IMPROVED SPECIFICITY OF IN-VITRO ANTI-HIV ANTIBODY-PRODUCTION - IMPLICATIONS FOR DIAGNOSIS AND TIMING OF TRANSMISSION IN INFANTS BORN TO HIV-SEROPOSITIVE MOTHERS

In vitro anti-HIV antibody production (IVAP), initially introduced as a method for diagnosis of human immunodeficiency virus type 1 (HIV-1) infection in infants, has been limited in its application because of p oor specificity and sensitivity early in life. The aims of this study were to improve the specificity of the IVAP assay and to evaluate its sensitivity in conjunction with assays of HIV culture, polymerase chai n reaction (PCR), and p24 antigen. To prevent false-positive reactions resulting from maternal serum-derived cytophilic anti-HIV IgG, additi onal preculture and washing steps for peripheral blood mononuclear cel ls (PBMCs) were introduced that resulted in dramatic improvement in sp ecificity of IVAP. The sensitivity of the revised IVAP at age <3 month s in 20 infected infants was, however, only 25%; of 15 infected infant s initially negative in IVAP, 13 became positive at a mean estimated a ge of 4.4 +/- 1.8 months. When correlated with virological assays, a f ailure to respond in IVAP at age <1 month was often associated with ne gative virological identification, whereas a positive IVAP response at age <3 months was always associated with positive results in all viro logical assays. Moreover, conversion from negative IVAP to positive re sponses occurred subsequent to, and not concurrently with, a positive virological identification of infected infants. The revised IVAP metho dology renders this assay potentially useful as an additional tool not only for the diagnosis of HIV infection, but for estimating timing of maternal-infant HIV transmission as well