| Abstract: | Protective properties of Ra- and Re-chemotypes of S. minnesota were studied in experiments on active and passive protection of albino mice from infection with a virulent S. typhimurium culture. Vaccines prepared from the Ra- and Re-mutants of S. minnesota were administered to the animals in the sum total dose of from 0.05 to 0.6 mg. Hyperimmune and normal rabbit sera were administered in doses of 0.3 and 0.5 ml. S. mineesota Ra- and Re-mutants in the doses tested proved to possess a weak protective activity: the level of the immunized mice nonspecific protection from the experimental salmonellosis failed to exceed the natural resistance level. Immunogenicity of Ra-mutant was markedly greater than the immunogenicity of Re-mutant. A marked protective activity against the experimental salmonellosis in mice was possessed by the antigenic complexes from the homologous strain only. |
