Biomedical subjects
Publications and source records attributed to P I Anisimov.
Y. pestis high repeated sequences DNA (HRS) used as probes in the blot hybridization procedure made it possible to reveal some tendencies of their location on the chromosome, namely, the correlation with the regions where Y. pestis strains were isolated, correlation with the stability of their properties and, perhaps, with the variation of individual strains.
This paper was prepared on the basis of a report presented at the first Congress of the All-Russian Society of Geneticists and Breeders (December 1994, Saratov, Russia). Analysis of published data and the authors' own investigations enabled them to propose a concept of evolution of pathogenicity within the Yersinia genus. They concluded that phenotypic features conferred by yersinia plasmids should be considered taxonomic traits.
The results of molecular-genetic studies performed by Russian specialists in plague research are discussed. On their basis, new concepts concerning the factors determining virulence of the plague bacterium were formulated, and certain aspects of Yersinia taxonomy were clarified.
A conceptual model of the Yersinia pestis Ca(2+)-dependence mechanism is proposed. The model is based on data from analyses of peculiarities of recombinant cells of this plague-causing agent carrying the cloned first Bg/II fragment of the Ca(2+)-dependence plasmid (pCaD) and a combination of this fragment and other plasmid pCaD fragments. The data obtained also allowed a revision of the role of the lcr GVH locus of pCaD in this phenomenon.
The bank of the HindIII, EcoRI and PstI fragments of Yersinia pestis Ca(2+)-dependence plasmid (pCaD) was constructed and used as molecular probes, combined with the restriction analysis to map pCaD. Experiments on laboratory animals showed two subfragments of the fifth HindIII fragment to impart virulence, invasiveness to the plasmidless avirulent strains of Y. pestis, Y. pseudotuberculosis and Escherichia coli, and the protective activity to Y. pestis clones, while the original fifth HindIII fragment possessed no such property.
Antigens coded by the Ca2(+)-dependance plasmid were found in the cultural medium, cytoplasm and outer membranes of the three monoplasmid (pCadV) strains of Yersinia pestis with the different basic properties. The presence of 20 mM of Mg2+ at least in the medium is necessary for optimal expression of these proteins. The existence of strain differences in the bacterial cells reaction to temperature, cultivation medium has been demonstrated. No difference in the pCad-dependent proteins was found in Yersinia pestis and the causative agents of pseudotuberculosis, enterocolitis.
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The plasmid pXO2 determining the capsule synthesis has been shown to be transfered into the cells of different strains of Bacillus anthracis (STI-1, Sterne, KM33, KM35) by the transducing bacteriophage CP54ant and by mobilization by pAM beta 1 replicon with the frequencies, consequently, n.10(-8) and n.10(-7). The optimal parameters for the selection of clones having acquired the pXO2 plasmid have been defined. Mobilization for conjugational transfer has been demonstrated for the plasmid pXO1 coding for the production of Bacillus anthracis toxin. The dramatic increase of virulence for white mice has been registered for Bacillus anthracis strains having acquired the pXO2 plasmid replicon.
Some properties of the structure of Y. pestis capsular antigen macromolecules have been studied. The aminoacid composition of F1 protein, the aminoacid sequence of the N-terminal fragment of antigen polipeptide chain were determined. Some peculiarities in the dissociation of capsular antigen macromolecules have been studied. The formation of the product resulting from unterminated thermodissociation of F1 protein oligomeric form, consisting of four subunits, has been registered. The aspects of F1 protein association are discussed.
Plasmid DNA was isolated from Yersinia pestis strains containing pesticin I or fraction I antigen and "mouse" toxin determinants. Specificity of DNA preparations was studied by using them for transformation of plague agent strains carrying no plasmids. pPstI plasmid (molecular weight 7,0-7,8 MD) encoded pesticin I, fibrinolysin and plasmacoagulase synthesis. Fraction I antigen and "mouse" toxin production determinants were borne on pFraI/Tox plasmid (molecular weight about 50 MD). The observation that some Y. pestis cultures, having lost the ability to synthesize one of pFraI/Tox products, still retained this plasmid in their cells, is regarded as an evidence for a complicated regulation of pFraI/Tox function.
The study of immunocomplexes obtained from antisera to the preparations of Y. pestis outer membranes and membrane proteins has revealed that outer membrane proteins are involved in the formation of the immunocomplex and belong to previously unknown Y. pestis EV antigens.
Dry live plague vaccine EB was examined under microscope; it appeared that in the mentioned preparation the bacterial cells were enclosed in the artificial sucrose-gelatin capsule of the stabilizer which apparently maintained the vital activity of the microorganisms in the state of anabiosis by forming a stable bond with the bacterial body.
There proved to be a serological similarity between the antigens of the human small intestine, the stomach and the liver, and the antigens of various cholera vibrio fractions. No antigenic similarity was revealed in examination of the heart and kidney. Heterogenous antigen was found not only in the somatic V. cholerae antigen, strain 569 (B), but also in the cholerogen-toxoid obtained from it. At present it is the most widespread prophylactic preparation.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
In the bacterial population, phenotypic variability plays a part of structural and functional subsystem that occupies a special place in the relations of heterogenic populations by performing an important adaptive function in the common system of ecological connections of parasitocenosis. At the same time regularly varying microorganism phenotypes act as an independent system that are closely related with the conditions of the niches occupied by the causative agent. Each subsystem as part of parasitocenosis is provided by its intrinsic adaptive mechanisms, which in combination ensures the stability of biocenosis based on self-regulation of evolutionarily established ecosystems. With the total complexity of parasitocenosis, the causative agent of plague is essential in forming its focus. For objective analysis of an epizootic process, it is necessary to include the established mechanisms of phenotypic variability of the causative agent of plague as a key link of the structural and functional interaction ecosystem that determines the mechanism of plague entozootics.
The paper reviews the hypotheses that explain the mechanism of plague enzooty in natural foci, which are based on a concept of a wide range of plague microbial variability. A comparative analysis of the parameters of variability in the experimentally obtained plague microbial strains and "atypical" natural isolates of the causative agent has led to the conclusion that the mechanism of adaptive variability is due to a phenotypic change in ontogenesis that reflects the philogenetic pathway of the adaptability of a plague microbe to constantly changing living conditions in the ecological niche assimilated by the causative agent.