[Protective oral immunization against coli enterotoxemia in swine (author's tranls)].
The issue of immunity in the case of enteric infections caused by bacteria is still widely unresolved. To clarify this, weaned piglets 6-7 weeks of age were used as a model, because of the particular susceptibility to colienterotoxemia shown by them at this particular age. The experimental design was as follows. The animals were immunized orally and parenterally (i.v. and i.p. routes) by means of a vaccine consisting of bacteria incapable of reproduction. 14 days later, the animals were challenged orally with virulent EC-O 141 B 85 and EC-O 139 B 82. The results have shown that a) parenteral immunization did not induce protection against oral infection with virulent E. coli; b) repeated oral immunization produced measurable immunity against oral infection; and c) 1 7-hour broth culture proved to be particularly suitable for oral infection. Results also point to the fact local immunity in the intestine as present after enteric infection by bacteria may be artificially induced only by protective oral immunization.