Cloning and Expression of Virulent Protein CFP-10 from Mycobacterium bovis Strain AN5

Bovine tuberculosis caused by Mycobacterium bovis is an important disease that has negative effects on public health and entails economic loss. Traditional controlling programs for cattle  focus on test and slaughter strategy, and false positive is one of the disadvantages associated with tuberculin skin test. To overcome this limitation, proteins with high specificity have to be utilized.

The objective of this study was to clone and express virulent protein CFP-10 from Mycobacterium bovis AN5.

Full-length genes of cfp-10 were amplified by PCR technique. In parallel, pET23a(+) and PCR products were double digested by EcoRI and HindIII. Ligation was performed at 16˚C followed by transformation into competence E. coli DH5α. After being identified with sequencing, the cloned vector was transformed into E. coli BL21. Induction was performed by isopropyl-β-D-thiogalactopyranoside (IPTG). Urea 8M was used to dissolve the expressed protein in the inclusion body form. Recombinant protein was purified by Nickle-Resin, and urea was eliminated by decreasing the gradient.

The CFP-10 gene clone was proved by sequencing method. The CFP-10, as a 10 KDa protein, was confirmed by Western blotting using monoclonal antibodies. Based on the results, the recombinant protein was successfully cloned and expressed.

The results showed that cfp-10 gene was successfully cloned and expressed in prokaryotic system, indicating that this recombinant protein could be utilized in diagnostic kits against bovine tuberculosis in the future.