to mainland China at an early stage, rapidly spread among commercial plasma donors and heterosexuals (HETs) during the 1990s. It was first identified in Hainan, which has a population of 10 million, in 2007. Nevertheless, there is a paucity of data about the molecular-epidemiological characteristics, spatial origins, and transmission patterns of this strain on the island of China.

METHODS

Pol sequences for HIV-1 subtype B from Hainan Island (2007-2024) were obtained from our research and global databases. An analysis of phylogenetic data, molecular clock models, and a Bayesian coalescent-based approach was performed to investigate how HIV-1 subtype B was introduced and disseminated on this island.

RESULTS

A total of 76 sequences were obtained from Hainan Island, of which 52.63% were collected from men who have sex with men (MSM). Phylogenetic analysis demonstrated that HIV-1 subtype B circulating on the island was closely related to HIV-1 sequence lineages in Guangdong (22.84%, 127/556), Hubei (12.59%, 70/556), and Beijing (14.03%, 78/556), indicating multiple introductions from various cities in China. Bayesian time-scaled phylogenetic reconstructions revealed that 27 Hainan sequences were together in clusters [posterior probability (PP) > 0.90], and 18 Hainan sequences were intermixed in larger clades containing sequences from other provinces (PP > 0.90). Bayes factors (BF) demonstrated that subtype B on the Island originated from Guangdong Province (BF > 100) in 1999.9 (95% HPD:1996.7, 2002.7) and Hubei Province (BF > 100) in 2007.9 (95% HPD:2004.4, 2011.2). Subsequently, HIV-1 subtype B was introduced to Beijing from the island (BF > 100). The analysis of viral migration patterns among risk subgroups revealed that subtype B was introduced to the island by MSMs (BF > 100). Within the island, this strain was from MSM to HETs (BF > 100).

CONCLUSION

Using Hainan Island as a case study, our findings shed light on the intricate evolution and transmission dynamics of HIV-1 subtype B on the island, revealing crucial insights for HIV prevention efforts in the future.