title: Temporal dynamics of HIV-1 circulating subtypes in distinct exposure categories in southern Brazil.
abstract: BACKGROUND
  The HIV-1 epidemic in Brazil is predominantly driven by subtype B. However, in Brazilian Southern region subtype C prevails and a relatively high AIDS incidence rate is observed. The aim of the present study was to assess the temporal dynamics of HIV-1 subtypes circulating in patients from distinct exposure categories in Southern Brazil. For this purpose 166 HIV-1 samples collected at the years of 1998 (group I) and 2005-2008 (group II) were analyzed.
  
  
  RESULTS
  Analysis of group I revealed statistically significant (p < 0.05) associations between MSM and subtype B as well as between IDU and subtype C; while no statistical significant association between HIV-1 subtypes and exposure category was verified for group II. An overall temporal increase in the prevalence of subtype C and BC recombinants was observed in both HET and MSM populations, accompanied by a proportional decrease in the prevalence of the pure subtype B.
  
  
  CONCLUSIONS
  The present study shows an association between HIV subtypes and exposure categories at the middle 1990s in Southern Brazil. Our findings suggest that MSM and IDU populations might have played a major role in the introduction and initial dissemination of subtypes B and C, respectively, in Southern Brazil. This study also suggests a trend towards homogenization of HIV-1 strains across distinct exposure categories as a consequence of an overall increase in the prevalence of subtype C and BC recombinants in both HET and MSM populations.
authors.affiliation: Centro de Desenvolvimento Técnico e Científico - CDCT, Fundação Estadual de Produção e Pesquisa em Saúde - FEPPS, Av, Ipiranga, 5400, 3° andar, CEP: 90610-000, Porto Alegre, RS, Brazil. sabrina.gene@gmail.com
authors.forename: Sabrina Em
authors.initials: SE
authors.lastname: Almeida
authors.forename: Rubia M
authors.initials: RM
authors.lastname: de Medeiros
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Junqueira
authors.forename: Tiago
authors.initials: T
authors.lastname: Gräf
authors.forename: Caroline P B
authors.initials: CP
authors.lastname: Passaes
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Bello
authors.forename: Mariza G
authors.initials: MG
authors.lastname: Morgado
authors.forename: Monick
authors.initials: M
authors.lastname: L Guimarães
mesh_terms: D000328:Adult; D001483:Base Sequence; D001938:Brazil / Q000453:epidemiology; D018791:CD4 Lymphocyte Count; D005260:Female; D014644:Genetic Variation; D015658:HIV Infections / Q000453:epidemiology* / Q000821:virology; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D020010:Heterosexuality / Q000706:statistics & numerical data; D018451:Homosexuality, Male / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D010802:Phylogeny; D015995:Prevalence; D011995:Recombination, Genetic; D012725:Sexual Behavior / Q000706:statistics & numerical data; D055815:Young Adult