Cloning and expression of the gene coding for Mycobacterium tuberculosis antigen Ag85B.

Objective To clone and express the gene coding for Mycobacterium tuberculosis antigen Ag85B, and obtain the purified recombinant protein Ag85B.MethodsThe Ag85B gene was amplified from the genomic DNA by polymerase chain reaction (PCR) in vitro, and cloned into vector PET23a (+) to construct the recombinant plasmid. The recombinant plasmid was transformed into expressive vector Escherichia coli BL21 (DE3), and induced with IPTG; the presence of recombinant protein in the expression vector was analyzed by SDS-PAGE and Western blot.The recombinant Ag85B protein was purified with His Bind Purification Kit.ResultsThe recombinant plasmid Ag85B was correctly constructed, and the recombinant Ag85B protein was expressed as inclusion body in E.coli BL21 (DE3).ConclusionThe target gene has been cloned into host bacterium. The purified recombinant protein Ag85B paved the way for further study.