Abstract:

Objective To construct a recombinant plasmid encoding Tp0821, a membrane lipoprotein of T. pallidum, express and purify this protein, and to evaluate its immunocompetence. Methods The recombinant plasmid pQE32/Tp0821 was constructed and induced to express the corresponding protein. Then, New Zealand rabbits were immunized with purified recombinant protein to prepare polyclonal antibodies, and the titer of polyclonal antibody was determinated. Indirect ELISA was developed with the recombinant protein of T. pallidum as coating antigen to detect 80 control sera and 150 FTA-ABS-positive sera. Results The recombinant plasmid pQE32/Tp0821 was constructed and a fusion protein with expected molecular weight was expressed. Specific humoral response was elicited by the recombinant protein in New Zealand rabbits and the antibody titer reached 1 ∶ 6 400. Compared with FTA-ABS test, the indirect ELISA showed a sensitivity and specificity of 92.6% and 98.6%, respectively, in the detection of control and clinical sera. Conclusion The recombinant protein Tp0821 shows excellent immunocompetence, which can be applied to the serological diagnosis of syphilis.

Key words: Treponema pallidum, Tp0821 recombinant protein, Immuno-competence.