HIV-1 subtypes among intravenous drug users from two neighboring cities in São Paulo State, Brazil.

In order to assess the molecular epidemiology of HIV-1 in two neighboring cities located near the epicenter of the HIV-1 epidemics in Brazil (Santos and São Paulo), we investigated 83 HIV-1 strains obtained from samples collected in 1995 from intravenous drug users. The V3 through V5 region of the envelope of gp 120 was analyzed by heteroduplex mobility analysis. Of the 95 samples, 12 (12.6%) were PCR negative (6 samples from each group); low DNA concentration was the reason for non-amplification in half of these cases. Of the 42 typed cases from São Paulo, 34 (81%, 95% confidence limits 74.9 to 87.0%) were B and 8 (19%, 95% confidence limits 12.9 to 25.0%) were F, whereas of the 41 typed cases from Santos, 39 (95%, 95% confidence limits 91.6 to 98.4%) were B and 2 (5%, 95% confidence limits 1.6 to 8.4%) were C. We therefore confirm the relationship between clade F and intravenous drug use in São Paulo, and the presence of clade C in Santos. The fact that different genetic subtypes of HIV-1 are co-circulating indicates a need for continuous surveillance for these subtypes as well as for recombinant viruses in Brazil.

HIV-1 subtypes among intravenous drug users from two neighboring cities in São Paulo State, Brazil

In order to assess the molecular epidemiology of HIV-1 in two neighboring cities located near the epicenter of the HIV-1 epidemics in Brazil (Santos and São Paulo), we investigated 83 HIV-1 strains obtained from samples collected in 1995 from intravenous drug users. The V3 through V5 region of the envelope of gp 120 was analyzed by heteroduplex mobility analysis. Of the 95 samples, 12 (12.6 percent) were PCR negative (6 samples from each group); low DNA concentration was the reason for non-amplification in half of these cases. Of the 42 typed cases from São Paulo, 34 (81 percent, 95 percent confidence limits 74.9 to 87.0 percent) were B and 8 (19 percent, 95 percent confidence limits 12.9 to 25.0 percent) were F, whereas of the 41 typed cases from Santos, 39 (95 percent, 95 percent confidence limits 91.6 to 98.4 percent) were B and 2 (5 percent, 95 percent confidence limits 1.6 to 8.4 percent) were C. We therefore confirm the relationship between clade F and intravenous drug use in São Paulo, and the presence of clade C in Santos. The fact that different genetic subtypes of HIV-1 are co-circulating indicates a need for continuous surveillance for these subtypes as well as for recombinant viruses in Brazil

HIV-1 diversity in Brazil: genetic, biologic, and immunologic characterization of HIV-1 strains in three potential HIV vaccine evaluation sites. Brazilian Network for HIV Isolation and Characterization.

The Brazilian Network for HIV Isolation and Characterization was established for the surveillance of HIV variability in Brazil. Here, we report characterization of HIV strains and virus-specific immune responses from 35 clinical samples collected from three potential HIV vaccine sites. Three genetic subtypes of HIV-1 were identified by heteroduplex mobility assay (HMA) B (in 82.9% of the samples), F (14.3%), and C (2.9%). Phylogenetic analysis based on the C2V3/env DNA sequence from all 25 specimens examined was 100% concordant with HMA results. Four variants of subtype B with different tetrapeptides at the tip of the V3 loop were found: the GPGR motif (North American), GWGR motif (Brazilian B"), and two minor variants, GFGR and GPGS, as previously detected. No significant association was found between HIV-1 subtypes and the mode of transmission or biologic properties of HIV-1 isolates (derived from 88.6% of the specimens). Only 5 of 16 isolates studied were neutralized by the autologous sera. Consistent with previous results, no relation between viral subtype and peptide enzyme-linked immunosorbent assay (ELISA) seroreactivity or neutralization was evident. This study also demonstrated the effectiveness of the collaborative approach followed by Brazilian scientists when addressing a complex subject such as HIV variability.