CRF07_BC Strain Dominates the HIV-1 Epidemic in Injection Drug Users in Liangshan Prefecture of Sichuan, China

Abstract

The Liangshan prefecture in Sichuan province is an area in China severely affected by the HIV epidemic, with intravenous drug use (IDU) as the main risk factor. No reports on HIV subtypes prevalent in IDUs in Liangshan prefecture could be found. In this study, we have characterized the genotypes of HIV-1 in the IDU population in Liangshan prefecture and further determined the phylogenetic relationship of the CRF07_BC strains to HIV-1 sequences from the other regions of China, including Xinjiang and Yunnan provinces, to explore the pattern and possible diffusion pathway of HIV-1 in these regions. HIV-1-seropositive drug-naive IDUs identified in Liangshan prefecture, Sichuan province were enrolled in 2009. Full-length gag and pol genes were amplified by reverse transcription and nested PCR and then sequenced. All of the sequences were subtyped. Phylogenetic trees were constructed using the neighbor-joining and maximum likelihood methods. Divergence times were estimated using a Bayesian molecular clock approach. CRF07_BC was found to be the predominant strain in IDUs in Liangshan prefecture (95.5%). The CRF07_BC strains from Liangshan prefecture were found to be intermixed with those from Yunnan province in phylogenetic trees. The CRF07_BC sequences from Xinjiang province can be grouped into several clusters, suggesting that the expansion of the CRF07_BC epidemic in Xinjiang province was the result of a local epidemic driven by multiple independent introductions in the late 1990s. Only low-level drug-resistant viruses were found in the IDU population. CRF07_BC strains from Liangshan prefecture were more similar to those from Yunnan province than those from Xinjiang province. This finding will contribute to our understanding of the distribution, the evolution, and the potential source of CRF07_BC founder strains, and will also provide useful information for the development of strategies to prevent transmission.

Prevalence of HIV-1 Drug Resistance among Patients with Antiretroviral Therapy Failure in Sichuan, China, 2010-2016

“…However, in the study of drug resistance in Butuo County of Liangshan Prefecture in 2013, 23 of the 24 were successful sequencing samples CRF07_BC (95.83%) for subtype. Though the number of samples was smallest, the conclusion was consistent with the molecular epidemiological survey of Liangshan Prefecture in 2009 (Li et al 2015). The most of infected people in Butuo County were the Yi people, and most of them were farmers, whose education level was low.…”

Overview of HIV molecular epidemiology among people who inject drugs in Europe and Asia

“…Subtype C from India and subtype B from Thailand caused the first outbreaks among PWID in Yunnan in the late 1980s and early 1990s (Han et al, 2015; Piyasirisilp et al, 2000; Tee et al, 2008; Zheng et al, 1994). Subtype B', that soon became the predominant B clade in China (Graf et al, 1998; Lau et al, 2007), and subtype C recombined to generate two related but distinct strains, CRF07_BC and CRF08_BC, which trace their origin to Yunnan and fueled the epidemic among PWID in Northwestern, Southeastern and Northeastern China, and to Taiwan (CRF07_BC) (Han et al, 2015; He et al, 2012; Laeyendecker et al, 2005; Lau et al, 2007; Li et al, 2015; Lin et al, 2006; Piyasirisilp et al, 2000; Takebe et al, 2010; Tee et al, 2008). CRF07_BC has also become the predominant strain among PWID (>80%) in Taiwan (Chen et al, 2012, 2010; Huang et al, 2014; Lin et al, 2006).…”

Molecular surveillance of HIV, HBV, and HCV amongst blood donors in five Chinese regions

“…Therefore, the monitoring of URFs will be helpful to the surveillance of new CRFs. CRF01_AE was found to be dominant in the transmitted sexual population in China (37), while CRF_07BC and CRF_08BC were mainly prevalent in IDU population (38). In addition, CRF07_BC was the most predominant strain in the north-western region, which suggested a lack of incoming transmissions from other regions (4).…”