Protective efficacy of maternally derived passive immunity against virulent challenge by Bordetella bronchiseptica followed by toxigenic pasteurella multocida in suckling piglets

摘要

The purpose of this study was to evaluate the maternal passive immunity protection of piglets against atrophic rhinitis induced by challenge with Bordetella bronchiseptica followed by challenge with toxigenic Pasteurella multocida. Nonimmune sows were vaccinated approximately 6 and 2 weeks prior to farrowing. A control group of nonimmune sows were not vaccinated. Piglets from both groups of sows were then challenged at 4 weeks of age with B. bronchiseptica followed 3 to 6 days later by challenge with toxigenic P multocida type D. Piglets were evaluated when 8 weeks old. B. bronchiseptica agglutinin titers in sows were measured at the time of each vaccination and 1 week after farrowing. A strong response to vaccination was observed (reciprocal of the geometric mean titers wk after farrowing, 13,404 for piglets from vaccinated sows vs. 6,146 for piglets from nonvaccinated sows). Piglet serum was evaluated for agglutinin titers before challenge. The reciprocal of the geometric mean titer of 4-week-old piglets from vaccinated sows was 7,247, whereas that of piglets from nonvaccinated sows was 1,777. Piglet serum was evaluated for agglutinin titers before challenge. A neutralizing antitoxin assay was used to measure P multocida type D toxoid in sera from sows 1 week after farrowing and in colostrum at farrowing. The reciprocal of the geometric mean titer in sera from vaccinated and control sows was 2.76 and 1.30, respectively. Titers in colostrum at farrowing were 39.11 and 1.25 for vaccinated and control sows, respectively. Piglet sera were evaluated for neutralizing antitoxin titers before challenge (3.05 vs. 1.25). There was no correlation between piglet serum titer and protection against atrophic rhinitis. Space between the dorsal and the ventral turbinates and the walls of the nasal cavity were measured on both sides of the cavity. The sum of the 4 measurements (in mm) resulted in the snout score. Mean snout scores in piglets at 8 weeks of age indicated significant (P (0.05) protection against atrophic rhinitis (pigs from vaccinated sows, 9.84 mm; pigs from nonvaccinated sows, 29.83 mm).