Characterization of dermonecrotic toxin produced by serotype D strains of Pasteurella multocida

Dermonecrotic toxin (DNT) produced by serotype D strains of Pasteurella multocida, isolated from pigs, was characterized and compared with DNT produced by Bordetella bronchiseptica. The DNT prepared by sonication from P multocida or B bronchiseptica had dermonecrotic activity and lethal toxicity for guinea pigs and mice, and also induced marked atrophy of spleens in the mice. Toxicity of P multocida or B bronchiseptica DNT was completely inactivated by heating at 70 C for 30 minutes, and was reduced by treatment with trypsin, formalin, or glutaraldehyde, indicating that the DNT may be a protein. Although biologic and toxic properties of P multocida DNT were similar to those of B bronchiseptica DNT, cross-neutralization tests between P multocida and B bronchiseptica indicated that DNT from the 2 bacterial species were serologically distinct.