The subtype C accounts for >50% of HIV type 1 (HIV-1) infections worldwide and it is currently the predominant viral form in South Brazil. Subtype C has been reported in all Brazilian regions; however, the phylogenetic relationship among strains circulating in those regions still remains unclear. This study aimed to investigate the origin and dynamic dispersion of HIV-1 subtype C toward Northeast Brazil. Our phylogenetic analysis suggests that most subtype C strains circulating in Brazil (99%) are descendant from the main lineage whose entrance in the country was previously described in the 1970s. According to the literature, additional introductions of subtype C were reported in the country through the Southeast region and in this study we identified another entry event that occurred most likely through the North region. Furthermore, our analysis suggests that the spread of subtype C to Brazilian Northeastern states occurred through multiple independent introductions of the main lineage that originated in South Brazil between mid-1980s and late 1990s. Despite the observation of eventual new HIV-1 subtype C introductions, our results highlight the predominance of a single lineage of this subtype in Brazil and the importance of South region in its dissemination throughout the country.
Keywords: Brazil; HIV-1; Northeast; subtype C.