Abstract
BackgroundAlthough HIV-1 CRF12_BF and CRF38_BF are two epidemiologically important recombinant lineages circulating in Argentina and Uruguay, little is known about their population dynamics.MethodsA total of 120 "CRF12_BF-like" and 20 "CRF38_BF-like" pol recombinant sequences collected in Argentina and Uruguay from 1997 to 2009 were subjected to phylogenetic and Bayesian coalescent-based analyses to estimate evolutionary and demographic parameters.ResultsPhylogenetic analyses revealed that CRF12_BF viruses from Argentina and Uruguay constitute a single epidemic with multiple genetic exchanges among countries; whereas circulation of the CRF38_BF seems to be confined to Uruguay. The mean estimated substitution rate of CRF12_BF at pol gene (2.5 × 10-3 substitutions/site/year) was similar to that previously described for subtype B. According to our estimates, CRF12_BF and CRF38_BF originated at 1983 (1978-1988) and 1986 (1981-1990), respectively. After their emergence, the CRF12_BF and CRF38_BF epidemics seem to have experienced a period of rapid expansion with initial growth rates of around 1.2 year-1 and 0.9 year-1, respectively. Later, the rate of spread of these CRFs_BF seems to have slowed down since the mid-1990s.ConclusionsOur results suggest that CRF12_BF and CRF38_BF viruses were generated during the 1980s, shortly after the estimated introduction of subtype F1 in South America (~1975-1980). After an initial phase of fast exponential expansion, the rate of spread of both CRFs_BF epidemics seems to have slowed down, thereby following a demographic pattern that resembles those previously reported for the HIV-1 epidemics in Brazil, USA, and Western Europe.
Highlights
HIV-1 CRF12_BF and CRF38_BF are two epidemiologically important recombinant lineages circulating in Argentina and Uruguay, little is known about their population dynamics
The AIDS epidemic in South America is caused by multiple HIV-1 group M subtypes including subtypes B, F1, and C, in addition to BF1 and BC recombinant forms
Previous studies performed by our group suggest that the HIV-1 subtype F1 and BF1 epidemics in South America were initiated after the introduction of a single F1 strain into Brazil between the middle and late 1970s [22,23,24]
Summary
HIV-1 CRF12_BF and CRF38_BF are two epidemiologically important recombinant lineages circulating in Argentina and Uruguay, little is known about their population dynamics. Previous studies performed by our group suggest that the HIV-1 subtype F1 and BF1 epidemics in South America were initiated after the introduction of a single F1 strain into Brazil between the middle and late 1970s [22,23,24]. After its introduction, this founder subtype F1 strain probably recombined with the local subtype B virus generating the large diversity of CRFs_BF1 and URFs_BF1 currently observed in the continent [24]. Based on monophyletic clustering and coincident recombination breakpoints, it was suggested that most BF1 recombinants circulating in Argentina and Uruguay derived from a common recombinant ancestor [21,24,25]
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