Using the structural diversity of siderophore biosynthesis genes for intra-and interspecific differentiation of pathogenic yersinia

The paper analyzes the siderophore biosynthesis genes that are located in the ysu and ynp loci of only Y. pestis and Y. pseudotuberculosis, have variable structure between different strains of both species and contain previously unknown variable number tandem repeats (VNTR). The purpose of the study was to assess the possibility of using these VNTR as genetic markers for intra-and interspecific differentiation of pathogenic Yersinia. Based on the novel VNTR-markers, three pairs of primers (ysu-interF/R, ilp1F/R и ilp2F/R) were designed and used for the in silico and in vitro PCR analysis of various Y.pestis and Y. pseudotuberculosis strains. All studied Y. pestis strains of the main subspecies (ssp pestis), unlike the strains of non-main subspecies and Y. pseudotuberculosis, did not give amplicon with ilp1F/R primers, since the area between them contains an IS100 element. To identify the strains of the main subspecies, the fourth pair of primers ilp1F-is100R was designed, allowing the most dangerous ssp pestis strains to be distinguished from the not dangerous non-main ssp strains. Y. pseudotuberculosis strains were characterized by a significant variety of amplicons with three pairs of primers, and which made it possible to carry out intraspecies strain genotyping. At the same time, for those strains whose serotype is known, the correlation between the serogroup and the genotype of the strains was observed. Analysis of the 1 serotype strains representing most sequenced Y. pseudotuberculosis strains allowed us to separate two gene groups differing from the rest of 1 serotype gene groups. The first one included the serotype 1a strains isolated from people in Europe, which are known to have the greatest pathogenetic potential. The other one was formed by serotype 1b strains isolated from people in Siberia and Primorye, which are characterized by the high epidemic potential. Thus, four pairs of primers designed in this study can be used to develop additional tests for the identification and differential diagnostics of the most dangerous Y. pestis ssp pestis and Y. pseudotuberculosis serotype 1a and 1b strains.

Genome Scale Analysis Reveals IscR Directly and Indirectly Regulates Virulence Factor Genes in Pathogenic Yersinia

How bacteria adapt to the changing environment within the host is critical for their ability to survive and cause disease. For example, the mammalian host severely restricts iron availability to limit bacterial growth, referred to as nutritional immunity.

Heightened virulence of Yersinia is associated with decreased function of the YopJ protein

Despite the maintenance of YopP/J alleles throughout the human-pathogenic Yersinia lineage, the benefit of YopP/J-induced phagocyte death for Yersinia pathogenesis in animals is not obvious. To determine how sequence divergence of YopP/J has impacted Yersinia virulence, we examined protein polymorphisms in this Type III secreted effector protein across 17 Yersinia species, and tested the consequences of polymorphism in a murine model of sub-acute systemic yersiniosis. Our evolutionary analysis revealed that codon 177 has been subjected to positive selection - the Y. enterocolitica residue had been altered from a leucine to a phenylalanine in nearly all Y. pseudotuberculosis and Y. pestis strains examined. Despite being a minor change, as both leucine and phenylalanine have hydrophobic side chains, reversion of YopJF177 to the ancestral YopJL177 variant yielded a Y. pseudotuberculosis strain with enhanced cytotoxicity towards macrophages, consistent with previous findings. Surprisingly, expression of YopJF177L in the mildly attenuated ksgA- background rendered the strain completely avirulent in mice. Consistent with this hypothesis that YopJ activity indirectly relates to Yersinia pathogenesis in vivo, ksgA- strains lacking functional YopJ failed to kill macrophages but actually regained virulence in animals. Also, treatment with the anti-apoptosis drug suramin prevented YopJ-mediated macrophage cytotoxicity and enhanced Y. pseudotuberculosis virulence in vivo. Our results demonstrate that Yersinia-induced cell death is detrimental for bacterial pathogenesis in this animal model of illness, and indicate that positive selection has driven YopJ/P and Yersinia evolution towards diminished cytotoxicity and increased virulence, respectively.

Autophagy and Intracellular Membrane Trafficking Subversion by Pathogenic Yersinia Species

Yersinia pseudotuberculosis, Y. enterocolitica and Y. pestis are pathogenic bacteria capable of causing disease in humans by growing extracellularly in lymph nodes and during systemic infections. While the capacity of these bacteria to invade, replicate, and survive within host cells has been known for long, it is only in recent years that their intracellular stages have been explored in more detail. Current evidence suggests that pathogenic Yersinia are capable of activating autophagy in both phagocytic and epithelial cells, subverting autophagosome formation to create a niche supporting bacterial intracellular replication. In this review, we discuss recent results opening novel perspectives to the understanding of intimate host-pathogens interactions taking place during enteric yersiniosis and plague.

Adhesins of pathogenic Yersiniae

The genus Yersinia includes 26 species, three of which are pathogenic to humans: Yersinia enterocolitica and Yersinia pseudotuberculosis, which cause yersiniosis and pseudotuberculosis, infections with mainly gastrointestinal symptoms, and Yersinia pestis, the causative agent of plague. Pathogenic Yersiniae express proteins that mediate attachment to host cells, facilitate invasion or evasion of the host’s immune system, allowing pathogens to proliferate and spread within the host. In addition, these species, and Y. pestis serve as models for studying the evolution of pathogenicity factors in bacteria. The virulence of pathogenic Yersinia strains depends on the presence of molecules with adhesive properties in their outer membrane. Some of them, such as the YadA and Inv proteins of enteropathogenic species, as well as the pH 6 antigen of Y. pestis, have been adequately studied. However, the whole-genome sequencing has revealed many other adhesins present in these microorganisms, which functions are just under investigation. This review briefly summarizes current knowledge about Yersinia adhesins, their functions and their putative role in the infectious process. Particular attention is paid to one of the families of β-cylindrical proteins of the outer membrane of Yersinia, associated with the pathogenicity of bacteria, namely, autotransporter adhesins. Key words: adhesion, pathogenesis, pathogenic factor, Yersinia