Multisite evaluation of four anti-HIV-1/HIV-2 enzyme immunoassays. Australian HIV Test Evaluation Group.

The performance of four enzyme immunoassays, manufactured by Abbott, Diagnostics Pasteur, Genetic Systems, and Organon Teknika, for the combined detection of anti-human immunodeficiency virus type 1 (HIV-1) and anti-HIV-2, was examined in a multisite evaluation. The collaborative efforts of 7 Australian Red Cross Blood Transfusion and 12 Australian Public Health Laboratories minimized potential biases in data by providing large numbers of anti-HIV-1-negative and -positive samples. Sensitivity was estimated using samples that were positive for anti-HIV-1 from individuals known to be infected and seroconversion samples. Sensitivity estimates in the four assays were 99.71, 99.94, 99.49, and 99.68%, respectively. Specificity was measured using fresh, sequential blood donations and samples with previous false-positive reactions in other assays. Specificity estimates from blood donations were 99.92, 99.46, 99.67, and 99.85%, respectively. The data were analyzed further using the delta statistic, which distinguishes the performance of assays of similar sensitivity and specificity by providing a measure of how well results in a population of positive or negative samples are removed from the assay's cutoff value.

A comparison of the performance of nine commercially available anti-HTLV-I screening assays.

The performance of eight anti-HTLV-I enzyme immunoassays (EIAs) and one particle agglutination assay was compared with respect to sensitivity, specificity and delta values, by testing a panel containing 99 anti-HTLV-I positive and 126 anti-HTLV-I negative samples which had been characterised by western blot and some by radioimmunoprecipitation assay. The estimated sensitivities produced by these assays ranged between 99% and 100% and estimated specificities were between 95.2% and 100%. The performance of the EIAs was further differentiated by using the delta value which measures the ability of an assay to separate the positive and negative populations from the cutoff value. A delta value could not be calculated for the particle agglutination assay (Serodia) because the test readings were not quantitative. The EIAs most likely to correctly identify anti-HTLV-I positive and anti-HTLV-I negative samples included the Cambridge Biotech, Dupont, Genetic Systems and Olympus assays. Our findings suggest that there may be some difficulty in correctly identifying anti-HTLV-I negative samples using the Abbott, Cellular Products Incorporated (CPI), Coulter and Diagnostic Biotechnology assays. The Serodia assay produced comparable sensitivity and specificity to the eight EIAs.

An evaluation of competitive and second generation ELISA screening tests for antibody to HIV.

Two competitive anti-HIV ELISA screening assays (Behring and Wellcozyme) and two second generation assays using antigens generated by recombinant DNA technology (Abbott) and synthetic peptides (Biochrom) were evaluated against common panels of anti-HIV positive sera and sera known or thought likely to give false positive reactions. The assays were also tested on fresh sequential blood donations. Conventional estimates of sensitivity and specificity did not reveal a significant difference between the assays. Statistical analyses using log10 transformed data to determine delta values (the distance of the mean optical density (OD) ratio from the cut-off measured in standard deviation units) showed the Abbott assays to have the highest probability (greater than 99.99%) of detecting anti-HIV positive samples and the Behring assay as having the highest probability (greater than 99.99%) of correctly identifying anti-HIV negative specimens. The combined data from conventional estimates of sensitivity and specificity and delta values suggests that the Abbott assay is the test of choice for screening purposes.

Evaluation of a new assay for antibodies to LAV/HTLV III.

The sensitivity, specificity and reproducibility of an enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to LAV/HTLV III produced by Genetic Systems was assessed with the identical panel of sera used in previous evaluations of anti-HTLV III ELISAs. The results from this study show that the Genetic Systems anti-LAV/HTLV III ELISA proved to be of equivalent sensitivity and to have higher specificity than assays currently used in Australia for screening purposes while maintaining high levels of intra- and inter-laboratory reproducibility.