Evolutionary Dynamics of HIV-1 BF and CB Recombinants and Its Parental Counterparts in South America

Analysis of the near full-length genomes revealed that the subtype F appeared in Brazilian HIV-1 epidemics at least 10 years after the subtype B. Notably, the BF recombinant emerged almost simultaneously with the introduction of subtype F in Brazil. Analysis of reverse transcriptase fragments indicated that the C subtype originated in the early 1990s, and the CB recombinant emerged 2 years after the appearance of subtype C. The high growth rate of BF recombinant possibly obscured the prevalence of the pure subtype F. In contrast, subtype C, although appearing 20 years after subtype B, was responsible for a well-defined epidemic. Nevertheless, the CB recombinant equally emerged rapidly after the introduction of the second parental (subtype C). Our results suggest that the outcome related to the recombinant profile are probably influenced by the capacity of the newly arriving subtype to establish a critical number of infections before it recombines with the previous circulating subtype.