Role of Outer Membrane Protein H in the Pathogenesis of Avian Pasteurella multicida Strain C48-3

Abstract

The previous study has indicated that the targeted inactivation of ompH gene decreased the lethality of serotype A Pasteurella multocida C48-3 in mice after intraperitoneal injection. The ompH gene was cloned from P. multocida C48-3 and expressed in Escherichia coli M15,and immune serum was generated by immunizing rabbit with the purified recombinant protein OmpH. Differences of adhesion ability,serum resistance and antiphagocytic activity between the wild-type strain C48-3,mutant strain ΔompH and its complemented strain C48-3C were compared by biological experiments. The adhesion of wild-type strain and complemented strain to CEF cells was inhibited significantly by treatment with immune sera as compared to the treatment with normal serum. The mutant strain was sensitive to the bactericidal action of chicken serum,whereas the wild-type strain and complemented strain were both resistant. The mutant strain was readily taken up by mouse peritoneal macrophages in the normal rabbit serum,whereas the wild-type strain and complemented strain were both resistant. In addition,the rabbit antiserum against OmpH promoted the phagocytosis of C48-3 and C48-3C by mouse peritoneal macrophages,but mutant strain was not affected. These results demonstrate that the OmpH is a major virulence factor of P. multocida.