[Serological test methods as replacement for infection trials in piglets to test the potency of E. coli vaccines for...

Escherichia coli (E. coli) related diarrhoea poses a major problem in piglet production. Vaccination of dams increases the antibody titre in their milk against relevant adhesion antigens. Transfer of maternal antibodies via the milk can serve to protect the suckling piglets from the disease. However, a marketing authorization for veterinary use of these vaccines requires potency determination as assayed in infection trials in piglets. Enzyme immunoassays testing the antibodies in blood serum and colostrum samples from vaccinated dams against the relevant adhesion antigens, F4ab, F4ac, F6 and F41, were developed to replace the very distressing infection experiments by in vitro methods. Eight vaccines authorized in Germany were included in the trials. Vaccinated sows showed significantly higher antibody titres in blood and colostrum than unvaccinated control animals. Thus the enzyme immunoassays appear to be suitable to detect antibodies against four important adhesion antigens, and can be used to replace the distressing infection trials in piglets.