Efficacy of Erysipelothrix rhusiopathiae bacterin administered in two different adjuvants against virulent challenge of pigs 20 weeks after vaccination

摘要

The purpose of this study was to evaluate protection against virulent Erysipelothrix rhusiopathiae challenge in pigs that had been vaccinated 20 weeks earlier with a vaccine containing 1 of 2 adjuvants. Pigs were randomly allotted to 1 of 3 groups: group A (Amphigen~(TM) adjuvant, n=20); group B (adjuvant B, n=10); group C (nonvaccinated controls, n=10). Pigs in groups A and B were vaccinated when approximately 3 and 6 weeks old. Blood samples were obtained for serologic analysis. Twenty weeks after the date of the second vaccination, all pigs were challenged with a virulent culture of E. rhusiopathiae, and then monitored daily for clinical signs of disease. Pigs were considered positive for disease: (1) if they were febrile (rectal temperature > 40.3C or > 40.9C for vaccinated and nonvaccinated pigs, respectively) for 2 consecutive days; (2) if they were febrile for 1 day and had other signs of disease (eg, recumbency, lethargy, metastatic skin lesions); or (3) if they had clinical signs of disease and E. rhusiopathiae was isolated. Vaccination with the Amphigen adjuvanted bacterin induced a substantial serologic response that peaked 2 weeks after the second vaccination. Nine of 10 (90%) control pigs were determined to be positive for infection following challenge. Fifteen of 20 (75%) pigs in group A were protected against challenge, whereas only 1 of 10 (10%) pigs in group B were protected. Results indicated that vaccination of pigs with E. rhusiopathiae bacterin vaccine with Amphigen provided significant (P (0.05) protection from challenge 20 weeks after vaccination.