title: Independent introduction of two major HIV-1 genotypes into distinct high-risk populations in Thailand.
abstract: To investigate the genetic heterogeneity and epidemiological distribution of human immunodeficiency virus type 1 (HIV-1) in Thailand, we determined proviral sequences for 63 HIV-1-infected patients in various risk groups from all over the country between April and July, 1991. Two distinct genotypes of HIV-1, A and B, were found to segregate by mode of transmission. Of 29 sexually infected patients, 25 (86%) had HIV-1 of genotype A and 4 (14%) had genotype B. Among 29 injecting drug users, probably parenterally infected, only 7 (24%) had genotype A and 22 (76%) had genotype B. This segregation is unlikely to have arisen by chance (p < 0.001). No patient was found to have dual infection. Nucleotide divergence averaged 3.4% among genotype-A-infected patients and 3.5% among genotype-B-infected patients, but 22.0% between the genotypes. 37 of 40 isolates (both genotypes) had the GPGQ tetrapeptide at the tip of the V3 loop, which is common in African HIV-1 strains but rare in North American and European strains, where the GPGR motif predominates. These findings suggest that the waves of HIV-1 infection in injecting drug users and in sexually infected patients in Thailand may not be epidemiologically linked. The nucleotide divergence data point to the separate introductions of the two genotypes in Thailand. Further studies in Thailand and neighbouring countries will be useful in the design and selection of candidate HIV vaccines.
authors.affiliation: Division of HIV/AIDS, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333.
authors.forename: C Y
authors.initials: CY
authors.lastname: Ou
authors.forename: Y
authors.initials: Y
authors.lastname: Takebe
authors.forename: B G
authors.initials: BG
authors.lastname: Weniger
authors.forename: C C
authors.initials: CC
authors.lastname: Luo
authors.forename: M L
authors.initials: ML
authors.lastname: Kalish
authors.forename: W
authors.initials: W
authors.lastname: Auwanit
authors.forename: S
authors.initials: S
authors.lastname: Yamazaki
authors.forename: H D
authors.initials: HD
authors.lastname: Gayle
authors.forename: N L
authors.initials: NL
authors.lastname: Young
authors.forename: G
authors.initials: G
authors.lastname: Schochetman
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA; D005260:Female; D005838:Genotype; D015658:HIV Infections / Q000453:epidemiology / Q000382:microbiology / Q000635:transmission; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000235:genetics; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011159:Population Surveillance; D012111:Residence Characteristics; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012703:Serotyping; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology; D013785:Thailand / Q000453:epidemiology
chemical_list: D009841:Oligonucleotides; D004247:DNA