Identification of new circulating recombinant form of HIV-1 CRF139_02B in Japan, and search for the origin

Many circulating recombinant forms (CRFs) of HIV-1 have been reported, resulting in complex molecular epidemiology of HIV-1 infection. In this study, we newly identified CRF139_02B in Japan from 4 cases of antiretroviral therapy na & iuml;ve people living with HIV. Near full-length genome sequences of CRF139_02B were determined using Illumina MiSeq. Basic Local Alignment Search Tool (BLAST) revealed that there were several sequences having the same breakpoints as CRF139_02B in the UK and Nepal, though its full-length genome sequences were not available. Maximum clade credibility tree analysis using the region of protease and reverse transcriptase of HIV1 estimated that the time to the most recent common ancestor of CRF139_02B variants found in Japan was 2017.6 (95% highest posterior density interval: 2015.9-2019.3), and that among the UK, Nepal, and Japan was 2010.4 (2007.82012.5). These results suggested that CRF139_02B circulated in Japan recently and domestically. Furthermore, the origin of CRF139_02B could be in the UK. Because there is a possibility that further international circulation of CRF139_02B may be observed in the near future, continuous monitoring of HIV-1 molecular epidemiology will be needed.