IMMUNE COMPLEX-DISSOCIATED P24 ANTIGEN IN CONGENITAL OR PERINATAL HIV-INFECTION - ROLE IN THE DIAGNOSIS AND ASSESSMENT OF RISK OF INFECTIONIN INFANTS

Immune complex-dissociated (ICD) HIV-1 p24 antigen assay is a rapid te chnique for assessing the presence of HIV gag or core protein in plasm a or serum. In this study, ICD p24 antigen detection in HIV-1 infected mothers and their infants enrolled in the Women and Infants Transmiss ion Study (WITS) was evaluated primarily as a diagnostic assay for HIV -1 detection in young infants and for its association with perinatal t ransmission. Plasma from 47 infected infants and 160 uninfected infant s was examined, along with plasma from 197 of their mothers who had a delivery or close-to-delivery specimen. ICD p24 antigen was detected i n plasma of 27.3% of infected infants at birth and in 70% to 81% at 1 to 6 months. The diagnostic specificity at birth was 90% and 98% to 10 0.0% at 1 to 6 months. The ICD p24 antigen concentration correlated wi th concurrent quantitative HIV culture results. The risk of transmissi on from mother to infant was higher if the mother had detectable ICD p 24 antigen at or near the time of delivery (p = 0.002), but its presen ce did not accurately predict transmission (positive predictive value of 36%, negative predictive values of 85%). The relative ease of perfo rming the ICD p24 antigen assay and the low cost compared with that of HIV culture or DNA PCR makes this test a useful adjunct for the diagn osis of perinatal HIV infection and for enhancing understanding of its pathogenesis, particularly where cost and availability limit access t o more sensitive assays.