title: A specific subtype C of human immunodeficiency virus type 1 circulates in Brazil.
abstract: OBJECTIVE
  To characterize the subtype C strains of HIV type 1 that circulate in Brazil, especially those originated from the southern part of the country.
  
  
  METHODS
  One hundred and twelve HIV-1-positive subjects had their plasma viral RNA extracted. Protease (PR) and reverse transcriptase (RT) genomic regions were polymerase chain reaction-amplified and sequenced for subtype determination. Subtype C strains were selected and compared to other strains of this subtype from the database, and specific amino acid signature patterns were searched.
  
  
  RESULTS
  Brazilian subtype C viruses form a very strong monophyletic group when compared to subtype C viruses from other countries and presented specific signature amino acids. Recombinants between subtype C and B viruses have been documented in areas of co-circulation. The incidence of primary PR and RT inhibitor resistance mutations in drug-naïve subjects was observed. An increasing number of secondary resistance mutations was also seen, some of which are characteristic of subtype C-related sequences.
  
  
  CONCLUSIONS
  Introduction of subtype C of HIV-1 in Brazil was likely a single event of one or a mixture of similarly related strains. Recombination between subtype C and B viruses is an ongoing process in the country. Primary and secondary drug resistance mutations were observed, although some of the secondary mutations could be associated with subtype C molecular signatures. Subtype-specific polymorphisms of PR and RT sequences found in this subtype C Brazilian variant might influence this emergence and have an impact on HIV treatment and on vaccine development in the country.
authors.affiliation: Laboratório de Virologia Molecular, Departamento de Genética, Universidade Federal do Rio de Janeiro, CCS - Bloco A - Cidade Universitária - Ilha do Fundão, 21944-970 Rio de Janeiro, RJ, Brazil.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Soares
authors.forename: Tulio
authors.initials: T
authors.lastname: De Oliveira
authors.forename: Rodrigo M
authors.initials: RM
authors.lastname: Brindeiro
authors.forename: Ricardo S
authors.initials: RS
authors.lastname: Diaz
authors.forename: Ester C
authors.initials: EC
authors.lastname: Sabino
authors.forename: Luís
authors.initials: L
authors.lastname: Brigido
authors.forename: Ivone L
authors.initials: IL
authors.lastname: Pires
authors.forename: Mariza G
authors.initials: MG
authors.lastname: Morgado
authors.forename: Maria C
authors.initials: MC
authors.lastname: Dantas
authors.forename: Draurio
authors.initials: D
authors.lastname: Barreira
authors.forename: Paulo R
authors.initials: PR
authors.lastname: Teixeira
authors.forename: Sharon
authors.initials: S
authors.lastname: Cassol
authors.forename: Amilcar
authors.initials: A
authors.lastname: Tanuri
mesh_terms: D000293:Adolescent; D000328:Adult; D000349:Africa; D000595:Amino Acid Sequence; D001938:Brazil / Q000453:epidemiology; D024882:Drug Resistance, Viral / Q000235:genetics; D005260:Female; D014644:Genetic Variation; D015658:HIV Infections / Q000453:epidemiology / Q000821:virology*; D016333:HIV Protease / Q000235:genetics; D054303:HIV Reverse Transcriptase / Q000235:genetics; D015497:HIV-1 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012367:RNA, Viral / Q000302:isolation & purification; D014773:Virology / Q000379:methods
chemical_list: D012367:RNA, Viral; D054303:HIV Reverse Transcriptase; D016333:HIV Protease