RESUMEN
BACKGROUND: Although 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. METHODS: A 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. RESULTS: Phylogenetic 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 x 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. CONCLUSIONS: Our 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.
Asunto(s)
Infecciones por VIH/epidemiología , Infecciones por VIH/virología , VIH-1/clasificación , VIH-1/genética , Recombinación Genética , Adulto , Argentina/epidemiología , Niño , Preescolar , Análisis por Conglomerados , Genotipo , VIH-1/aislamiento & purificación , Humanos , Epidemiología Molecular , Filogenia , Mutación Puntual , Análisis de Secuencia de ADN , Homología de Secuencia , Uruguay/epidemiología , Adulto Joven , Productos del Gen pol del Virus de la Inmunodeficiencia Humana/genéticaRESUMEN
Recombination has been shown to be an important force in HIV-1 evolution. Recombination contributes to an increase in genetic variation and hinders vaccine design efforts. Several molecular epidemiology studies in South America described the circulation of subtypes B, F, and C as well as several B/F1 recombinants. This study performed by nucleotide sequencing in at least two genes of 89 samples from Uruguay has shown a complex HIV-1 epidemic characterized by the cocirculation of subtype B, and subtype C strains, together with an important group of BF1 recombinant viruses, including isolates similar to CRF12_BF. In addition we identified a new circulating recombinant form, designated CRF38_BF(1), which was dominant in the recombinant virus group.
Asunto(s)
Infecciones por VIH/virología , VIH-1/clasificación , VIH-1/aislamiento & purificación , Análisis por Conglomerados , Genotipo , VIH-1/genética , Humanos , Datos de Secuencia Molecular , Filogenia , Recombinación Genética , Análisis de Secuencia de ADN , Homología de Secuencia , UruguayRESUMEN
The first molecular epidemiology study of human immunodeficiency virus type 1 (HIV-1) in Panama has been performed with plasma samples from 66 AIDS patients infected by different transmission routes and obtained from distinct locations. All samples were amplified by RT-PCR and sequenced in gag (p17) and env (C2-C4) genes. Phylogenetic analyses revealed that 64 (97%) of the samples belong to subtype B. We also identified the presence of two CRF, one CRF12_BF and one CRF02_AG. The most notable feature of the subtype B epidemic in Panama was the large genetic distance among isolates with a mean of 15.2% but reaching up to 31.3 % in env, indicating an epidemic with a long period of evolution.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/epidemiología , Síndrome de Inmunodeficiencia Adquirida/virología , VIH-1/clasificación , VIH-1/genética , Adulto , Anciano , Análisis por Conglomerados , Femenino , Genotipo , VIH-1/aislamiento & purificación , Humanos , Masculino , Persona de Mediana Edad , Epidemiología Molecular , Datos de Secuencia Molecular , Panamá/epidemiología , Filogenia , Plasma/virología , ARN Viral/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN , Homología de Secuencia , Productos del Gen env del Virus de la Inmunodeficiencia Humana/genética , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/genéticaRESUMEN
The objective of the present study was to determine if natural suppression of plasma viremia below the detection limit of commercial assays (50-80 copies HIV-1 RNA/ml) can contain the HIV-1 evolution. HIV-1 quasispecies complexity in PBMC DNA was assessed in the env gene at two time points in 14 long-term nonprogressors (LTNPs). Sequence changes consistent with viral evolution was found in all patients with a median plasma RNA viral load >100 copies/ml. Evidence of low-level viral evolution was detected in two of four patients with intermittent viremia and a median plasma HIV-1 RNA load of >80 copies/ml. No significant evolution was observed in the three LTNPs with persistent viral suppression below the detection limit. Overall, a significant positive correlation (p < 0.001) was observed between viral evolution and plasma RNA viral load in the LTNPs analyzed. These results suggest that the detection limit of ultrasensitive viremia assays could represent an important threshold below which intrahost HIV-1 evolution does not occur.
Asunto(s)
Genes env , Infecciones por VIH/virología , Sobrevivientes de VIH a Largo Plazo , VIH-1/genética , Adolescente , Adulto , Anciano , Terapia Antirretroviral Altamente Activa , Niño , Preescolar , Evolución Molecular , Femenino , VIH-1/fisiología , Humanos , Masculino , Persona de Mediana Edad , Filogenia , ARN Viral/sangre , Carga Viral , Viremia/virologíaRESUMEN
To help in the vaccine development, WHO-UNAIDS launched a program for the isolation and characterization of subtype C viruses, the most prevalent HIV-1 subtype in the world. Isolates were obtained from Brazil, China, India, Israel, and South Africa, countries in which these strains are circulating. In this study we genetically characterized a set of samples displaying the culture-negative phenotype by sequencing the nucleotides of three genomic regions: the p17 region of the gag gene, the C2V3C3 fragment of the env gene, and the nef gene. The association of the culture-negative phenotype with the nef gene was studied, and we found a significant accumulation of gene alterations. Except for one B/C recombinant from India, the samples studied formed a monophylogenetic subtype C clade, although samples from Brazil formed a statistically significant, independent subcluster in two of the three genes analyzed.