Objective    To express and purify Mycobacterium tuberculosis 38kDa (phosphate transport system protein 1

PstS1)-U1(urine protein 1) fusion antigen and determine its immunological activity.     Methods    The PstS1-U1 fusion gene was amplified from genomic DNA of Mycobacterium tuberculosis by Gene SOEing methods and cloned into pET28a--a prokaryotic expression plasmid. The recombinant PstS1-U1 fusion protein was expressed and purified by affinity chromatography. The immunological activity of purified fusion protein was determined by Western blot with serum of active tuberculosis patie

nts.     Results    The pET28a-PstS1-U1 expression plasmid was constructed successfully and the expressed fusion protein was 57×10

3

in molecular weight. Western blot indicated that the purified protein was able to react with antibody in serum of active tuberculosis patients.     Conclusion    The PstS1-U1 fusion antigen was expressed and purified

which lays the foundation for its potential application in the serodiagnosis of tuberculosis.