Abstract: Objective  To construct the recombinant plasmid of  Mycobacterium tuberculosis Rv0222 in E.coli, and to study its potential value for serodiagnosis of pulmonary tuberculosis (TB). Methods  The gene coding Rv0222 protein was amplified by polymerase chain reaction (PCR) from genome of  Mycobacterium tuberculosis H37Rv，and then cloned into vector pMD18-T and subcloned into expression vector pET30a. Recombinant Rv0222 was expressed and purified. The antigenicity of the recombinant protein was analyzed by using Western blot. The purified recombinant Rv0222 protein was evaluated with the sera from pulmonary TB patients (n=82), the other pulmonary disease patients (n=28), and the healthy controls (n=32) by ELISA. The data were analyzed using professional medical software MedCalc 11.5.0. Results  Recombinant plasmid of Rv0222 was established, and the relative molecular mass was about 27 000 by SDS-PAGE analysis. The protein purified by Ni-NTA was in a purity over 95%, which was confirmed by western blot. The results from ELISA showed that its sensitivity and specificity were 69.5% (57/82) and 90.0% (54/60)，respectively. There was significant difference between TB patients and the controls (t=25.78，P＜0.0001). Conclusion  The recombinant protein Rv0222 was successfully obtained and might be used as a potential candidate antigen for TB serodiagnosis.

Key words: Mycobacterium tuberculosis, Recombinant proteins, Bacterial proteins, Enzyme-linked immunosorben assay