Immunity to Salmonella typhimurium infection: characterization of antigens in active protection by polyacrylamide gel electrophoresis.

Immunity to challenge with Salmonella typhimurium (strain SR-11) was studied in NIH/NMRI Swiss mice. Viable organisms induced the best protection, but ribosomes were the best immunogen of the subcellular fractions. Antigens with lower concentrations of protein did not induce protection as well as antigens which had higher concentrations of protein. Acrylamide gel electrophoresis of the SR-11 subcellular components, fractionation, and differential staining of the gel columns indicated that the immunogen is a high-molecular-weight glycoprotein or mucopolysaccharide.