HIV-1 CRF07_BC transmission dynamics in China: two decades of national molecular surveillance

Abstract

By analyzing an unprecedentedly large, longitudinal HIV-1 CRF07_BC sequence dataset collected from China in the past two decades, we sought to build CRF07_BC lengthwise transmission networks, and understand its transmission dynamics. We divided CRF07_BC into two clusters based on phylogenetic analysis and an estimation of the pairwise genetic distance at 0.7%. Of 6,213 sequences, 3,607 (58.1%) linked to ≥1 other sequence. CRF07_BC was divided into two clusters: 07BC_O and 07BC_N. The 07BC_O is the original CRF07_BC, circulating in people who inject drugs (PWID) and heterosexuals, predominantly in southwestern and northwestern provinces of China. The 07BC_N is a new cluster, identified mostly in men having sex with men (MSM) in northern provinces of China. Bayesian analysis indicates that CRF07_BC has experienced two phases of exponential growth, which was first driven by 07BC_O then 07BC_N. Compared to 07BC_O, the proportion of the parameter of population transmission risk (TR) of 07BC_N has risen constantly. The power-law function analyses reveal that 07BC_N has increased over years with higher degree. In 07BC_N, only 13.16% of MSM were linked to other risk groups, but these links represent 41.45%, 54.25%, and 55.07% of links among heterosexual females, heterosexual males, and male PWID respectively. This study indicates that CRF07_BC has evolved into two clusters in China, and their distributions are distinct across risk groups and geographical regions. 07BC_N shows greater risk of transmission, and has gradually replaced 07BC_O. Furthermore, the results show that strengthening the MSM interventions could lower the rapidity of 07BC_N transmission in all risk groups.

Epidemiology and Molecular Transmission Characteristics of HIV in the Capital City of Anhui Province in China

“…In recent years, more and more CRF07_BC strains have been detected in MSM in China [26][27][28]. A study showed that CRF_07BC-N has a greater risk of transmission than CRF07_BC-O [13]. In our unpublished studies, we elucidated the transmission trend and scale of the CRF07_BC epidemic recombinant strain from IDUs to heterosexuals and then to MSM in China.…”

“…CRF07_BC subtype presented two distinct clusters in the phylogenetic tree: CRF07_BC-N, the subcluster that mainly spread among men who have sex with men (MSM); CRF07_BC-O, the subcluster that mainly spread in heterosexuals and injecting drug users (IDUs) [13]. A total of seven clusters were identified for the CRF01_AE subtype (clusters 1-7), plus an additional cluster classified as CRF01_AE-others [14].…”

Spatiotemporal Patterns of CRF07_BC in China: A Population-Based Study of the HIV Strain With the Highest Infection Rates

“…CRF07_BC-O was genetically and epidemiologically similar to the original CRF07_BC, circulating in IDUs and heterosexual individuals (HETs). It was also called CRF07_BC-unclustered or CRF07_BC-Others in some studies (9)(10)(11). CRF07_BC-N is the latest cluster derived from CRF07_BC-O and has mostly been reported in men who have sex with men (MSM).…”

“…CRF07_BC-N is the latest cluster derived from CRF07_BC-O and has mostly been reported in men who have sex with men (MSM). It has also been called CRF07_BC-Cluster 1 or CRF07_BC-MSM in some studies (9)(10)(11).…”

“…CRF07_BC was formed by recombination of subtype B' from Thailand and subtype C from India and has spread to many provinces in less than 30 years. Two epidemic clusters of CRF07_BC have since been identified in China ( 9 ). CRF07_BC-O was genetically and epidemiologically similar to the original CRF07_BC, circulating in IDUs and heterosexual individuals (HETs).…”