Immunization of animals with gal E mutants of "Salmonella typhimurium".

A galactose epimeraseless (gal E) mutant of Salmonella typhimurium was investigated in mice, calves and poultry for its suitability as a live vaccine. In mice a very highly significant difference in the mortality rates was observed when vaccinated and non-vaccinated animals were challenged with virulent strains of S. typhimurium and S. dublin. In calves, doses of 10(6) and above of gal E mutant injected subcutaneously provided highly significant protection in terms of mortality and prevalence of symptoms when challenged orally with S. typhimurium. Renal lesions were found in a number of calves and studies were undertaken to investigate their pathogenesis. The results of these studies suggested that gal E. mutants were unlikely to produce the renal lesions. When day-old chicks were vaccinated orally with live gal E mutant of S. typhimurium and challenged orally 14 days later there was a statistically significant reduction in faecal shedding, in the salmonella carrier status at slaughter and in the numbers of salmonellae in the broiler house environment. The vaccine however, had a significant effect on the live weight gain of the birds.