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  • Author or Editor: Clarence E. Chrisp x
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SUMMARY

Heat-labile toxin from a cell sonicate of a virulent typeD strain of Pasteurella multocida was purified by ammonium sulfate precipitation followed by ion exchange chromatography, gel filtration chromatography, and Polyacrylamide gel electrophoresis. Toxic activity was assayed during toxin purification by cytopathic effect in Vero or bovine embryonic lung cell cultures. Toxicity for cells correlated with dermonecrosis in guinea pig skin. Toxicity was accounted for by a single protein with a molecular weight of 149,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Rabbits were inoculated intranasally with purified toxin to determine whether toxin had a role in the induction of pneumonia in rabbits infected with P multocida. Pneumonia, pleuritis, acute hepatic necrosis, and splenic lymphoid atrophy were found in 4 of 5 rabbits. One of 5 rabbits had bilateral turbinate atrophy. Western blotting with monoclonal antibodies to toxin from a P multocida isolate causing atrophic rhinitis in pigs revealed the toxin that induces pleuritis and pneumonia in rabbits to be the same or a closely related toxin.

Free access
in American Journal of Veterinary Research

Summary

Naturally acquired turbinate atrophy in rabbits was associated with Pasteurella multocida infection. Several in vitro and in vivo studies were conducted to document toxin production from P multocida isolates and to determine the relation of toxin to atrophic rhinitis in rabbits. Ten isolates of P multocida serotype A:12 were obtained from adult New Zealand White rabbits with noninduced atrophic rhinitis. Specific-pathogen-free rabbits inoculated intranasally with isolates of P multocida developed rhinitis and turbinate atrophy. However, inoculation with filtrates of the same bacteria failed to induce turbinate atrophy. Cytotoxicity was observed in assays, using bovine embryonic turbinate cell cultures with extracts of P multocida, but not in agar overlay cytotoxicity assays, using bovine embryonic turbinate, bovine embryonic lung, or Vero cell cultures, or in a sandwich elisa, using monoclonal antibodies to purified P multocida toxin. Thus, turbinate atrophy was experimentally reproduced in rabbits with isolates of P multocida, but toxin was only detected in vitro by cell culture assay of P multocida extracts.

Free access
in American Journal of Veterinary Research