Vol 32, No 2 (2017)

Species Yersinia pestis includes two subspecies, pestis and microti. Strains of subsp. pestis were the cause of three plague pandemics. Strains of subsp. microti circulate in populations of rodents belonging to the genus Microtus and cause only rare endemic diseases in human beings that are not accompanied by human-to-human transmission. The existence of combined plague foci with strains from different genotypes, biovars, and even both the Y. pestis subspecies circulating in the same area, as well as periodic introductions of Y. pestis subsp. pestis strains into the foci from which only the strains of subsp. microti were isolated previously, require fast and reliable identification of strain subspecies for optimization of plague prevention and control. For differentiation of Y. pestis subspecies among themselves and against Y. pseudotuberculosis, we analyzed the DNA targets (YPDSF_3711 and opgG), selected the primers, and determined optimal concentrations of the components of the reaction mixture and temperature conditions of PCR. The suggested method allows identification according to the amplicon number and size of Y. pestis subsp. pestis (563 bp), two phylogenetic groups of subsp. microti (SNP-types 0.PE2, 0.PE3, 0.PE4, and 0.PE5, 583 and 426 bp; 0.PE7, 779, 515, and 358 bp), the progenitor of the plague microbe Y. pseudotuberculosis (779, 583, and 426 bp) and Y. similis (779 and 426 bp). The study was carried out on a representative set of strains from the State Research Center for Applied Microbiology and Biotechnology (http://obolensk.org/center/state-collection.htm) and nucleotide sequences deposited in the DDBJ/EMBL/GenBank. The study showed 100% specificity and sensitivity of the proposed method.

The Gram-positive bacterium Listeria monocytogenes is a facultative intracellular pathogen. The InlB protein is required for L. monocytogenes active invasion into epithelial cells. InlB interacts with the surface tyrosine kinase receptor c-Met. Activation of c-Met by its natural ligand, hepatocyte growth factor, induces intracellular signaling pathways and causes cell proliferation and/or migration. Interactions of InlB with c-Met in the course of infection activates the receptor and results in cytoskeleton rearrangement and bacterial uptake. In this study, we investigated the potential of the purified InlB protein as the c-Met ligand causing cell proliferation. Three distinct InlB variants have been compared. These variants were previously described in L. monocytogenes strains isolated from different sources. The variants were shown to be different in the induction of HEp-2 cell proliferation. In addition, the InlB variants differed in their potential to induce cytoskeleton rearrangements.

Comparative analysis of glucose fermentation in typical strains of V. cholerae biovar El Tor isolated in the Russian Federation in 1970–1990 and highly virulent strains of genovariants imported in 1993–2012 was carried out. It was demonstrated that glucose metabolism of V. cholerae biovar El Tor genovariants changed as a result of acquisition of classical CTX prophage (or only its ctxB gene) and a corresponding increase in virulence. A phenotypical manifestation of these changes is a lack of ability to grow on a minimal nutrient medium supplemented with 1% carbohydrate, as well as compromised capacity for acetoin fermentation in the course of the Voges–Proskauer test. Possible causes of the degraded glucose metabolism are associated with the presence of SNP in gene alsD that encodes acetolactate decarboxylase enzyme and is incorporated into als operon, which, in turn, is involved in acetoin generation, as well as with hyperexpression of regulatory protein AphA that controls acetoin biosynthesis.

Most of gene cassette arrays in this study are reported for the first time in Iran. These show the role of integrons in dissemination of resistance genes among clinical isolates of P. aeruginosa.