Diagnosis of perinatally acquired HIV-1 infection using an IgA ELISA test

The clinical utility of the detection of anti-HIV-1 IgA antibodies using a modified commercial ELISA (EIA) test for the early diagnosis of perinatally acquired HIV-1 infection was evaluated. One hundred and seventeen sera were obtained from 86 infants born to HIV-1-infected mothers and tested for HIV IgA antibodies by an ELISA test (third generation) after removal of IgG with recombinant protein G. Infants were classified according to the Center for Disease Control and Prevention's (CDC) classification system after 15 months of age; 46 were classified as HIV-infected children and 40 as uninfected. HIV-IgA antibodies were detected in 53 of 64 serum samples from all infected children. No significant differences were observed in IgA detection among symptomatic or asymptomatic infected children. However, when analyzed by age a significant difference was observed in IgA detection when children who were over 6 months of age were compared with the younger group (Fisher exact test, p = 0.0000053). All 53 samples from 40 noninfected children were IgA-negative. Statistical analysis was assessed comparing IgA results with HIV infection status as the gold standard. Sensitivity (95%) and specificity (100%), positive predictive value (100%), and negative predictive value (94%) of IgA antibody determination were analyzed taking into account only one sample per child and only children older than 6 months. Positive likelihood ratio was 95.9% and negative likelihood ratio was 94%. Test efficiency was 97%. The detection of IgA HIV antibodies using EIA is an effective method for early diagnosis of HIV-infected infants in comparison with conventional IgG HIV antibody tests. It is a simple and inexpensive method that could be used in both developed and developing countries.