XVIII International AIDS Conference

Abstract

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Evidence for the increase of HIV-1 C in the state of São Paulo, Brazil

R. Rodrigues1, L.F. Jamal2, V. Almeida3, T. Ragazzo3, J.L.P. Ferreira1, F. Carvalho1, D.L. Estevam2, R.D.B. Andrade1, L. Brigido1, Sao Paulo HIV Salvage Workgroup

1Instituto Adolfo Lutz, Virology, Sao Paulo, Brazil, 2Centro de Referencia DST/Aids de Sao Paulo, Sao Paulo, Brazil, 3Centro de Referencia DST/Aids de Campinas, Campinas, Brazil

Background: HIV-1 clade C is the most prevalent HIV-1 subtype in the AIDS pandemic. In the Americas clade C is rarely observed, with the exception of Southern Brazil were HIV-1 C and BC mosaics prevails in many cities. We evaluated the present and growth trends of HIV-1 C in Sao Paulo, a major core of the Brazilian epidemic.
Methods: Sequence from individuals failing ARV therapy was performed with Viroseq (2005-2007), Siemens (2008 ) kits or homemade nested PCR on retrotranscribed cDNA, resolved in a ABI 3100, the methodology used also for ARV naïve cases (2008-2009). Sequences were manually edited (Sequencher) and evaluated at NCBI and REGA. All non B and mosaics were further evaluated for by phylogeny with PAUP after model test. Simplot was used to evaluate recombinants and EPI6 to data management and statistics.
Results: Sequences from 1322 patients failing ARV therapy (2005-2008) and 230 naïve cases (2008-2009) were evaluated. Median age among treated individuals was 38 years, 34 among naïve. The proportion of clade C among treated patients by year of collection was 2005 (2/408,0.5%); 2006 (1/359,0.3%); 2007 (5/288,1.7%) and 2008 8/267,3%, p< 0.007). Among naïve cases, clade C at pol was observed 19/230(8.3%), significantly higher than among treated cases overall, and also when only cases from the same services are analyzed (p< 0.001). All pol C sequences formed a monophyletic cluster with other clade C Brazilian sequences with bootstrap over 70%, showing AA signatures common in southern Brazil clade C isolates. Additional Gag, Env and/or Integrase segments of 17 naïve pol C sequences revealed B fragments (BC recombination) in 47% of genomes.
Conclusions: The further spread of HIV-1 C to other areas of the country is expected and its trend, speed and potential to recombine should be monitored as it may change the epidemic dynamics.


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