Abstract: ObjectiveTo clone, express and purify the recombinant fusion protein 38kD-16kD of Mycobacterium tuberculosis, and to evaluate its potential value in TB serodiagnosis. MethodsThe genes coding 16kD and 38kD proteins were amplified by polymerase chain reaction (PCR) from the genome of Mycobacterium tuberculosis H₃₇Rv,and then cloned into expression vector pET21a,respectively. The fusion proteins 38kD-16kD were expressed in E.coli BL21(DE3). It was purified by his-tag of the fusion protein and renaturated by semipermeable membrane. Recombinant protein was analyzed by Western-blot. The purified recombinant protein was used as antigens to screen the sera from the patients with pulmonary TB (n=96),as well as other pulmonary disease (n=50), and clinically healthy controls(n=38) by ELISA. ResultsThe recombinant plasmid pET21a-38kD-16kD was obtained. The relative molecular mass of the protein was about 65000 Da by SDS-PAGE analysis. Specific immunogenicity of the recombinant protein was confirmed by western blot analysis. The Results of ELISA showed that the sensitivity and specificity of 38kD-16kD antigen were 80.2%(77/96) and 90.9%(80/88),respectively. ConclusionThe recombinant fusion protein 38kD-16kD was successfully expressed and purified, and may be a potential candidate of serodiagnostic reagent.

Key words: Mycobacterium tuberculosis, recombinant fusion proteins, serologic tests