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AIDS Res Hum Retroviruses. 1998 Mar 1;14(4):319-27.

HIV type 1 in Thailand, 1994-1995: persistence of two subtypes with low genetic diversity.

Author information

1
Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.

Abstract

Extensive transmission of human immunodeficiency virus type 1 (HIV-1) in Thailand began in 1988, resulting in an estimated 800,000 cumulative infections by 1994. During 1994 and 1995, we collected blood specimens from 215 asymptomatic HIV-1-infected people with various risk behaviors from nine locations in all four regions of Thailand. HIV-1 subtypes and genetic heterogeneity were determined for 214 strains by a combination of direct DNA sequencing (n = 95), subtype-specific oligonucleotide probe testing (n = 201), and V3-loop peptide enzyme immunoassay (PEIA) (n = 214). All strains were either env subtype E (175; 81.8%) or B (39; 18.2%). Of the subtype B isolates, 37 (94.9%) were B' and 2 (5.1%) were more typical North American-like B strains (most subtype B strains in Thailand are part of a distinct subcluster within the subtype B branch on phylogenetic trees, termed B'; formerly Thai B or BB). Of 149 viruses from people with sexual risk behaviors from all regions, 146 (98.0%) were subtype E. Of 65 viruses from injecting drug users (IDUs), 29 (44.6%) were subtype E and 36 (55.4%) were subtype B, including 35 B' strains. There was regional variation in the proportions of subtypes E and B' among IDUs. The intrasubtype nucleotide divergence within the V3 and flanking regions of the env gene (mid-C2 to the start of the V4 region) was low (5.7% for subtype E and 3.1% for subtype B') compared with other HIV-1 group M subtypes from different countries. These findings of two subtypes with low heterogeneity indicate that Thailand may be a desirable setting for evaluating candidate HIV-1 vaccines. The mix of subtype E and B' strains among IDUs also offers the opportunity to study phenotypic differences between the two subtypes.

PIP:

The extensive transmission of HIV-1 in Thailand which began in 1988 led to an estimated 800,000 cumulative infections in the country by 1994. The authors collected blood specimens during 1994 and 1995 from 215 asymptomatic HIV-1-infected people with various risk behaviors from 9 locations across Thailand. HIV-1 subtypes and genetic heterogeneity were then determined for 214 strains using a combination of direct DNA sequencing, subtype-specific oligonucleotide probe testing, and V3-loop peptide enzyme immunoassay. 175 strains were subtype E and 39 were subtype B. 37 of the subtype B isolates were B' and 2 were more typical North American-like B strains. Of 149 viruses from people with sexual risk behaviors from all regions of the country, 146 were subtype E. Of 65 viruses from IV drug users (IVDUs), 29 were subtype E and 36 were subtype B, including 35 subtype B' strains. Regional variation was observed in the proportions of subtypes E and B' among IVDUs. The intrasubtype nucleotide divergence within the V3 and flanking regions of the env gene was 5.7% for subtype E and 3.1% for subtype B'. The finding of 2 HIV-1 subtypes with low heterogeneity suggests that Thailand may be an appropriate setting in which to evaluate candidate HIV-1 vaccines. The mix of subtype E and B' strains among IVDUs will also allow the study of phenotypic differences between the 2 subtypes.

PMID:
9519893
DOI:
10.1089/aid.1998.14.319
[Indexed for MEDLINE]

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