[Laboratory-based evaluation of a newly developed immunochromatographic test method by using synthesized oligonucleotide-bound protein probes for simultaneous detection of hepatitis B surface antigen (HBsAg) and specific antibodies to Treponema pallidum].

An immunochromatographic test method using synthesized oligonucleotide-bound protein probes was newly developed and evaluated for simultaneous detection of hepatitis B surface antigen (HBsAg) and specific antibodies to Treponema pallidum (TP). The test principle includes, first, antigen-antibody reaction, and secondly, DNA (oligonucleotide)-DNA interaction. The test device is composed of colloidal gold-labeled HBs antibody and TP antigen, and oligonucleotide-labeled HBs antibody and TP antigen. When the test sample contains HBsAg and/or TP specific antibody, the colloidal gold-labeled probes and oligonucleotide-labeled probes will make a sandwich complex with the target. Then, the formed complex migrates and is immobilized by the respective complementary oligonucleotide fixed on the different lines of the membrane. The color development of colloidal gold was visually read after 20 min and/or 60 min incubation, and easily interpretable, positive or negative. When the performance panels of Boston Biomedica Inc. (BBI) for HBsAg and TP-specific antibody, the results indicated; first, the most positive serum and plasma specimens with 1.2 IU/ml of HBsAg were correctly determined as positive, and secondly, all the test results for TP-specific antibody were comparable to the results of fluorescent treponemal antibody test (FTA-ABS). However, when the seroconversion panel of BBI for hepatitis B virus (HBV) infection, the seroconversion was delayed 20 to 30 days when compared to HBV DNA detection. Also, when the clinical serum and plasma samples were tested, sensitivity and specificity were estimated to be 87.0% and 100% for HBsAg, and both 100% for TP-specific antibody, respectively. With these results, we can conclude that this newly developed immunochromato-graphic test method will be applicable to simultaneous detection of multiple antigen and/or specific antibody in a single device, and will be expected to be widely applied in a clinical setting.