[A study on the taxonomy of soil amoebas from Caspian plague foci based on an analysis of ribosomal operon sequences].

The results of a study on the taxonomy and quantitative abundance of free-living amoebas in soil samples from the Russian plague foci of the northwestern Caspian steppe, the Caspian sand, and the Volga-Ural steppe are presented. Amoebas of the Willaertia and Hartmanella genera, as well as representatives of myxomycetes, were isolated from samples. From these, amoebas of the Acanthamoeba genus predominated and could be as abundantas 300000 cells per 1 g of soil. Sequencing of the 18S rRNA gene region showed that Acanthamoeba from the Volga-Ural steppe focus belonged to the A. castellanii species. Phylogenetic analysis confirmed that amoebas from two other Caspian foci belonged to the species of Acanthamoeba spp.

[The biofilm formation in Yersinia pestis strains isolated in Astrakhan region].

AIM: To study biofilm formation in strains of Yersinia pestis isolated in 2009 in Astrakhan region. MATERIALS AND METHODS: Study of biofilm formation was performed on abiotic surfaces as well as on cuticle of nematode Caenorhabditis elegans. Detection of genes was performed by PCR with specific primers. RESULTS: Study of phenotypic (fermentation of sugars and alcohols) as well as genetic (presence of plasmids, genes of chromosome region of pigmentation) characteristics of Y. pestis strains showed that they are typical for strains isolated in Astrakhan region. All isolated in 2009 strains formed well developed biofilm on abiotic surfaces and cuticle of C. elegans nematode. They contained genes of hms operon and regulatory genes hmsT and hmsP, which are necessary for formation of pigmented colonies on Congo red medium as well as biofilm on abiotic and biotic surfaces. CONCLUSION: Strains of Y. pestis isolated in 2009 in Astrakhan region formed well developed biofilm on different types of surfaces, which could facilitate their survival in complex parasitic biocenosis of plague natural focus.

[Structural and functional analysis of araN gene in the Yersinia pestis strains of various origin].

Structural and functional analysis of the araN gene involved in regulation of expression of diagnostically significant symptom (arabinose fermentation) was performed in the Yersinia pestis microorganism. Lack of arabinose fermentation in the Altai substrain, Hissar substrain, and Talas strains was shown to be due to solitary nucleotide insert into the araN gene. The insert is in the position 763 bp. The strains of the main, Caucasian, and Ulege substrains do not contain this mutation of the araN gene. The absence of the mutation correlates with ability to ferment arabinose.

[Molecular mechanisms of the plague pathogenic agent interaction with invertebrates].

Microbe Russian Anti-Plague Research Institute, Saratov, Russia The literature data and experimental results of the authors on the molecular basis of plague agent interaction with invertebrates are discussed. The details of the plague agent life cycle, its genome organization, and molecular genetic mechanisms of its survival in flea vector and on the nematode cuticule are discussed. The experimental data about the ability to form biofilms at abiotic and biotic surfaces in the Yersinia pestis strains of the main and non-main subspecies are presented. Mechanisms of horizontal and vertical transmission of plague agent are considered. The suggestion about participation of the new member in the complex parasitic biocenosis (nematode, vector parasite) is put forward.

[Study of ability to form biofilms in main and non-main subspecies of Yersinia pestis strains].

AIM: To compare biofilm formation in main and non-main subspecies of Yersinia pestis strains as well as in Yersinia pseudotuberculosis strains and to study influence of different genes on expression of this characteristic in different subspecies of Y. pestis. MATERIALS AND METHODS: Study of biofilm formation was performed bygrowing cultures on LB broth in polystyrene Petri dishes with subsequent staining of biofilms formed on the dishes' bottom with crystal violet as well as by electron microscopy. Pigment-sorption sign was detected on differential medium with Congo red. RESULTS: It was shown that the majority of Y. pestis strains and all strains of Y. pseudotuberculosis form well-expressed biofilms on abiotic surface. Formation of biofilms by Y. pestis strains is clearly correlateswith their ability to form pigmented colonies on solid medium with dyestuff. Genes which according to literature data are necessary for biofilm formation by Y. pestis and Y. pseudotuberculosis were found in genome of non-main species. CONCLUSION: Ability of Y. pestis strains belonging to main and non-main subspecies to form biofilm on abiotic surface was revealed.

[Effect of preparations of protein Yop encoded by Yersinia pestis calcium-dependence plasmid on mice]. / Deistvie na myshei preparatov belkov Yop, kodiruemykh plazmidoi kal'tsiizavisimosti Yersinia pestis.

The impact of the preparations of Y. pestis secreted proteins Yop (YopH-M, YopB, YopD-N, YopE) on mice immunized with 3 s.c. injections was studied. Though these proteins failed to protect the animals from plague, they stimulated the immunobiological transformation in the immunized animals. YopB and YopD-N were found to have the highest immunobiological activity with respect to mice. The preparation of YopB induced the production of the highest titers of specific antibodies and stimulated cell-mediated immune response. The injection of YopD-N to mice led to a considerable decrease in the proliferative capacity of splenocytes in vitro in response to stimulation with nonspecific mitogen ConA, as well as to pathological changes in the kidneys.

[Cloning of the locus encoding synthesis of an outer membrane protein (Omp2) of the calcium dependence plasmid of Yersinia pestis (Lehmann, Neumann)]. / Klonirovanie lokusa plazmidy kal'tsiizavisimosti Yersinia pestis (Lehmann, Neumann), kodiruiushchego sintez belka vneshnei membranyi (BVM2)

The genetic locus of Yersinia pestis encoding synthesis of a 46-kDa heat-inducible outer membrane protein (Omp2) was cloned into pBR322 plasmid. The Omp2 was shown to be analogous to previously described YopH and Yop2b proteins. The fifth HindIII fragment of 48-MDa calcium dependence plasmid pCad358 mediates production of 31- and 28-kDa proteins, irrespective of orientation of the insertion. A 31-kDa polypeptide seems to correspond to the YopJ described elsewhere. The maps of BamHI and HindIII of pCad358 region studied differed from those described for pCD1 plasmid of Y. pestis KIM. The products encoded by genes from the fragment cloned in the Pgm+ background give rise to considerable growth of Y. pestis within mouse peritoneal macrophages but were not sufficient to cause lethal infectious process.

[Expression of Yersinia pestis antigens encoded by the Ca2+-dependence plasmid]. / Ekspressiia antigenov chumnogo mikroba, kodiruemykh plazmidoi Ca2+-zavisimosti.

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.