Molecular epidemiology of HIV-1 subtypes and drug resistant strains in Taiwan.

The Taiwanese government has provided free highly active antiretroviral therapy since April 1997. Previously, we have reported on the molecular epidemiology of HIV-1 in Taiwan from 1988 to 1998. In addition, an outbreak of circulating recombinant form (CRF) 07_BC among intravenous drug users was noted in 2004. Therefore, the purposes of this study were to elucidate the distribution of HIV-1 subtypes among different high-risk groups in Taiwan from 1999 to 2000 and to conduct surveillance on drug resistance among treatment naïve patients from 1997 to 2000. Blood samples from 239 HIV-1/AIDS patients and their subtypes were examined using DNA sequencing and phylogenetic analysis. The results showed that among 226 male patients, 213 (94.2%) had subtype B, 11 (4.9%) had CRF01_AE, 1 had unique recombinant strain related to both CRF07_BC and CRF08_BC (strain T12-99TW) and 1 had CRF08_BC (strain L9312-00TW). The patients infected with T12-99TW and L9312-00TW were intravenous drug users and had needle-sharing experiences in Yunnan Province, China. Of the 13 HIV-1-infected females, 7 (53.8%) had subtype B, 5 (38.5%) had CRF01_AE, and 1 (7.7%) had subtype C. Phylogenetic analysis demonstrated that the neither strain T12-99TW nor L9312-00TW clustered with CRF07_BC strains isolated from Taiwanese intravenous drug users in 2004. In addition, 126 treatment naïve patients were selected for genotypic DR analysis and the results showed that 4.3% (2/47) homosexual males had M184V mutations. This is the first report on the identification of CRF08_BC and a unique recombinant strain related to both CRF07_BC and CRF08_BC in Taiwan.