[Evaluation of the anti-TP antibody latex agglutination immunoassay in routine testing and a clinical viewpoint]

Abstract

We evaluated TP-LAIA (anti-TP latex agglutination immunoassay) and compared the results with those obtained using Serological Tests for Syphilis (STS), namely Venereal Disease Research Laboratory (VDRL) method and Rapid Plasma Reagin (RPR) test. We also examined early-stage antibody reaction using rabbits infected with active pathogen, and analyzed early-stage syphilis patient serum with IgM class anti-TP antibody. Based on routine test results and case history reviews for possible syphilis infection, TP-LAIA showed high specificity, 0.64% false positive results in comparison with 13.5% by VDRL method. Sensitivity was also significantly higher than TP-Hemagglutination Assay(TPHA). In the examination of TP early-stage infection, the fastest positive antibody reaction was observed with TP-LAIA, indicating its significance in the diagnosis of early-stage syphilis. TP-LAIA was confirmed to give a reliable reaction with IgM class anti-TP antibody. TP-LAIA results coincided with VDRL method results in the decrease in anti-treponemal antibody titers following medical treatment, suggesting that TP-LAIA will be a valuable tool for monitoring the effect of medical treatments. We concluded that not only the high sensitivity and specificity of TP-LAIA assay and its suitability for automation make it an ideal screening test, but also the assay performs sufficiently and satisfactorily for its use in monitoring medical treatments.