Immunity in experimental salmonellosis. 3. Comparative immunization with viable and heat-inactivated cells of Salmonella typhimurium.

Vaccination with viable cells of an avirulent Salmonella typhimurium galE mutant provides mice with solid specific immunity against subsequent infection with a virulent smooth strain. Such a live vaccine is markedly more potent than one prepared from inactivated cells of the virulent smooth strain. The superiority of the live vaccine is particularly well demonstrated when the oral route of application is used. The protective capacity of the galE mutant is based on its ability to synthesize complete smooth-like cell wall lipopolysaccharide in vivo.