Immunizing Effect of Live Vaccine Prepared from Various Mutants of Salmonella Having Different Cell Wall Polysaccharides

抄録

Immunizing potencies of vaccines prepared from various strains of Salmonella were graded by comparing the mortality rate of immunized mice after challenge with highly virulent strains of either Salmonella enteritidis or S. typhimurium. The resistance against this challenge infection was shown to be conferred by joint immunization with a specific factor, which was represented by O specific lipopolysaccharide of smooth strains, and cross-protection factor, which was a major potent factor in live vaccine. The distribution of this cross-protection factor in rough mutants of S. typhimurium was found to be limited to strains which possessed a polysaccharide chain longer than that of glucose1-less mutant. The potency conferring cross-resistance was found to be maintained partly in formalin-killed cells and cell walls of the strains harboring cross-protection factor but not in lipopolysaccharide extracted from such strains.