Subversion of host cell actin microfilaments is the hallmark enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli infections. Both pathogens translocate trans-membrane receptor protein-translocated intimin (Tir), which links extracellular bacterium to cytoskeleton. While both converge on neural Wiskott-Aldrich syndrome protein (N-WASP), Tir-mediated accretion by EPEC EHEC differ in that Tir(EPEC) requires tyrosine phosphorylation adaptor Nck, whereas Tir(EHEC) not...

Enteropathogenic Escherichia coli (EPEC) induces a severe watery diarrhea responsible for several hundred thousand infant deaths each year by process correlated with the loss (effacement) of absorptive microvilli. Effacement is linked to locus enterocyte effacement pathogenicity island that encodes an “injection system,” “effector” proteins, and Intimin outer membrane protein. Here, we reveal ( i ) two-step process, ii requires cooperative action three injected effectors (Map, EspF, Tir) as...

Campylobacter jejuni is the foremost cause of bacterial-induced diarrhoeal disease worldwide. Although it well established that C. infection intestinal epithelia triggers host innate immune responses, mechanism(s) involved remain poorly defined. Innate immunity can be initiated by families structurally related pattern-recognition receptors (PRRs) recognize specific microbial signature motifs. Here, we demonstrated maximal induction epithelial responses during with live cells. In contrast...

Enteropathogenic E. coli (EPEC) is a major cause of diarrheal infant death in developing countries, and probiotic bacteria have been shown to provide health benefits gastrointestinal infections. In this study, we investigated the influence gut symbiont Lactobacillus reuteri on EPEC adherence human intestinal epithelium. Different host cell model systems including non-mucus-producing HT-29 mucus-producing LS174T epithelial lines as well small biopsies were used. Adherence L. cells was...

Enteropathogenic E. coli (EPEC) is a human pathogen that causes acute and chronic pediatric diarrhea. The hallmark of EPEC infection the formation attaching effacing (A/E) lesions in intestinal epithelium. Formation A/E mediated by genes located on pathogenicity island locus enterocyte effacement (LEE), which encode adhesin intimin, type III secretion system (T3SS) six effectors, including essential translocated intimin receptor (Tir). Seventeen additional effectors are encoded outside LEE,...

Shiga toxins (Stx) produced by Escherichia coli are associated with systemic complications such as haemolytic–uraemic syndrome. The mechanism of Stx translocation across the epithelial barrier is unknown human intestinal epithelium lacks receptor Gb3. In this study, we have examined interaction purified Stx1 and 2 Caco-2 (Gb3+) T84 (Gb3–) cell lines, determined effects on intestine using in vitro organ culture (IVOC). exposure caused inhibition protein synthesis apoptosis but not cells....

Although the bundle-forming pilus (BFP) of enteropathogenic Escherichia coli (EPEC) mediates microcolony formation on epithelial cells, adherence BFP-deficient mutants is significantly abrogated, but are still adherent due to presence intimin and possibly other adhesins. In this study we investigated contribution recently described E. common (ECP) overall properties EPEC. We found that ECP BFP structures can be simultaneously observed in course (between zero time 7 h during infection)...

Epidemiological studies point to the gut as a key reservoir of multidrug resistant Escherichia coli multilocus sequence type 131 (ST131), globally dominant pathogenic clone causing urinary tract and bloodstream infections. Here we report detailed investigation its intestinal lifestyle. Clinical ST131 isolates 1 fimbriae null mutants were assessed for colonization human epithelia in mouse models. Mouse tissue underwent histologic analysis pathology localization. Key findings corroborated...

Enterohaemorrhagic Escherichia coli (EHEC) is a major foodborne pathogen and tightly adheres to human colonic epithelium by forming attaching/effacing lesions. To reach the epithelial surface, EHEC must penetrate thick mucus layer protecting epithelium. In this study, we investigated how interacts with intestinal using mucin-producing LS174T colon carcinoma cells mucosal biopsies. The level of binding lesion formation in was higher compared mucin-deficient cell lines, initial adherence...

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) is an important foodborne pathogen causing gastroenteritis and more severe complications, such as hemorrhagic colitis hemolytic uremic syndrome. Pathology most pronounced in the colon, but to date there no direct clinical evidence showing EHEC binding colonic epithelium patients. In this study, we investigated adherence human colon by using vitro organ culture (IVOC) of biopsy samples polarized T84 carcinoma cells. We show for first time...

By applying density gradient electrophoresis (DGE) to human macrophages infected with Mycobacterium bovis BCG, we were able separate three different bacterial fractions representing arrested phagosomes, phagolysosomes and mycobacterial clumps. After further purification of the phagosomal population, found that isolated phagosomes containing live BCG in maturation as they exhibited only low amounts lysosomal glycoprotein LAMP-1 processing hydrolase cathepsin D was blocked. In addition, MHC...

In vitro organ culture (IVOC) represents a gold standard model to study enteropathogenic E. coli (EPEC) infection of human intestinal mucosa. However, the optimal examination bacterial-host cell interaction requires directional epithelial exposure, without serosal or cut surface stimulation. A polarized IVOC system (pIVOC) was developed in order overcome such limitations: apical EPEC produced negligible bacterial leakage via biopsy edges, resulted enhanced colonization compared with IVOC,...

Attaching and effacing (A/E) lesions actin polymerization, the hallmark of enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. (EHEC) Citrobacter rodentium (CR) infections, are dependent on effector Tir. Phosphorylation Tir(EPEC/CR) Y474/1 leads to recruitment Nck neural Wiskott-Aldrich syndrome protein (N-WASP) strong polymerization in cultured cells. also contains an Asn-Pro-Tyr (NPY(454/1)) motif, which triggers weak polymerization. In EHEC NPY(458) pathway is amplified by...

ABSTRACT Intestinal colonization by enteropathogenic and enterohemorrhagic Escherichia coli requires the locus of enterocyte effacement-encoded type III secretion system. We report that NleC NleD are translocated into host cells via this Deletion mutants induced attaching effacing lesions in vitro, while infection calves or lambs showed neither gene was required for colonization.

Tir, the translocated intimin receptor of enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC EHEC) Citrobacter rodentium, is into host cell by a filamentous type III secretion system. Epithelial culture has demonstrated that Tir tyrosine phosphorylation necessary for attaching effacing (A/E) lesion formation EPEC C. but not required EHEC O157:H7. Recent in vivo work on rodentium reported translocation, its phosphorylation, colonization mouse colon. In this study we investigated...

Intimin is an outer-membrane adhesin that essential for colonization of the host gastrointestinal tract by attaching and effacing pathogens including enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic E. (EHEC) Citrobacter rodentium (CR). The N-terminus intimin from different strains highly conserved while C-terminus, which harnesses active receptor-binding site, shows sequence antigenic polymorphism. This diversity was used to define a number distinct types, most common are alpha,...

Summary Advances in the understanding of pathogenesis enterohaemorrhagic Escherichia coli (EHEC) have greatly benefited from use human epithelial cell lines under aerobic conditions. However, target site EHEC infection, intestine, conditions are microaerobic. In our study we used polarized colon carcinoma cells a vertical diffusion chamber system to investigate influence reduced apical oxygen levels on colonization. While microaerobiosis did not affect integrity and barrier function, numbers...

Enteroaggregative E. coli (EAEC) are a major cause of diarrhoea worldwide. Due to their heterogeneity and carriage in healthy individuals, identification diagnostic virulence markers for pathogenic strains has been difficult. In this study, we have determined phenotypic genotypic differences between EAEC sequence types (STs) epidemiologically associated with asymptomatic (ST31) diarrhoeal disease (ST40). ST40 demonstrated significantly enhanced intestinal adherence, biofilm formation,...

Enterohemorrhagic E. coli (EHEC) is a human intestinal pathogen that causes hemorrhagic colitis and hemolytic uremic syndrome. No vaccines or specific therapies are currently available to prevent treat these infections. EHEC tightly attaches the epithelium by injecting intimin receptor Tir into host cell via type III secretion system (T3SS). In this project, we identified camelid single domain antibody (nanobody), named TD4, recognizes conserved epitope overlapping binding site of its...

Interactions of anaerobic gut bacteria, such as Clostridium difficile, with the intestinal mucosa have been poorly studied due to challenges in culturing anaerobes oxygen-requiring epithelium. Although colonization by C. difficile is a key determinant disease outcome, precise mechanisms mucosal attachment and spread remain unclear. Here, using human epithelial monolayers co-cultured within dual environment chambers, we demonstrate that adhesion cells accompanied gradual increase bacterial...

Typical enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. (EHEC) employ either Nck, TccP/TccP2, or Nck TccP/TccP2 pathways to activate the neuronal Wiskott-Aldrich syndrome protein (N-WASP) trigger actin polymerization in cultured cells. This phenotype is used as a marker for pathogenic potential of EPEC EHEC strains. In this paper we report that O125:H6, which represents large category strains, lacks ability utilize hence triggers vitro only inefficiently. However, show...