Abstract
The role of several outer membrane components as virulence factors is well established. We have now isolated spontaneous mutants and conjugational hybrids of smooth mouse virulent Salmonella typhimurium deficient in two major outer-membrane proteins. The lack of the 34,000- and/or 36,000-dalton proteins was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Mutants and recombinants were then tested for their mouse virulence by intraperitoneal inoculation and were found to be as virulent as the parent strain.