Rapid Serologic Testing with Immune-Complex-Dissociated HIV p24 Antigen for Early Detection of HIV Infection in Neonates

Background Serologic detection of human immunodeficiency virus (HIV) infection in neonates is complicated by the presence of immune complexes, consisting of passively transferred maternal antibodies and HIV antigens. A new, rapid assay has been designed to disrupt these immune complexes in order to permit the detection of a specific HIV antigen. We evaluated the efficacy of this assay in detecting HIV infection in neonates. Methods We measured p24 antigen in blood samples from both infected and uninfected children of HIV-infected mothers. The samples were treated with glycine hydrochloride to dissociate the immune complexes, followed by neutralization with TRIS-hydrochloric acid. A commercial HIV p24 antigen assay was then used, with an optical density greater than 0.120 at a wavelength of 450 nm defined as indicating a positive result. Results Of eight cord-blood samples from neonates with proved HIV infection, five were positive for immune-complex-dissociated p24 antigen. For two other neonates the firs...