Semiquantitative human immunodeficiency virus antibody tests in diagnosis of vertical infection

Abstract

Objective. This study evaluated the roles of semiquantitative anti-HIV antibody tests for early diagnosis of vertical HIV-1 infection in infants. Methods. The study included 0- to 18-month-old children of HIV-1-infected mothers. They were regularly followed up, and blood was obtained for semiquantitative anti-HIV tests using a particle agglutination (PA) test and a microparticle enzyme immunoassay (MEIA). Results. One hundred forty-six children of HIV-1-infected mothers, including 104 infected and 42 uninfected infants, were studied. Using anti-HIV titer of ≤1:100 by PA and optical values of ≤3 by MEIA for diagnosis of not being infected, ~69 and 53% of the uninfected cases at age 7 to 8 months, 76 and 67% at age 9 months and 100% at age 12 months could be diagnosed. By comparison with the diagnosis by qualitative tests the figures were 16%, 8 and 11%, 70 and 74% at the same ages. All asymptomatic HIV-infected cases had persistently high PA titers and MEIA values of at least 1:5000 and 6, respectively, but 7 cases with AIDS-related manifestation at the time of tests had low anti-HIV titers. One severely ill, HIV-infected infant had a transient negative anti-HIV test at the age of 7 months. Two asymptomatic infected children, who had been breast-fed, had transient decrease in anti-HIV titers after the age of 6 months, and transient seroreversion occurred in one. Conclusion. Semiquantitative anti-HIV tests between the age of 6 to 12 months were very useful in diagnosis of HIV-1 infection in infants born of HIV-1-infected mothers. Interpretation must be accompanied by information about AIDS-related manifestation and history of breast-feeding.