Performance and cost-effectiveness of a dual rapid assay system for screening and confirmation of human immunodeficiency virus type 1 seropositivity.

Recent studies have shown that rapid, instrument-free assays for the detection of antibody to human immunodeficiency virus (HIV) can be as sensitive and specific as enzyme-linked immunosorbent assay (ELISA) for screening of donated blood in developing countries. Currently, however, specimens which test positive on a screening assay must still be confirmed by Western blot (immunoblot), a method which is not feasible in most developing-country laboratories. We examined whether a testing hierarchy which utilizes neither conventional ELISA nor Western blot can be reliably used for screening and confirmation of HIV infection in a high-risk population. In a retrospective analysis of 3,878 specimens which were screened for antibody to HIV in Kinshasa, Zaire, we observed that a testing hierarchy consisting of duplicate HIVCHEK screening assays followed by duplicate Serodia-HIV confirmatory assays resulted in correct confirmation of all ELISA- and Western blot-positive specimens. We conclude that such a testing hierarchy can produce highly accurate results for identification of positive specimens in routine HIV testing and provides a practical alternative to conventional methods of HIV screening and confirmation.

Field testing and comparative evaluation of rapid, visually read screening assays for antibody to human immunodeficiency virus.

Five rapid, visually read assays for detection of antibody against human immunodeficiency virus (HIV) were evaluated on fresh serum samples from 4000 prospective blood donors at Mama Yemo Hospital, Kinshasa, Zaïre. The sensitivity of the assays, based on 214 specimens positive by western blot, ranged from 84.6% to 99.1%. The specificity, based on 3664 samples negative by enzyme-linked immunosorbent assay (ELISA) or western blot, ranged from 92.7% to 98.8%. Three readers scored each test result independently; disagreement about test interpretation occurred in 1.2-8.3% of the specimens. There was no correlation between assay performance and assay principle (agglutination or dot immunobinding) or antigen source (viral lysate or recombinant). Assays such as these can be readily implemented in a developing country transfusion centre, where blood screening by ELISA is not practicable.

PIP: 5 rapid, visually read blood screening tests for HIV that require no refrigeration or electric power were evaluated on 4000 sera at Mama Yemo Hospital, Kinshasa, Zaire. The tests were 2 1st generation agglutination assays (Quick PHT-HIV, Salck Industries, Sao Paulo, Brazil; and Serodia-HIV, Fujirebio, Tokyo) a 2nd-generation agglutination assay (Recombigen-LA-HIV-1, Cambridge Bio-Science, Worcester, Mass), and 2 2nd generation dot immunobinding assays (HIVCHEK, DuPont, Wilmington, Del, and UCD DOT EIA, University of Ca, Davis, Ca). The blood samples were tested in batches, on east test, confirmed by ELISA, and 1 in 10 by Western blotting. 214 of the sera were positive by Western blot (5.5% prevalence). True positives ranged from 181-212, 211 by ELISA. False positives ranged from 44-267, 71 by ELISA. False positives ranged from 44-267, 71 by ELISA. Variability among test readers was least with the DuPont assay (1.2%), and gretest with the UCD (8.3%). Best agreement between initial and repeat tests was obtained for the DuPont and Fujirebio assays. All 5 tests could be done within 2 hours, the DuPont and Cambridge tests within 10 minutes. None of the tests required electrically powered equipment, although both the Fujirebio and Salck test needed precision pipettes. Technicians found the DuPont test the easiest to read, and the UCD the most difficult. The UCD test seemed to be the most difficult to learn. The DuPont and Fujirebio assays were the most sensitive and specific, and were considered the easiest to perform and interpret. While the DuPont test took only 5 minutes compared to 2 hours for the Fujirebio, the Fujirebio test was the cheapest.