[High-immunogenic mutants of Salmonella with two independently of each other attenuating markers as potential vaccines from bacteria capable of multiplication. I. communication: usefulness of the purin-auxotrophy for the isolation of high-immunogenic and stable double-marker strains (author's transl)].

The Salmonella example demonstrates a principle for the isolation of high-immunogenic, stable Salmonella-mutants with two independently of each other attenuating mutations as potential vaccines from bacteria capable of multiplication. The isolation of such double-marker vaccination-strains is verified by the treatment of a single-marker strain (for instance an attenuated high-immunogenic auxotrophic pheno-type) with mutagen and the following selection of clones with the marker purin-auxotrophy as a second attenuating mutation. The demonstrated double-marker strains S. typhimurium his-155 pur-4 and S. dublin met-91 pur-23 are designated by the following parameters: Stability under the conditions of the practical vaccine application; immunogenicity for mice by one immunization only, and separability from homologous wild strains with simple laboratory methods.