title: The explosive human immunodeficiency virus type 1 epidemic among injecting drug users of Kathmandu, Nepal, is caused by a subtype C virus of restricted genetic diversity.
abstract: An explosive epidemic of human immunodeficiency virus type 1 (HIV-1) has been documented among the injecting drug user population of Kathmandu, Nepal, whose seropositivity rate has risen from 0 to 40% between 1995 and 1997. By using Catrimox to preserve whole-blood RNA at ambient temperature for transportation, HIV-1 envelope V3-V4 sequences were obtained from 36 patients in this group. Analysis of the sequences indicated a homogenous epidemic of subtype C virus, with at least two independent introductions of the virus into the population. Viral diversity was restricted within two transmission subclusters, with the majority of variation occurring in V4. Calculation of the synonymous-to-nonsynonymous mutation ratio (Ks:Ka) across this region showed that significant evolutionary pressure had been experienced during the rapid horizontal spread of the virus in this population, most strongly directed to the region between V3 and V4.
authors.affiliation: AIDS Molecular Biology Unit, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria 3078, Australia. oelrichs@loxinfo.co.th
authors.forename: R B
authors.initials: RB
authors.lastname: Oelrichs
authors.forename: I L
authors.initials: IL
authors.lastname: Shrestha
authors.forename: D A
authors.initials: DA
authors.lastname: Anderson
authors.forename: N J
authors.initials: NJ
authors.lastname: Deacon
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D018076:DNA, Complementary / Q000235:genetics; D004196:Disease Outbreaks; D005260:Female; D015752:Genes, env; D014644:Genetic Variation; D015699:HIV Envelope Protein gp120 / Q000235:genetics; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology / Q000821:virology*; D015497:HIV-1 / Q000145:classification* / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D009390:Nepal / Q000453:epidemiology; D010446:Peptide Fragments / Q000235:genetics; D010802:Phylogeny; D012367:RNA, Viral / Q000097:blood; D017422:Sequence Analysis, DNA; D013048:Specimen Handling; D015819:Substance Abuse, Intravenous / Q000150:complications*
chemical_list: D018076:DNA, Complementary; D015699:HIV Envelope Protein gp120; C059762:HIV envelope protein gp120 (305-321); D010446:Peptide Fragments; D012367:RNA, Viral