Diversity of HIV-1 Subtype B: Implications to the Origin of BF Recombinants

Autor(es)

Leal, Elcio ^[1] ; Villanova, Fabiola E. ^[1]

Afiliação do(s) autor(es)

^[1] Fed Univ Para, BR-66059 Belem, Para - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PLoS One; v. 5, n. 7, p. e11833, 2010.
• Citações Web of Science: 15

Resumo

Background: The HIV-1 subtype B epidemic in Brazil is peculiar because of the high frequency of isolates having the GWGR tetramer at V3 loop region. It has been suggested that GWGR is a distinct variant and less pathogenic than other subtype B isolates. Methodology/Principal Findings: Ninety-four percent of the HIV-1 subtype B worldwide sequences (7689/8131) obtained from the Los Alamos HIV database contain proline at the tetramer of the V3 loop of the env gene (GPGR) and only 0.74% (60/8131) have tryptophan (GWGR). By contrast, 48.4% (161/333) of subtype B isolates from Brazil have proline, 30.6% (102/333) contain tryptophan and 10.5% (35/333) have phenylalanine (F) at the second position of the V3 loop tip. The proportion of tryptophan and phenylalanine in Brazilian isolates is much higher than in worldwide subtype B sequences (chi-square test, p = 0.0001). The combined proportion of proline, tryptophan and phenylalanine (GPGR+GWGR+GFGR) of Brazilian isolates corresponds to 89% of all amino acids in the V3 loop. Phylogenetic analysis revealed that almost all subtype B isolates in Brazil have a common origin regardless of their motif (GWGR, GPGR, GGGR, etc.) at the V3 tetramer. This shared ancestral origin was also observed in CRF28_BF and CRF29_BF in a genome region (free of recombination) derived from parental subtype B. These results imply that tryptophan substitution (e.g., GWGR-to-GxGR), which was previously associated with the change in the coreceptor usage within the host, also occurs at the population level. Conclusions/Significance: Based on the current findings and previous study showing that tryptophan and phenylalanine in the V3 loop are related with coreceptor usage, we propose that tryptophan and phenylalanine in subtype B isolates in Brazil are kept by selective mechanisms due to the distinct coreceptor preferences in target cells of GWGR, GFGR and GFGR viruses. (AU)

• Processo FAPESP: 07/52841-8 - Análise bayesiana de aspectos filogenética e seletivos do HIV-1 na epidemia brasileira
• Beneficiário: Elcio de Souza Leal
• Modalidade de apoio: Bolsas no Exterior - Pesquisa