[Construction and characterization of ompH gene knockout mutant of avian Pasteurella multocida C48-3].

Objective: To study the role of the outer membrane protein H (OmpH) in pathogenicity of avian Pasteurella multocida.

Methods: The ompH knock-out mutant of avian P. multocida C48-3 was constructed by homologous recombination. The DNA replacement was confirmed by PCR, RT-PCR and Western blot. We compared the differences of biological characteristics such as growth rate, capsular structure, adhesion ability and virulence between the ompH knockout mutant of C48-3 Delta ompH and parent strain C48-3, as well as the complemented strain C48-3C.

Results: C48-3 Delta ompH was successfully constructed. Electron microscopy examination of C48-3 Delta ompH shows the absence of capsular material compared to the parent strain C48-3 and complemented strain C48-3C. The adhesion assay shows that the number of C48-3 Delta ompH adhered to CEF cells was significantly lower than that of C48-3 and C48-3C. C48-3 Delta ompH was relatively attenuated in mice by intraperitoneal injection.

Conclusion: The construction of C48-3 Delta ompH would facilitate further study on pathogenesis of avian Pasteurella multocida.