A specific subtype C of human immunodeficiency virus type 1 circulates in Brazil

Objective: To characterize the subtype C strains of HIV type I that circulate in Brazil, especially those originated from the southern part of the country.Design and 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-naive 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. (C) 2003 Lippincott Williams Wilkins.Univ Fed Rio de Janeiro, Dept Genet, Mol Virol Lab, Ilha Fdn, BR-21944970 Rio de Janeiro, BrazilUniv Natal, Nelson Mandela Sch Med, Africa Ctr, HIV Mol Virol & Bioinformat Unit 1, ZA-4001 Durban, South AfricaUNIFESP, Escola Paulista Med, Lab Retrovirol, São Paulo, BrazilUniv São Paulo, Hemoctr São Paulo, Fdn Prosangue, São Paulo, BrazilInst Adolfo Lutz Registro, Lab Retrovirol, São Paulo, BrazilInst Biol Exercito, Virol Lab, Rio de Janeiro, BrazilFdn Inst Oswaldo Cruz, Dept Imunol, BR-20001 Rio de Janeiro, BrazilMinist Saude, CN DST AIDS, Brasilia, DF, BrazilUNIFESP, Escola Paulista Med, Lab Retrovirol, São Paulo, BrazilWeb of Scienc