Abstract: Objective To prepare specific recombinant Treponema pallidum antigen with genetic engineering technique. Methods The specific antigen genes were cloned by polymerase chain reaction (PCR) technique, and checked by sequencing. The procedures of translation, induction and expression were performed using pMAL^TM-c2. Results The genes encoding TP 15 000, TP 17 000 and TP 47 000 were obtained by PCR. The antigens of TP 17 000 and TP 47 000 were successfully expressed in E.coli TB₁. The recombinant TP 17 000 and TP 47 000 produced showed a highly specific serological activity. Conclusion The specific TP antigen gene is successfully expressed in E.coli with products showing high specificity to the sera of patients with syphilis, which might be used for the diagnosis of syphilis.

Key words: Treponema pallidum, Gene cloning, DNA,recombinant