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HIV-1 CRF02_AG is the most prevalent intersubtype recombinant form worldwide. Six HIV-1 samples from patients living in Rio de Janeiro, Brazil, were subtyped as CRF02_AG at the pol gene between 2004 and 2011. To trace the origin of these viruses, they were compared with 793 CRF02_AG pol sequences of African origin and another four Brazilian CRF02_AG pol sequences previously described. Phylogenetic analysis reveals that there have been at least four introductions of the CRF02_AG clade in Brazil, as signified by the presence of four phylogenetically distinct lineages, probably originated from western African countries (Benin, Ghana, and Guinea-Bissau). At least two CRF02_AG Brazilian lineages were successful in getting established and disseminated throughout the Rio de Janeiro state, with evidence of both horizontal and vertical transmission. Continuous epidemiological surveillance of HIV-1 strains circulating in Brazil is of paramount importance to the early detection of newly emerging viral lineages.

In the State of Rio de Janeiro, Brazil, HIV-1 diversity surveys have been performed mainly in the capital, and little is known about HIV-1 molecular epidemiology in small, inner cities. We studied 87 polymerase sequences recovered from 2 different studies conducted in inner cities of Rio de Janeiro State: a cross-sectional survey of patients receiving care in the small city of Santo Antonio de Pádua, and a case series of patients who were failing HAART in 26 additional inner cities throughout the State. Subtypes B (83.9%), F1 (8%), D (2.3%), and unique BF1 recombinants (5.7%) were demonstrated. The cross-sectional study found that 41.6% of the patients harbored genetically related strains that fell within clusters and probably took part in the same chain of viral spread. These clusters were phylogenetically unrelated to previously reported clusters from a neighboring city, suggesting that each small city harbors its own set of microepidemic lineages.

HIV-1 Subtype D occurs mainly in East and Central African countries, especially Uganda, where the prevalence of HIV-1 infection is among the highest in the world. We present the phylogenetic analysis of one nonautochthonous and four autochthonous (including a near full-length genome) Brazilian HIV-1 subtype D strains identified in Rio de Janeiro State, where subtypes B, F1, and BF1 recombinants predominate. Phylogenetic inferences using maximum likelihood were applied on a near-full length genome and on concatenated gag, protease, reverse transcriptase, integrase, C2V3/env, gp41, and nef segments. Sequences from an Angolan immigrant showed close genetic similarity with a strain described in Finland, from an HIV patient of African origin, whereas all four autochthonous Brazilian sequences clustered with South African strains, where subtype D occurs only in isolated cases. Our results suggest the successful introduction and circulation in Brazil of closely related HIV-1 subtype D strains, possibly of South African origin.