Use of V3 loop peptide-specific antibody evaluation for subtyping HIV-1: Results of a vertical transmission study from Sao Paulo, Brazil

Plasma samples obtained from 97 children enrolled in a longitudinal study o f HIV-1 perinatal transmission in Sao Paulo, Brazil, were tested for the pr esence of specific V3-loop antibodies in order to determine the HIV-1 subty pe circulating among them. A set of seven synthetic peptides representative of the predominant HIV-1 subtypes detected in Brazil was employed in an in -house enzyme immunoassay (EIA) using two different protocols, one of which permits identification of high avidity antibodies (HAAb), Using these appr oaches we were able to detect antibodies in 64 out of 97 children, independ ently of the HIV-1 infection status, indicating the presence of subtype B i n all cases, except one, which could be considered to be of subtype F, Amon g subtype B cases, half of the samples reacted with the GWGR motif (type W is representative of Brazilian B strains), In the main, concordant results were obtained between peptide-EIA and HIV-1 status among infants, although in several cases of truly HIV-1 infected children, negative results could b e observed. Thirteen mother-child pairs and four fathers were also evaluate d, and the results confirmed subtype B to be the prevalent one among them, showing similar proportions of P and W types, Taken together, the results o btained identified subtype B (W and P) uniformly among adults and HIV-1 inf ected children from Sao Paulo, Brazil, and confirm vertical and sexual tran smission of the predominant strains.