Molecular cloning and characterisation of the genes coding for passenger domain of the PmpD from Chlamydophila abortus CP16

The passenger domain gene of PmpD of swine Chlamydophila abortus CP16 was amplified, subcloned into the pet-32a(+) vector, then sequenced, and expressed in Escherichia coli BL21(DE3). The target protein was identified by Western blotting. It was demonstrated by sequence analysis that the passenger domain gene of Pomp18 contained 1317 bp that encoded a protein of 439 amino acids. The homology of the target gene was found to be 97.0%, 97.0%, 97.2%, 52.6%, 44.6%, and 87.5%, respectively, identical to that of the CPD13, S26/3, IB, TW-183, TW-396, and CAL-10 strains of C. aborts. The recombinant 65.3 kDa protein was identified by both SDS-PAGE and Western blotting. A positive reaction was observed with swine positive serum, while neither sheep serum nor avian serum reacted with the target protein. In conclusion, the passenger domain of PmpD gene was at first cloned and expressed successfully. The recombinant protein showed the species reaction and might play a major role in C. abortus infection.