[Corynebacterium diphtheriae nontoxigenic strain carrying the gene of diphtheria toxin].

Among 828 C. diphtheriae nontoxigenic cultures isolated in different region of Russia in 1994-2002, 114 cultures (13.8%) had the gene of diphtheria toxin (gene tox) and were thus called nontoxigenic tox-carrying (NTTC) strains.

[Genetic structure of Corynebacterium diphtheriae strains isolated in Russia during epidemics of various intensity].

The genetic structure of C. dipthteriae toxigenic strains isolated in Russia during the period of more than 50 years was analysed. The use of the method of ribotyping made it possible to register 17 C.

[Temperature-dependent changes in immunochemical properties of lipopolysaccharides of yersinia pestis].

The preparations of pilopolysaccharides (LPS) of virulent and avirulent Y. pestis strains, which have a different composition, were cultivated at different temperatures. Despite the cultivation temperature of parental cells, all LPS preparation inhibited the passive hemagglutination reaction (PHR) of the red blood cells sensitized by LPS isolated from the cultures grown at 26 degrees C by using homologous antisera.

[Comparative characterization of the physico-chemical properties of lipopolysaccharides of Yersinia pestis and R-mutants of enterobacteria].

Electrokinetic potentials (EKP) of the cells of R mutants of Escherichia coli and Salmonella minnesota and cells of Yersinia pestis strains EV (line NIIEG), 358/12 P-, TWJ, Java, and 231 (708) were determined, as well as EKP of lipopolysaccharide (LPS) preparations isolated from these bacteria. The electric characteristics of the cell surfaces of the strains under investigation were demonstrated to correlate with the LPS charge and the reduction extent of their molecules. Acidic hydrolysis of LPS on the cell surface resulted in the leveling of the distinctions in EKP values (their reduction to the same level).

[In vitro development of fluoroquinolone resistance in the glanders pathogen].

To improve the scheme for the therapy of malleus, the possible development of fluoroquinolone resistance in the cells of Pseudomonas mallei was studied. The frequency of the mutations determining the resistance to oxolinic acid, norfloxacin, enoxacin, ofloxacin and ciprofloxacin was detected. The spectrum of the cross resistance in the strains was investigated.

[Cloning and detailed mapping of the fra-ymt region of the Yersinia pestis pFra plasmid].

The genetical libraries of the pFra plasmid of Yersinia pestis genes were obtained by insertion into the PstI, SalGI, EcoRI, XhoI restriction sites of the cosmid vector pHC79. The immunochemical analysis of the recombinant clones has revealed the clones synthesizing the antigen Fl (fraction I) and mouse toxin (Ymt--Yersinia pestis murine toxin). The restriction analysis of the plasmids from antigen synthesizing clones has permitted to construct the detailed physical map of the fra-ymt region of the pFra plasmid the size of 22 kb.

[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.

[Isolation and characteristics of the biological and genetic properties of neamin-resistant mutants of Salmonella typhimurium and Salmonella dublin candidates for vaccine creation].

Mutants, resistant to neamine and spectinomycin, have been isolated from S. typhimurium and S. dublin highly virulent strains.

[Auxotrophic mutations formed on the incorporation into the E. coli C600 chromosome of transposon Tnl that determines ampicillin resistance].

Incorporation of transposone Tnl of ampicillin resistance into the chromosome of E. coli C600 resulted in formation of at least 8 types of auxotrophic mutants. The transposone incorporates mainly into the loci the damage of which induces proline deficit (20 per cent).

[Isolation and characteristics of deletion mutants of thermosensitive plasmid pEG1].

Phenotypic revertants of temperature-sensitive in self-maintenance plasmid pEG1 derived from R-factor RP4 were studied. The study indicated a sertain part of them to be variants without ampicillin resistance. The frequency of pEG1 ampicillin sensitive (Aps) derivatives is about 5.

[Preparation and comparative evaluation of experimental anthrax diagnostic sera in experiments on animals].

The authors present the results of studies on obtaining and comparative assessment of experimental anthrax diagnostic sera in experiments on various animals. Donkeys, sheep, horses, rabbits and monkeys (Papio hamadryas) were immunized with the STI-I vaccine by a single scheme. The activity of the obtained sera was tested in the diffuse precipitation reaction by the amount of the detected antibodies and the titre.