Patterns of anti-HIV IgG3, IgA and p24Ag in perinatally HIV-1 infected infants.

The antibody patterns of HIV-1 IgG3, IgG and IgA and of HIV-1 p24 antigen were investigated in Thai infants born to mothers infected with HIV-1. In the 17 HIV-1 infected infants, anti-HIV antibodies were detected continuously over a period of 15-18 months and a high level of specific IgG3 subclass was observed. Anti-HIV IgA could be detected at 6 months of age whereas p24Ag was detected at 2 months. In 79 uninfected infants, maternal anti-HIV IgG gradually decreased over 9 months whilst specific IgG3 decayed rapidly during the first 6 months. Both p24Ag and anti-HIV IgA were not found in these uninfected infants. Thus, the disappearance of anti-IgG3 subclass antibodies within 6 months can predict whether infants are uninfected whereas the persistence of anti-HIV IgG and IgG3 subclass antibodies, the production of anti-HIV IgA antibody and the presence of p24Ag appear as an adjunct to the diagnosis of HIV vertical transmission. The necessary assays are relatively simple and could be performed individually.