Increasing heterosexual transmission of HIV-1 subtype C in Inland Central Western Brazil

Abstract

The molecular epidemiology of HIV-1 in Brazil is complex and heterogeneous because several subtypes co-circulate with some important regional differences. This study evaluated HIV-1 subtypes amongst pregnant women living in the metropolitan area and in the interior cities from central western Brazil. From June 2008 to June 2010, 86.9% of confirmed cases of HIV-1 infection amongst pregnant women (172 out of 198 cases) were recruited in Goiania/Goias state. The HIV-1 pol gene was sequenced after nested-PCR. HIV-1 subtypes were assigned by REGA, phylogenetic, and bootscan analyses. The median age of participants was 26 years (15-41 years range); 58.7% of participants were diagnosed during prenatal care and 51.7% of participants came from >50 interior cities within Goias state. Amongst the 131 HIV-1 pol sequences, 64.9% were subtype B, 13.0% were BF1 recombinant, 11.4% were subtype C, 7.6% were subtype F1, and 2.3% were BC recombinant. According to the HIV-1 diagnosis date (1994-2010), a significant increase in subtype C and a decrease of BF1 mosaics were observed over time. All subtype C patients lived in interior cities where the highest prevalence of subtype C outside southern Brazil was observed (18.4%). Phylogenetic analysis revealed multiple independent introductions of the Brazilian subtype C clade from the southern/southeastern regions of Brazil. The HIV-1 epidemic in women from central western Brazil infected by the heterosexual route is characterized by an unexpectedly high prevalence of subtype C viruses highly related to those circulating in southern/southeastern Brazil. These findings highlight the importance of molecular surveillance programs outside large metropolitan regions in Brazil.