| Abstract: | Eight calves were immunized with live auxotrophic Salmonella typhimurium mutants (aro -SL 1479, gal E 3821) and twelve calves with phenol-killed whole-cell S. typhimurium vaccine, respectively. The clinical status of the animals was followed and serial reisolation of vaccine and challenge strains from faeces was attempted. The immunization of calves with the live aro- auxotrophic S. typhimurium SL 1479 mutant proved to be unsuitable due to the death of calves after revaccination. The calves immunized with live auxotrophic gal E S. typhimurium CCM 3821 mutant proved to be protected against challenge with virulent S. typhimurium 4/5 strain administered orally at a dose of 10(6) colony forming units (CFU). The postvaccination complications showed serious shortcomings. The immunization of calves with three doses of whole-cell inactivated vaccine containing 5 strains of S. typhimurium was effective against oral challenge with virulent S. typhimurium 4/5 at a dose of 10(6) CFU. |
