Search Results (10)

Yersinia enterocolitica is a foodborne pathogen capable of biofilm formation and virulence modulation in response to environmental signals. Among these, glucose—present at physiologically relevant concentrations in the human body—may serve as a regulatory cue affecting infection-associated pathways, including those governed by the pYV virulence plasmid. Although the role of glucose has been investigated under host-mimicking conditions, its impact in non-host environments remains poorly understood. This study was designed to evaluate the glucose-dependent physiological responses of two isogenic Y. enterocolitica strains, KT0001 (pYV-negative) and KT0003 (pYV-positive), under non-host conditions (26 °C). Both strains were cultured in TYE medium containing 0–3% glucose. Comparative analyses were conducted under identical in vitro conditions to elucidate plasmid-associated phenotypic differences. Glucose elicited markedly divergent responses. In KT0001, growth remained unaffected; however, biofilm formation declined by 77.7%, accompanied by a 90% reduction in surface hydrophobicity, a 40% decrease in motility, and a 59% drop in intracellular cyclic AMP—suggesting classical carbon catabolite repression. Conversely, KT0003 exhibited 86% growth inhibition but maintained biofilm levels. This was associated with substantial extracellular polymeric substance induction (~20-fold increase in polysaccharides and ~4.7-fold in extracellular DNA) and nearly fivefold elevation in cyclic AMP levels, despite concurrent decreases in motility (64%) and hydrophobicity (40%). These findings indicate that glucose functions as a strain-specific modulator in Y. enterocolitica. In particular, KT0003’s response suggests that the pYV plasmid enables the bacterium to interpret glucose as a host-associated cue, even under non-host conditions, potentially initiating virulence-related adaptations prior to host contact. Full article

Background/Objectives: Yersinia enterocolitica is a pathogenic bacterium that forms biofilms, enhancing its persistence and resistance to antimicrobial agents. Biofilm formation in Y. enterocolitica is influenced by environmental factors such as temperature, calcium, and the presence of the virulence plasmid pYV. This study aims to explore how temperature, calcium, and pYV modulate biofilm formation in Y. enterocolitica, with a focus on motility and extracellular polymeric substance (EPS) production as key factors. Methods: Y. enterocolitica strains with and without the pYV plasmid were cultured at two different temperatures (26 °C and 37 °C). The effect of calcium (5 mM) on biofilm formation was tested at both temperatures. Biofilm formation was measured using crystal violet staining, motility was assessed using soft agar plates, and EPS production was quantified to determine its role in biofilm stabilization. Results: At 26 °C, biofilm formation increased in pYV-negative strains, driven primarily by motility and flagellar expression. In contrast, at 37 °C, pYV-positive strains showed strong biofilm formation despite reduced growth, with EPS production as the key stabilizing factor. Calcium modulated biofilm formation in a temperature-dependent manner: at 26 °C, 5 mM calcium modestly reduced biofilm formation in pYV-negative strains, while at 37 °C, it significantly suppressed both EPS production and biofilm formation by approximately 50% in pYV-positive strains. Conclusions: This study reveals a novel regulatory switch where temperature, calcium, and pYV modulate biofilm formation in Y. enterocolitica. These findings suggest that Y. enterocolitica can adapt between motility- and EPS-dominated biofilm strategies depending on environmental conditions. Understanding these mechanisms offers potential targets for controlling biofilm-related persistence in clinical and food safety contexts. Full article

Pathogenic Y. enterocolitica’s contamination of cheeks, tongues, and other pork meats at retail was assessed in 2023, over 9 months. A total of 111 samples of cheeks, 104 of tongues, and 160 of fresh meat were taken at retail from the 13 regions of mainland France. The level of contamination was 16.0%, with a higher contamination in tongues (39.4%), followed by cheeks (16.4%). Only one meat sample was contaminated. Of the 128 isolated strains, 97.6% were of the BT4 biotype. Depending on the method used to check the presence of the plasmid—yadA-PCR, CR-MOX testing, or sequencing—the results were not consistent for some strains, but most of the strains (≥ to 65%) had the virulent plasmid pYV. All the BT4 strains (except two strains) carried the sequence ST18; they were distributed in 54 cgMLST genotypes. The genetic diversity of the strains was very high, whatever the typing method used, including cgMLST, wgMLST, and cgSNP. There was higher contamination in tongues and cheeks, and lower contamination in meat, suggesting that the head deboning step is riskier than the evisceration step for contamination by pathogenic Y. enterocolitica. This pathogen remains a zoonotic agent of public health importance to be monitored in pigs. Full article

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease of the central nervous system (CNS) caused by reactivation of dormant JC polyomavirus (JCPyV). PML was mainly observed in immunocompromised individuals, such as HIV-positive patients, autoimmune disease patients, and cancer patients. Given that the presence of anti-JCPyV antibodies in serum is a risk indicator for PML development, it is essential to monitor anti-JCPyV antibody levels. In the present study, we established reporter-based single-infection neutralization assays for JCPyV and the genetically similar BK polyoma virus (BKPyV). We then confirmed the lack of cross-reactivity between the two viruses using test sera obtained from mice immunized with plasmids encoding the JCPyV or BKPyV capsid. Next, we compared neutralization antibody titers in sera from healthy donors, patients with multiple sclerosis (MS), and HIV-positive patients using an in-house enzyme-linked immunosorbent assay (ELISA) with JCPyV-like particles (virus-like particles; VLPs). A positive correlation was demonstrated between the neutralization titer (75% infectious concentration; IC75) against JCPyV and the antibody titer obtained by VLP-based JCPyV ELISA. This assay system may be applied to detect antibodies against other PyVs by generation of pseudoviruses using the respective capsid expression plasmids, and is expected to contribute to the surveillance of PyV as well as basic research on these viruses. Full article

Pathogenic bacteria recognize environmental cues to vary gene expression for host adaptation. Moving from ambient to host temperature, Yersinia enterocolitica responds by immediately repressing flagella synthesis and inducing the virulence plasmid (pYV)-encoded type III secretion system. In contrast, shifting from host to ambient temperature requires 2.5 generations to restore motility, suggesting a link to the cell cycle. We hypothesized that differential DNA methylation contributes to temperature-regulated gene expression. We tested this hypothesis by comparing single-molecule real-time (SMRT) sequencing of Y. enterocolitica DNA from cells growing exponentially at 22 °C and 37 °C. The inter-pulse duration ratio rather than the traditional QV scoring was the kinetic metric to compare DNA from cells grown at each temperature. All 565 YenI restriction sites were fully methylated at both temperatures. Among the 27,118 DNA adenine methylase (Dam) sites, 42 had differential methylation patterns, while 17 remained unmethylated regardless of the temperature. A subset of the differentially methylated Dam sites localized to promoter regions of predicted regulatory genes including LysR-type and PadR-like transcriptional regulators and a cyclic-di-GMP phosphodiesterase. The unmethylated Dam sites localized with a bias to the replication terminus, suggesting they were protected from Dam methylase. No cytosine methylation was detected at Dcm sites. Full article

Yersiniosis is the third most commonly reported foodborne zoonosis in the European Union. Here, we evaluated the prevalence of pathogenic Yersinia enterocolitica among healthy pigs (as a major reservoir) in a slaughterhouse in Bulgaria. A total of 790 tonsils and feces from 601 pigs were examined. Isolation and pathogenicity characterization was carried out by the ISO 10273:2003 protocol and Polymerase Chain Reaction (PCR), detecting the 16S rRNA gene, attachment and invasion locus (ail), Yersinia heat-stable enterotoxin (ystA), and Yersinia adhesion (yadA) genes. Genetic diversity was assessed by pulsed-field gel electrophoresis (PFGE), and antimicrobial resistance by the standard disk diffusion method. Of all the pigs tested, 6.7% were positive for Y. enterocolitica. All isolates belonged to Y. enterocolitica bioserotype 4/O:3. ail, and ystA genes were detected in all positive strains (n = 43), while the plasmid Yersinia virulence plasmid (pYV) was detected in 41. High homogeneity was observed among the strains, with all strains susceptible to ceftriaxone, amikacin and ciprofloxacin, and resistant to ampicillin. In conclusion, a low prevalence of Y. enterocolitica 4/O:3 was found in healthy pigs slaughtered in Bulgaria, not underestimating possible contamination of pork as a potential risk to consumer health. Full article

Yersinia enterocolitica and Y. pseudotuberculosis are important causes of enteric illness worldwide. Rapid response to suspected foodborne outbreaks is hampered by the widespread use of cold enrichment methods that require incubation periods of 10–21 days. Although these species grow faster at elevated temperatures, part of the rationale for cold enrichment is that a key pathogenicity marker (pYV virulence plasmid) is said to be lost at elevated temperatures. Experimental data on this claim seems scarce. We previously described an approach involving an enrichment step at 37 °C for Yersinia detection, applied this approach to additional strains, and examined the presence of plasmids in reisolates, as well as those recovered in our original study. Plasmids were recovered from every reisolate examined; the presence of marker genes yadA and virF denoted the virulence plasmid in 10 of the 11 strains examined. Use of an enrichment step at 37 °C does not appear to promote loss of the pYV or other plasmids harboured by foodborne pathogenic Y. enterocolitica and Y. pseudotuberculosis; wider adoption of this approach may assist the development of more rapid detection methods. Full article

Yersinia enterocolitica culture-positive rodents and shrews were reported in different territories across Georgia during 14 of 17 years of investigations conducted for the period of 1981–1997. In total, Y. enterocolitica was isolated from 2052 rodents (15 species) and 33 shrews. Most isolates were obtained from Microtus arvalis, Rattus norvegicus, Mus musculus, and Apodemus spp. During the prospective study (2017−2019), isolates of Yersinia-like bacteria were cultured from 53 rodents collected in four parts of Georgia. All the Yersinia-like isolates were confirmed as Y. enterocolitica based on the API 20E and the BD Phenix50 tests. Whole-genome (WG) sequencing of five rodents and one shrew strain of Y. enterocolitica revealed that they possessed a set of virulence genes characteristic of the potentially pathogenic strains of biogroup 1A. All isolates lacked distinguished virulence determinants for YstA, Ail, TccC, VirF, and virulence plasmid pYV but carried the genes for YstB, YmoA, HemPR-HmuVSTU, YaxAB, PhlA, PldA, ArsCBR, and a flagellar apparatus. One strain contained a gene highly homologous to heat-labile enterotoxin, a chain of E. coli, a function not previously described for Y. enterocolitica. The WG single-nucleotide polymorphism-based typing placed the isolates in four distinct phylogenetic clusters. Full article

Yersinia entercolitica is a bacterial species within the genus Yersinia, mostly known as a human enteric pathogen, but also recognized as a zoonotic agent widespread in domestic pigs. Findings of this bacterium in wild animals are very limited. The current report presents results of the identification of cultures of Y. entercolitica from dead bats after a massive bat die-off in a cave in western Georgia. The growth of bacterial colonies morphologically suspected as Yersinia was observed from three intestine tissues of 11 bats belonging to the Miniopterus schreibersii species. These three isolates were identified as Y. enterocolitica based on the API29 assay. No growth of Brucella or Francisella bacteria was observed from tissues of dead bats. Full genomes (a size between 4.6–4.7 Mbp) of the Yersinia strains isolated from bats were analyzed. The phylogenetic sequence analyses of the genomes demonstrated that all strains were nearly identical and formed a distinct cluster with the closest similarity to the environmental isolate O:36/1A. The bat isolates represent low-pathogenicity Biotype 1A strains lacking the genes for the Ail, Yst-a, Ysa, and virulence plasmid pYV, while containing the genes for Inv, YstB, and MyfA. Further characterization of the novel strains cultured from bats can provide a clue for the determination of the pathogenic properties of those strains. Full article

Pseudotuberculosis in humans until the 1950s was found in different countries of the world as a rare sporadic disease that occurred in the form of acute appendicitis and mesenteric lymphadenitis. In Russia and Japan, the Yersinia pseudotuberculosis (Y. pseudotuberculosis) infection often causes outbreaks of the disease with serious systemic inflammatory symptoms, and this variant of the disease has been known since 1959 as Far Eastern Scarlet-like Fever (FESLF). Russian researchers have proven that the FESLF pathogen is associated with a concrete clonal line of Y. pseudotuberculosis, characterized by a specific plasmid profile (pVM82, pYV 48 MDa), sequence (2ST) and yadA gene allele (1st allele). This review summarized the most important achievements in the study of FESLF since its discovery in the Far East. It has been established that the FESLF causative agent is characterized by a unique phenomenon of psychrophilicity, which consists of its ability to reproduce in the environment with its biologically low and variable temperature (4–12 °C), at which the pathogen multiplies and accumulates while maintaining or increasing its virulence, which ensures the emergence and development of the epidemic process. The key genetic and biochemical mechanisms of Y. pseudotuberculosis adaptation to changing environmental conditions were characterized, and the morphological manifestations of the adaptive variability of these bacteria in different conditions of their habitat were revealed. The main features of the pathogenesis and morphogenesis of FESLF, including those associated with the Y. pseudotuberculosis toxigenicity, were presented. The pathogenetic value of the plasmid PVM82, found only in the FESLF pathogen, was shown. Full article