[Cloning and expression of Treponema pallidum antigen TpN17 and an epitope of TpN44.5 and clinical application].

ABSTRACT

OBJECTIVE: To investigate the cloning and expression of Treponema pallidum (TP) specific antigen TpN17 and an epitope of TpN44.5 and the clinical application of this fusion antigen. METHODS: TpN17 gene was amplified from the genome of TP and an epitope of TpN44.5 was spliced to the 5' end of TpN17 gene. This modified TpN17 gene was cloned into the expression vector pGEX4T-2. The recombinant fusion antigen was purified by affinity chromatography and then an enzyme-linked immunosorbent assay (ELISA) kit was prepared. With this kit, the sera of 10 normal persons and 10 TP patients were tested. RESULTS: The molecular weight of the purified fusion antigen was 45,000. Tested with ELISA, 10 serum samples of the TP patients were positive and another 10 of the normal persons were negative. ELISA equipped with the GST-epi-TpN17 antigen showed higher sensitivity and specificity as compared with routine methods. CONCLUSION: The recombinant fusion TP specific antigen GST-epi-TpN17 was suitable for the preparation of ELISA kit in clinical examinations.