Salmonella derby cross-protection study.

An avirulent live (AVL), Salmonella choleraesuis vaccine (Salmo Shield Live [Grand Laboratories, Inc.]) was administered to pigs at weaning or 3 weeks of age. Two weeks after vaccination the vaccinated pigs as well as unvaccinated control pigs were challenged intranasally with a commonly isolated environmental Salmonella serotype, S. derby. At 2, 4, and 6 weeks after challenge, pigs were euthanized and cultured for S. derby. Although the number of pigs in this study was too small to draw any definite generalizable conclusions, the vaccinated pigs had significantly reduced reisolation rates of S. derby when compared with the control pigs. Further research in this area is needed.