Abstract
BackgroundAs one of prevalence HIV-1 strains in IDUs in Asia, the origination and full transmission map of CRF07_BC is of great interested and remains unclear. In the study, we collected 769 CRF07_BC derived sequences (including 45 sequences generated in our laboratory) from 12 provinces in China for reconstructing transmission map. Meanwhile, ample historic epidemic evidences were also reviewed to assist sequences analysis.Methodology/Principal FindingsIn the study, we collected 769 CRF07_BC derived sequences and identified 138 independent sequences from 12 provinces in China for subsequent phylogeographic tree analysis, Bayes Factor test and the estimation of state tMRCA. The analyses demonstrated that CRF07_BC was originated in 1993 in IDU in Yunnan province and then initially spread to Guangxi (eastern neighbor to Yunnan) in 1994, to Xinjiang (northwest) in 1995 and to Sichuan (northern neighbor to Yunnan) in 1996. The subsequent transmissions occurred from Yunnan to Liaoning (northeast) in 1997 and to Jiangsu in 1998. Interestingly, after the early introduction of CRF07_BC into Guangxi, Xinjiang and Sichuan, these three regions served as secondary epicenters for further spreading into Gansu, Ningxia, Qinghai, Beijing and Hunan during 1999–2001. These analyzed results are in accordance with early epidemic investigations.Conclusions/SignificanceOur data not just reconstructed the migration map of CRF07_BC, but also firstly revealed the active roles of these secondary epicenters in the dynamic migration of CRF07_BC in China.
Highlights
Human immunodeficiency virus type 1 (HIV-1) circulating recombinant forms (CRFs) 07_BC (CRF07_BC), descended from subtypes B9 and C, represents one of the most prevalent HIV-1 strains in Asia and has been devastating in IDUs for more than a decade in China [1,2,3,4,5,6]
Our results revealed that CRF07_BC was originated in 1993 in Yunnan province before spreading to Guangxi in 1994, to Xinjiang in 1995 and to Sichuan in 1996, both the origin site and secondary epicenters with early introduction of CRF07_BC played important roles in the dynamic migration of CRF07_BC in China, and both drug traffic and population migration may have significantly contributed to the complicated transmission pattern of CRF07_BC
These data supported that CRF07_BC was originated in Yunnan where was demonstrated as the earliest epidemic region by epidemiological investigations [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29]
Summary
Human immunodeficiency virus type 1 (HIV-1) circulating recombinant forms (CRFs) 07_BC (CRF07_BC), descended from subtypes B9 and C, represents one of the most prevalent HIV-1 strains in Asia and has been devastating in IDUs for more than a decade in China [1,2,3,4,5,6]. Several important scientific questions remain elusive, including what evidences support Yunnan province as the origin site and epicenter of CRF07_BC, how did the transmission occur from the origin site to other regions, whether does unidentified and independent origin exist for CRF07_BC. To address those questions, more historic CRF07_BC sequences from early epidemic time and from different regions are required for analysis. Ample historic epidemic evidences were reviewed to assist sequences analysis
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