V3 Region Polymorphisms in HIV-1 from Brazil: Prevalence of Subtype B Strains Divergent from North American/European Prototype and Detection of Subtype F

Abstract

Viral DNA sequences were determined over the V3 region of env from 28 infected individuals living in the high HIV-1 prevalence Brazilian cities of Rio de Janeiro and São Paulo. Twenty-six belonged to envelope sequence subtype B, prevalent in North America and Europe, and one was classified as subtype F, found recently in Brazil and in Romania (one appeared to be a B/F recombinant). Octameric sequences at the tip of the subtype B V3 loops were variable and distinct from those prevalent in North America and Europe. The GPGR motif, prevalent in North American/European strains, was found in only 8 (28.5%) sequences, whereas GWGR was found in 12 (43%) and novel sequences in 8 (28.5%). Brazilian subtype B sequences also diverged from the consensus North American/European strains over the remainder of the V3 loop. These results suggest that Brazilian HIV-1 B strains may have important antigenic differences from prototype subtype B strains currently being evaluated for use in HIV vaccines. These results should be taken into account for future vaccine programs in Brazil.

Genetic variability of HIV-1 isolates from Minas Gerais, Brazil

“…In nine of eleven env amino acid sequences, the tetrameric subdomain at the crown of V3 loop (Table 1) had the sequence GPGR, including the B/F isolate (BHGM19, blood donor, heterosexual transmission), whose crown had the sequence HIGPGRAF, identical to previously described and independently collected F subtype isolates from other cities in Brazil (3,5). One isolate (JS, hemophiliac patient) had the GPGQ sequence, which is common in subtypes A, C and E isolates and one (JMR, heterosexual transmission) had the sequence GPGK, rarely reported in subtype B.…”

Serotyping HIV-1 with V3 peptides: detection of high avidity antibodies presenting clade-specific reactivity

“…Different genotypes may have evolved by mutations in regions other than those that determine epitopes for antibody responses, resulting in an overestimation of antigenic differences by genetic classification. Conversely, real antigenic differences within genotypically defined subgroups may also exist, as in the case of two antigenically distinct strains of subtype B present in Brazil (7,12). It has been reported that subtypes A and D show high levels of intrasubtype variability (19).…”

“…The immunodominant 15-amino acid region of V3 was determined in previous experiments using an overlapping V3 peptide set derived from the MN strain of HIV-1 (data not shown). The Brazilian BR2 peptide shown in Figure 1 represents a consensus sequence of one of the two genetic and antigenic subtype B variants that co-circulate in Brazil (7). The use of avidinbiotin interaction improves the antigen conformation in the well, allowing a tighter antibody binding to the peptide (data not shown).…”

“…Most of these studies have used synthetic peptides representing the hypervariable V3 region of the HIV-1 envelope. Unfortunately, HIV-1 subtypes present broad cross-reactivity when this approach is used (4,6,7).…”

Techniques used to identify the Brazilian variant of HIV-1 subtype B

“…The current Brazilian HIV/AIDS epidemic is mainly caused by subtype B; however, the existence of a small proportion of other subtypes such as F, C, B/C, and B/F has been consistently described (1,2). Several studies have reported the existence of a Brazilian subtype B variant designated as subtype B" (3)(4)(5)(6)(7)(8)(9)(10).…”