An automated screening test for antibodies to human immunodeficiency virus-1

An automated pretransfusion testing system was applied to HIV antibody screening by a gelatin particle agglutination (HIV-PA) test. The test conditions for the test, such as diluent, plate shape, and incubation time, were applicable not only for the HIV-PA test but also for other routine tests, including those for hepatitis B surface antigen and HTLV-1 antibodies. After a 60-minute incubation, the plates were read automatically and then were assessed visually. Tests with seropositive samples obtained from hemophiliacs and an HIV enzyme immunoassay (EIA) familiarization panel showed that the automated HIV-PA test was more sensitive than the EIA and did not show a false-negative result. Of 11,300 blood donors, 44 were positive by the automated test, and 51 were positive by the EIA. None of the blood donors was confirmed to be seropositive. Using the automated test, a large number of samples could be screened in a relatively short time without a significant increase of nonspecific reactions.