Immunity to Infection with Salmonella Typhimurium: Mouse-strain Differences in Vaccine- and Serum-mediated Protection

Three mouse strains in the C3H lineage--C3H/HeJ, C3HeB/FeJ, and C3H/HeNCr1BR--were tested for their ability to be protected against infection with Salmonella typhimurium by a panel of nonviable vaccines and by passive transfer of hyperimmune serum. These strains differ in their innate susceptibilities to infection with S. typhimurium, but all are histocompatible. The same vaccines showed a widely different ability to protect different mouse strains. Ability to protect was not closely related to the capacity of the mice to make either agglutinating or anti-O antibody (as shown by ELISA) in response to a particular vaccine. Passive transfer of antibody was shown to protect inherently resistant mice but not inherently susceptible strains. These observations suggest that reported discrepancies in vaccine efficacy among laboratories may be attributable to differences in the mouse strains used and raise the question as to what might be an appropriate mouse model for human infections with Salmonella species.