Cloning,expression and purification of the gene of antigen culture filtrate protein 21 of Mycobacterium tuberculosis

In order to construct culture filtrate protein 21(CFP21) vector of Mycobacterium tuberculosis(Mtb) and express it in E.coli BL21,the cfp21 gene was amplified from Mtb H37Rv genomic DNA using PCR in vitro,and inserted into vector PET-28a(+) to construct the recombinant plasmid.The recombinant plasmid was then under the procedure of transforming into E.coli DH5α,plasmid extracting,PCR amplificating,sequencing,and transforming into E.coli BL21.The recombinant plasmid was induced with IPTG and identified using SDS-PAGE.Then the protein was purified using His Bind purification kit.Results demonstrated that CFP21 has been constructed,expressed and purified successfully.The molecular weight was about 24KD and the form of expression was inclusion bodies.In conclusion,the target gene has been cloned into host bacterium and expressed successfully.The purified recombinant protein CFP21 paves the way for TB diagnosis and vaccine development in the future.