Molecular aspects of the virulence of Pasteurella multocida

Molecules important to the virulence of all Pasteurella multocida are little known, but much has been learned of isolates causing atrophic rhinitis of pigs. A protein toxin purified from P. multocida or from a recombinant Escherichia coli reproduces atrophic rhinitis and leads to a reduction in weight gain; antitoxin is completely protective. Toxin is important for P. multocida colonization, especially in the presence of the Bordetella bronchiseptica cytotoxin. The P. multocida toxin binds rapidly to embryonic bovine lung cells in vitro leading to an alteration of cell shape without the metabolic and structural changes associated with other toxins. This indicates a novel biochemical mechanism. However, other work suggests a subunit mode of action structurally like hormones and other bacterial toxins.