[Genetic characteristics and protective properties of neamin-resistant mutant Salmonella typhimurium and S. dublin of the Nea(r) Str(s) and Nea(r) Str(r) 500 classes].

The genetic analysis of attenuated mutants, class Nea(r) Str(s), with the use of bacteriophage P 22 has shown that mutation rendering the mutants resistant to neamine is localized in gene nea A. In experiments with the intraperitoneal infection of mice, the appearance of this mutation in S. typhimurium and S. dublin virulent strains has been found to lead to the decrease of virulence in 100% of clones. On the basis of the data obtained in this investigation, region str-spc in S. typhimurium and S. dublin has been mapped. In contrast to mutation spc A, mutations nea A and str A have been shown to inhibit the action of amber suppressor. The investigation has confirmed the regularity, previously established for Shigella flexneri, concerning the relationship between the influence of mutations, occurring in the genes which determine resistance to neamine and streptomycin and control the synthesis of ribosomal proteins S4, S5, S12 and S17, on the virulence of S. typhimurium and S. dublin and the effect of these mutations on the accuracy of the translation of genetic information in the biosynthesis of protein: mutation spc A has been found to produce no changes in the virulence of salmonellae, while mutations nea A and str A cause its loss. Salmonella strains carrying mutations nea A and nea B have shown pronounced protective properties in experiments on mice.