EVALUATION OF A NEW COMPETITIVE IMMUNOASSAY (BIOELISA SYPHILIS) FOR SCREENING FOR TREPONEMA-PALLIDUM ANTIBODIES AT VARIOUS STAGES OF SYPHILIS

The BioElisa Syphilis, a new competitive enzyme immunoassay (EIA) for Treponema pallidum whole antigen that uses specific human immunoglobul in G (IgG) antibodies as the competitor, was evaluated for potential u se in screening for syphilis at various stages, The results obtained b y this competitive EIA were compared with those obtained by the fluore scent treponemal antibody absorption (FTA-abs) test and the T. pallidu m hemagglutination assay (TPHA), Serum samples from 434 patients with positive TPHA and FTA-abs test results, including patients with primar y, latent, secondary, and tertiary syphilis and neurosyphilis, were in vestigated, Two samples tested negative by competitive ELA but were we akly reactive by the TPHA and the FTA-abs test, Sixteen serum samples from patients with clinically documented active syphilis, including se veral patients infected with human immunodeficiency virus, tested posi tive by the competitive EIA, There was a direct inverse correlation be tween EIA indices and titers in the TPHA and the FTA-abs test for all samples that tested positive, Specificity was assessed by testing 358 serum samples which tested negative for syphilis by TPHA and the FTA-a bs test, including 100 serum samples from patients with documented inf ectious or autoimmune diseases, Only two serum samples gave a weakly p ositive EIA result, Thus, competitive EIA. had a sensitivity of 99.5% and a specificity of 99.4% relative to the results of the FTA-abs test and TPHA, Our evaluation shows that BioElisa Syphilis is a sensitive, specific, and simple assay for screening for syphilis.