ABSTRACT
<p><b>OBJECTIVE</b>To establish a recombinant plasmid of CFP32 of Mycobacterium tuberculosis in E. coli, and to analyze its antigenicity.</p><p><b>METHODS</b>Rv0577 gene was amplified by polymerase chain reaction from genome of Mycobacterium tuberculosis, and then cloned into vector pMD18-T followed by the subclone into the expression vector pET21a. Recombinant CFP32 was expressed and purified. The antigenicity of the recombinant protein was analyzed by using Western-blot. The purified recombinant CFP32 protein was used as an antigen to screen the sera of 7 pulmonary TB patients (n = 97), as well as the other pulmonary disease patients (n = 25), and the clinically healthy controls (n = 38) by ELISA.</p><p><b>RESULTS</b>Recombinant plasmid of CFP32 was established, and be expressed efficiently in E. coli BL21 (DE3). The relative molecular mass of the protein was about 300,000 by SDS-PAGE analysis. The protein purified by Ni-NTA was in a purity over 90%, which was confirmed by Western-blot analysis. ELISA analysis showed its sensitivity and specificity were 63.9% (62/97) and 96.8% (2/63) respectively.</p><p><b>CONCLUSION</b>The recombinant expression plasmid pET21a CFP32 has been constructed and CFP32 proteins has been successfully expressed and be purified in E. coli and, ELISA analysis has identified the recombinant CFP32 as a candidate antigen for TB serodiagnosis.</p>