Molecular and biological diversity of HIV-1 in Brazil

Identification of two HIV type 1 circulating recombinant forms in Brazil

Recombination is an important way to generate genetic diversity. Accumulation of HIV-1 full-length genomes in databases demonstrated that recombination is pervasive in viral strains collected globally. Recombinant forms achieving epidemiological relevance are termed circulating recombinant forms (CRFs). CRF12_BF was up to now the only CRF described in South America. The objective was to identify the first CRF in Brazil conducting full genome analysis of samples sharing the same partial genome recombinant structure. Ten samples obtained from individuals residing in Santos, Brazil, sharing the same recombination pattern based on partial genome sequence data, were selected from a larger group to undergo full length genome analysis. Near full length genomes were assembled from overlapping fragments. Mosaic genomes were evaluated by Bootscan, alignment inspection, and phylogenetic analysis using neighbor joining and maximum likelihood. Full genomes were also analyzed by split decomposition. We were able to identify five mosaic genomes. Two of these structures were represented by at least three samples derived from epidemiologically unlinked individuals. These structures were named CRF28_BF and CRF29_BF and are the second and third CRFs composed exclusively by subtypes B and F as well as the second and third CRFs encountered in South America. Other recombinant forms studied here resembled CRF28_BF and CRF29_BF. Our results suggest that a diverse population of related recombinants, including CRFs may play an important part in the Brazilian and South American epidemic.

Molecular epidemiology of HIV-1 in Rio Grande, RS, Brazil

We conducted a molecular epidemiological study to investigate HIV-1 strains in Rio Grande, southern Brazil, searching for an association with transmission mode and risk behavior. Patients (185) identified at an AIDS treatment reference Hospital, from 1994 to 1997, were included; from which 107 blood samples were obtained. Nested PCR was realized once for each sample; for amplified samples (69) HIV subtypes were classified using the heteroduplex mobility assay. Subtypes identified were B (75%), C (22%) and F (3%). All infections with C were diagnosed after 1994. Comparing patients with B and C, no differences were detected regarding demographic, clinical and laboratory characteristics; survival analysis did not reveal differences in HIV to AIDS evolution. A higher proportion of injecting drug users, IDU (not significant, p < .07) was found among those with C. This suggests that C may have been introduced in this area through IDU, and is being spread, probably by their sexual partners, to persons with other risk practices.

Genetic and antigenic variability of HIV type 1 in Brazil

Six Brazilian strains of human immunodeficiency virus type 1 (HIV-1) were isolated from infected individuals residing in different regions of Brazil between 1987 and 1989. Phylogenetic analysis based on an 860-base pair env fragment, including V3, V4, V5, and the beginning of gp41, classified the Brazilian strains significantly in genotype B, with interhost distances between 5.9 and 13.1% (mean value, 10%). Amino acid sequence analysis of the V3 loop revealed that three strains contained the North American/European GPGR motif as the tip of the loop whereas in the other three strains proline (P) was substituted by tryptophan (W), methionine (M), or phenylalanine (F). A consensus peptide, Bra-cons, was designed containing GWGR as the tip of the loop. Serological reactivity to the Bra-cons peptide and other V3 peptides (MN, SF2, HBX2, RF, MAL, ELI, Z6, and a Côte d'Ivoire peptide, CI-cons) was compared for 114 HIV-1-positive sera from Rio de Janeiro. Sixty-nine sera (60.5%) reacted with peptides belonging to genotype B, of which 10 sera also reacted with peptides belonging to genotype A (n = 7) and D (n = 3). Eighteen sera (15.8%) had binding antibodies to the Bra-cons peptide. A high number of sera (n = 43; 37.7%) had no antibodies to any of the V3 peptides tested. This result suggests that HIV-1 variants with aberrant V3 loops may circulate in Rio de Janeiro.