A crude cytotoxin vaccine protects sheep against experimental Pasteurella haemolytica serotype A2 infection |
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Authors: | A D Sutherland W Donachie G E Jones M Quirie |
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Affiliation: | Moredun Research Institute, Edinburgh, Gt. Britain. |
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Abstract: | Three vaccines containing Pasteurella haemolytica serotype A2 antigens were tested for their ability to protect sheep against a homologous challenge. A crude cytotoxin preparation in combination with a sodium salicylate extract (SSE) or crude cytotoxin alone were highly protective (98 and 86%, respectively), whereas SSE alone was poorly (47%) protective. These findings indicated that the crude cytotoxin was an essential component of a protective vaccine. Protection correlated with serum cytotoxin-neutralising (CN) titres and bactericidal activity, which were stimulated by antigens in the crude cytotoxin preparation. |
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