Alternative methods of attenuating Salmonella species for potential vaccine use

Because of their invasive properties, Salmonella species are uniquely suited for use as live oral vaccines, and mutants attenuated in general metabolic functions show promise as vaccine strains. We have identified a Salmonella choleraesuis transposon mutant which is deficient in abilities to attach to, invade or penetrate through animal cells. This mutant is avirulent in mice, yet is able to persist within the liver, spleen and gut-associated lymphoid tissue for periods which may be adequate for induction of secretory, humoral and cell-mediated immunity. This and other strains attenuated in factors specifically required for Salmonella pathogenesis may have potential as vaccine strains.