15th International AIDS Conference Bangkok, Thailand - July 11-16, 2004

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. MoOrA1007)

Wirachsilp P, Arworn D, Kaoriangudom S, Siraprapasiri T, Tanprasertsuk S, Sutthent R
NHRBC, Department of Microbiology, Siriraj Hospital, Mahidol University, Bangkok, Thailand

BACKGROUND: HIV-1 CRF01_AE and subtype B have been circulating in Thailand. Inter-subtype recombinants of HIV are expected to emerge in geographic regions where there is widespread of HIV-1 epidemic such as Thailand. Recently, CRF15_01B, the intersubtype CRF01_AE/B recombinant strain, was reported in heterosexual and IDU groups in northern and eastern part of Thailand.

METHODS: HIV-1 RNA was extracted from plasma of 433 newly identified HIV sero-positive Thai individuals from 21 provinces countrywide in year 2002. Nucleotide sequences of C2-V4 region of env gene and p17-p24 region of gag gene were analyzed by clustalX and PAUP4.0 software. The phylogenetic tree was constructed with 500 bootstrap replicates.

RESULTS: Phylogenetic study of 419 (96.7%) CRF01_AE sequences demonstrated 6 clusters (E1-E6). Sequences in E1 cluster (n=164, 39.1%) did not relate to either CRF01_AE sequences from neighboring countries or Thai E prototype. Sequences in E2 cluster (n=33, 7.9%) related to isolates from Cambodia, Vietnam, and Myanmar and those in E3 cluster (n=37, 8.8%) related to isolates from Cambodia and Vietnam. Sequences in E4 (n=45, 10.7%) and E5 (n=57, 13.6%) related to Thai isolates, 93TH253 and CM244, respectively. Sequences in E6 cluster (n=83, 19.8%) related to CM240 isolate from Thailand and Vietnam isolates. Among 14 (3.3%) subtype B strains, 3 strains showed discordant subtype between gag and env gene and clustered with CRF15_01B. Two of them were from heterosexual risk group in northeastern part and the other was from southern part of Thailand.

CONCLUSIONS: There were geographically distinct variants of HIV-1 CRF01_AE in Thailand. Discordant subtype between gag and env sequences in patients from different part of country indicated the circulation of recombinant form of HIV-1 in Thailand. These findings have implications for the important of HIV-1 subtype surveillance in Thailand and using of rapid and simple method for HIV-1 subtype determination.

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MoOrA1007

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