RESEARCH ARTICLE Summary

Different strategies have been developed to produce vaccines against Pasteurella multocida. The approach described herein involves overexpression on the bacterial cell surface of Fur-regulated IROMPs (iron-regulated outer-mem-brane proteins). Accordingly, the ability of fur mutants to promote heterologous protection was examined in a Swiss mouse animal model. Two fur mutants derived from P. multocida were isolated, one of which was also defective in the OmpH pro-tein. In mice challenged with virulent P. multocida, outer-membrane protein (OMP) extracts of fur cells conferred the same protection as obtained with wild-type cells grown in iron-depleted medium. Total protection was achieved with 40 μg of OMP extract from the fur ompH mutant. Mice administered heat-inactivated fur ompH cells were 60 % cross-protected. The pres-ence of a galE mutation in these cells did not further increase the protection level. Additionally, cell disruption by sonication provoked a higher level of protection than conferred by heat-treated cells. Taken together, the results showed that P. multoci-da fur ompH cells offer a simple and suitable approach for cross-protecting animals against infection with P. multocida. [In