Compared efficiency of a killed vaccine of Salmonella typhimurium, a live vaccine and an antigenic fraction in oral immunization of mice.

In an attempt to determine the best method of immunizing mice by oral route against Salmonella typhimurium, the animals were vaccinated by means of a killed-pathogenic strain, an avirulent mutant of the same bacteria, and a protective antigen removed from the supernatant culture of this mutant. After changing doses of vaccines and the interval between vaccination and challenge, the results obtained show the superiority of the live vaccine and protective antigen with regard to the killed one. Under our experimental conditions enteral vaccination appears to be more effective than the parenteral one.