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Miner MV, Rauch I. Why put yourself on a pedestal? The pathogenic role of the A/E pedestal. Infect Immun 2024; 92:e0048923. [PMID: 38591884 PMCID: PMC11384751 DOI: 10.1128/iai.00489-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024] Open
Abstract
Certain Escherichia coli (E. coli) strains are attaching and effacing (A/E) lesion pathogens that primarily infect intestinal epithelial cells. They cause actin restructuring and polymerization within the host cell to create an actin-rich protrusion below the site of adherence, termed the pedestal. Although there is clarity on the pathways initiating pedestal formation, the underlying purpose(s) of the pedestal remains ambiguous. The conservation of pedestal-forming activity across multiple pathogens and redundancy in formation pathways indicate a pathogenic advantage. However, few decisive conclusions have been drawn, given that the results vary between model systems. Some research argues that the pedestal increases the colonization capability of the bacterium. These studies utilize A/E pathogens specifically deficient in pedestal formation to evaluate adhesion and intestinal colonization following infection. There have been many proposed mechanisms for the colonization benefit conferred by the pedestal. One suggested benefit is that the pedestal allows for direct cytosolic anchoring through incorporation of the established host cortical actin, causing a stable link between the pathogen and cell structure. The pedestal may confer enhanced motility, as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) are better able to migrate on the surface of host cells and infect neighboring cells in the presence of the pedestal. Additionally, some research suggests that the pedestal improves effector delivery. This review will investigate the purpose of pedestal formation using evidence from recent literature and will critically evaluate the methodology and model systems. Most importantly, we will contextualize the proposed functions to reconcile potential synergistic effects.
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Affiliation(s)
- M V Miner
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - I Rauch
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
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Adorján A, Thuma Á, Könyves L, Tóth I. First isolation of atypical enteropathogenic Escherichia coli from geese (Anser anser domestica) and first description of atypical EPEC from turkeys and pigeons in Hungary. BMC Vet Res 2021; 17:263. [PMID: 34353312 PMCID: PMC8340449 DOI: 10.1186/s12917-021-02968-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 07/15/2021] [Indexed: 11/23/2022] Open
Abstract
Background Escherichia coli is a bacterial species widely distributed among mammals and avian species, and also a member of the normal intestinal microbiota. However, some E. coli strains of different pathotypes can cause disease in both humans and animals. Atypical enteropathogenic E. coli (aEPEC) can infect both animals and humans or influence the severity of other ongoing infections. Results In the present study, a total of 332 samples were collected from ducks, geese, turkeys, chickens, and pigeons from the Hungarian Veterinary Diagnostic Directorate, two slaughterhouses, two pigeon keepers and one backyard chicken farm. E. coli was isolated and verified from 319 samples. The isolates were screened by PCR for diarrheagenic E. coli pathotypes. Altogether seven atypical enteropathogenic E. coli (aEPEC) strains were identified: two from four-week-old dead turkeys, two from force-fed geese, and three from pigeons. No further pathotypes were identified in the collection. The atypical EPEC strains were classified phylogenetically to B1, B2, and F, and four out of the seven aEPEC isolates proved to be multidrug resistant. Serotypes of aEPEC strains were uniform collected from same farms and showed diversity between their origins with O76, O145, O109 serogroups. Conclusions This is the first report in the literature about aEPEC in goose (Anser anser domestica). Furthermore, this is the first isolation of aEPEC from turkeys and pigeons in Hungary. The uneven distribution of aEPEC in different age groups of poultry suggests that aEPEC disappears with growing up, but stress (e.g.: force-feeding) and concurrent diseases might promote its reappearance in the intestine.
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Affiliation(s)
- András Adorján
- Department of Microbiology and Infectious Diseases, University of Veterinary Medicine, Budapest, Hungary.
| | - Ákos Thuma
- Veterinary Diagnostic Directorate, National Food Chain Safety Office, Budapest, Hungary
| | - László Könyves
- Department of Animal Hygiene and Mobile Clinic, University of Veterinary Medicine, Budapest, Hungary
| | - István Tóth
- Institute for Veterinary Medical Research, Centre for Agricultural Research, Budapest, Hungary
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Vieira MA, Dias RCB, Dos Santos LF, Rall VLM, Gomes TAT, Hernandes RT. Diversity of strategies used by atypical enteropathogenic Escherichia coli to induce attaching and effacing lesion in epithelial cells. J Med Microbiol 2019; 68:940-951. [PMID: 31107199 DOI: 10.1099/jmm.0.000998] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
PURPOSE This study aimed to characterize 82 atypical enteropathogenic Escherichia coli (aEPEC) isolates, obtained from patients with diarrhea in Brazil, regarding their adherence patterns on HeLa cells and attaching and effacing (AE) lesion pathways. METHODOLOGY The adherence and fluorescence-actin staining (FAS) assays were performed using HeLa cells. AE lesion pathways were determined through the detection of tyrosine residue 474 (Y474) phosphorylation in the Tir protein, after its translocation to host cells, and by PCR assays for tir genotyping and detection of Tir-cytoskeleton coupling protein (tccP) genes. RESULTS Regarding the adherence pattern, determined in the presence of d-mannose, 12 isolates (14.6 %) showed the localized adherence (LA)-like pattern, 3 (3.7 %) the aggregative adherence pattern and 4 (4.9 %) a hybrid LA/diffuse adherence pattern. In addition, 36 (43.9 %) isolates displayed an undefined adherence, and 26 (31.7 %) were non-adherent (NA), while one (1.2 %) caused cell detachment. Among the 26 NA aEPEC isolates, 11 showed a type 1 pilus-dependent adherence in assays performed without d-mannose, while 15 remained NA. Forty-eight (58.5 %) aEPEC were able to trigger F-actin accumulation underneath adherent bacteria (FAS-positive), which is an important feature of AE lesions. The majority (58.3 %) of these used the Tir-Nck pathway, while 39.6 % may use both Tir-Nck and Tir-TccP pathways to induce AE lesions. CONCLUSION Our results reveal the diversity of strategies used by aEPEC isolates to interact with and damage epithelial host cells, thereby causing diarrheal diseases.
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Affiliation(s)
- Melissa A Vieira
- 1 Departamento de Microbiologia e Imunologia, Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
| | - Regiane C B Dias
- 1 Departamento de Microbiologia e Imunologia, Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
| | - Luís F Dos Santos
- 2 Centro de Bacteriologia, Instituto Adolfo Lutz (IAL), São Paulo SP, Brazil
| | - Vera L M Rall
- 1 Departamento de Microbiologia e Imunologia, Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
| | - Tânia A T Gomes
- 3 Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo (UNIFESP), São Paulo SP, Brazil
| | - Rodrigo T Hernandes
- 1 Departamento de Microbiologia e Imunologia, Instituto de Biociências, Universidade Estadual Paulista "Júlio de Mesquita Filho" (UNESP), Botucatu, SP, Brazil
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Arais LR, Barbosa AV, Andrade JRC, Gomes TAT, Asensi MD, Aires CAM, Cerqueira AMF. Zoonotic potential of atypical enteropathogenic Escherichia coli (aEPEC) isolated from puppies with diarrhoea in Brazil. Vet Microbiol 2018; 227:45-51. [PMID: 30473351 DOI: 10.1016/j.vetmic.2018.10.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 10/10/2018] [Accepted: 10/23/2018] [Indexed: 02/02/2023]
Abstract
Recent studies point atypical enteropathogenic Escherichia coli (aEPEC) to be an important agent in childhood diarrhoea in Brazil. aEPEC are commonly found in various animal species, including dogs. Although the true zoonotic risk remains unknown, some strains recovered from dogs present the same serotypes and carry the same virulence genes implicated in human disease. In this study, we compared the virulence and genetic relationship among a set of aEPEC strains previously isolated from diarrheic faeces from companion dogs and humans. A total of 17 strains, 12 from puppies and five from children, were studied. The strains were assessed for: (i) presence of virulence-associated genes (a total of 31 genes) using PCR assays; (ii) genetic relationship by Random Amplified Polymorphic DNA (RAPD), Multilocus Sequence Typing (MLST) and Pulsed-field Gel Electrophoresis (PFGE); and (iii) adherence pattern in intestinal Caco-2 cells. The occurrence of virulence genes was similar between the canine and human isolates presenting the same serotype. The fimbrial genes ecpA and fimH were the most frequently detected, followed by hcpA, tccP, tccP2, lpfA1, lpfA2, astA and toxB genes. Several nle genes were also detected, with one canine strain (O156:H- / ST327) showing all PAI O-122 genes investigated (efa-1, nleB, nleE and ent/espL2). Canine and human strains of the same serotype were grouped into a single cluster by RAPD and PFGE, in which the ST10 and ST206 were identified. Additionally, most of the strains exhibited a localized adherence-like phenotype when interacting with Caco-2 cells. The results showed that some canine aEPEC strains share virulence genes commonly found in human pathogenic strains. Moreover, strains of the same serotype, isolated from dogs and children, share virulence genes and are phylogenetically close, suggesting a potential zoonotic risk.
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Affiliation(s)
- Lavicie R Arais
- Laboratório de Enteropatógenos, Microbiologia Veterinária e de Alimentos, Universidade Federal Fluminense, Professor Hernani Melo Street, 101, Niterói, RJ, 24210-130, Brazil
| | - André V Barbosa
- Laboratório de Enteropatógenos, Microbiologia Veterinária e de Alimentos, Universidade Federal Fluminense, Professor Hernani Melo Street, 101, Niterói, RJ, 24210-130, Brazil.
| | - João R C Andrade
- Faculdade de Ciências Médicas, Departamento de Microbiologia, Imunologia e Parasitologia, Universidade do Estado do Rio de Janeiro. Prof., Manuel de Abreu Avenue, 444, Rio de Janeiro, RJ, 20550-170, Brazil
| | - Tânia A T Gomes
- Departamento de Microbiologia, Imunologia e Parasitologia, Escola Paulista de Medicina, Universidade Federal de São Paulo, Botucatu Street, 862, São Paulo, SP, 04023-062, Brazil
| | - Marise D Asensi
- Laboratório de Pesquisa em Infecção Hospitalar, Fundação Oswaldo Cruz, Brasil Avenue, 4365, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Caio A M Aires
- Laboratório de Pesquisa em Infecção Hospitalar, Fundação Oswaldo Cruz, Brasil Avenue, 4365, Rio de Janeiro, RJ, 21040-360, Brazil
| | - Aloysio M F Cerqueira
- Laboratório de Enteropatógenos, Microbiologia Veterinária e de Alimentos, Universidade Federal Fluminense, Professor Hernani Melo Street, 101, Niterói, RJ, 24210-130, Brazil
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Santos ECCD, Castro VS, Cunha-Neto A, Santos LFD, Vallim DC, Lisbôa RDC, Carvalho RCT, Junior CAC, Figueiredo EEDS. Escherichia coli O26 and O113:H21 on Carcasses and Beef from a Slaughterhouse Located in Mato Grosso, Brazil. Foodborne Pathog Dis 2018; 15:653-659. [PMID: 30036077 DOI: 10.1089/fpd.2018.2431] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Shiga toxin-producing Escherichia coli (STEC) is a group of emerging pathogens that can cause human diseases, including hemolytic uremic syndrome (HUS) and hemorrhagic colitis (HC). Monitoring slaughtering stages and checking contamination points are crucial for the production of safe food. In this context, the aim of this study was to verify contamination by STEC strains, to determine the contamination points and evaluate the resistance profile to 12 antimicrobials used in both veterinary and human medicine. A total of 80 samples were obtained from eight collection points (pen floor, rectum, hide, carcass swabs and esophagus, diaphragm, masseter, and retail beef tissue samples). The isolates were collected by dilution plating on MacConkey agar with sorbitol, cefixime, and tellurite and analyzed by multiplex polymerase chain reaction for virulence genes. Serotyping of non-O157 was performed, and testing for 12 antibiotics by disk diffusion was carried out. A total of 18 STEC strains were isolated, presenting different virulence profiles. Contamination by STEC was observed in the rectum (5/18), carcass surface (5/18), hide (3/18), diaphragm (2/18), retail beef (2/18), and masseter muscle (1/18). Pen floor swabs and esophagus tissues showed no STEC contamination. Moreover, three strains were identified as O26 and three as O113:H21 strains, which have been linked to HUS and HC outbreak cases in Brazil. All STEC isolates were susceptible to all evaluated antimicrobials, except streptomycin. The presence of STEC strains is a direct risk to the consumer, especially when isolated from retail beef, and contamination can occur during different slaughter stages. However, antimicrobial resistance profiles did not identify multidrug-resistant strains, limiting potential antimicrobial resistance transmission to other pathogens.
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Affiliation(s)
| | - Vinicius Silva Castro
- 2 Instituto de Química , Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Adelino Cunha-Neto
- 3 Programa de Pós graduação Nutrição, Alimentos e Metabolismo, Universidade Federal de Mato Grosso , Cuiabá, Brazil .,4 Faculdade de Veterinária, Universidade Federal Fluminense , Rio de Janeiro, Brazil
| | - Luis Fernando Dos Santos
- 5 Instituto Adolf Lutz , Núcleo de Doenças Entéricas e Infecções por Patógenos Especiais, São Paulo, Brazil
| | | | | | | | - Carlos Adam Conte Junior
- 2 Instituto de Química , Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil .,4 Faculdade de Veterinária, Universidade Federal Fluminense , Rio de Janeiro, Brazil .,6 Instituto Oswaldo Cruz , Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
| | - Eduardo Eustáquio de Souza Figueiredo
- 1 Programa de Pós graduação em Ciência Animal, Universidade Federal de Mato Grosso , Cuiabá, Brazil .,3 Programa de Pós graduação Nutrição, Alimentos e Metabolismo, Universidade Federal de Mato Grosso , Cuiabá, Brazil
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Martins FH, Nepomuceno R, Piazza RMF, Elias WP. Phylogenetic distribution of tir-cytoskeleton coupling protein (tccP and tccP2) genes in atypical enteropathogenic Escherichia coli. FEMS Microbiol Lett 2018; 364:3827361. [PMID: 28505295 DOI: 10.1093/femsle/fnx101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 05/12/2017] [Indexed: 12/21/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) strains employ the type III secretion system (T3SS) effector Tir to induce actin cytoskeletal rearrangements. While some EPEC require tyrosine phosphorylation (Y-P) of Tir to trigger actin assembling, certain strains whose Tir is not tyrosine phosphorylated utilize the T3SS effector Tir-cytoskeleton coupling protein (TccP/TccP2) for efficient actin polymerization. The presence of tccP/tccP2 in typical EPEC belonging to distinct evolutionary lineages is well established but, in contrast, little is known about the distribution of these genes in atypical EPEC (aEPEC) showing distinct phylogenetic background. In this study, we screened 72 pathogenic aEPEC for the presence of tccP/tccP2 genes, and further characterized positive strains regarding tir type, phylogroups and production of TccP/TccP2. The tccP and/or tccP2 genes were detected in 45.8% of the strains, with a predominance of tccP2 allele. Most of these strains carried tirY-P, suggesting that can trigger actin polymerization using both Tir tyrosine phosphorylation and TccP/TccP2 pathways. aEPEC strains carrying tccP or tccP2 were significantly associated to phylogroups E and B1, respectively. We also observed a strain-to-strain variation regarding TccP/TccP2 production. Our results demonstrate a wide distribution of tccP/tccP2 genes among pathogenic aEPEC strains, as well associations between specific alleles and phylogenetic backgrounds.
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Affiliation(s)
- Fernando H Martins
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP 05503-900, Brazil
| | - Roberto Nepomuceno
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP 05503-900, Brazil
| | - Roxane M F Piazza
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP 05503-900, Brazil
| | - Waldir P Elias
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP 05503-900, Brazil
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7
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Martins FH, Guth BEC, Piazza RMF, Elias WP, Leão SC, Marzoa J, Dahbi G, Mora A, Blanco M, Blanco J, Pelayo JS. Lambs are an important source of atypical enteropathogenic Escherichia coli in southern Brazil. Vet Microbiol 2016; 196:72-77. [PMID: 27939159 DOI: 10.1016/j.vetmic.2016.10.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 07/07/2016] [Accepted: 10/09/2016] [Indexed: 12/16/2022]
Abstract
Food-producing animals can harbor Escherichia coli strains with potential to cause diseases in humans. In this study, the presence of enteropathogenic E. coli (EPEC) was investigated in fecal samples from 130 healthy sheep (92 lambs and 38 adults) raised for meat in southern Brazil. EPEC was detected in 19.2% of the sheep examined, but only lambs were found to be positive. A total of 25 isolates was characterized and designated atypical EPEC (aEPEC) as tested negative for bfpA gene and BFP production. The presence of virulence markers linked to human disease as ehxA, paa, and lpfAO113 was observed in 60%, 24%, and 88% of the isolates, respectively. Of the 11 serotypes identified, eight were described among human pathogenic strains, while three (O1:H8, O11:H21 and O125:H19) were not previously detected in aEPEC. Associations between intimin subtypes and phylogroups were observed, including eae-θ2/A, eae-β1/B1, eae-α2/B2 and eae-γ1/D. Although PFGE typing of 16 aEPEC isolates resulted in 14 unique pulsetypes suggesting a genetic diversity, specific clones were found to be distributed in some flocks. In conclusion, potentially pathogenic aEPEC strains are present in sheep raised for meat, particularly in lambs, which can better contribute to dissemination of these bacteria than adult animals.
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Affiliation(s)
- Fernando H Martins
- Departamento de Microbiologia, Universidade Estadual de Londrina, Londrina, PR, Brazil
| | - Beatriz E C Guth
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Roxane M F Piazza
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
| | - Waldir P Elias
- Laboratório de Bacteriologia, Instituto Butantan, São Paulo, SP, Brazil
| | - Sylvia C Leão
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Juan Marzoa
- Laboratorio de Referencia de E. coli, Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Ghizlane Dahbi
- Laboratorio de Referencia de E. coli, Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Azucena Mora
- Laboratorio de Referencia de E. coli, Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Miguel Blanco
- Laboratorio de Referencia de E. coli, Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Jorge Blanco
- Laboratorio de Referencia de E. coli, Departamento de Microbioloxía e Parasitoloxía, Facultade de Veterinaria, Universidade de Santiago de Compostela, Lugo, Spain
| | - Jacinta S Pelayo
- Departamento de Microbiologia, Universidade Estadual de Londrina, Londrina, PR, Brazil.
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The Locus of Enterocyte Effacement and Associated Virulence Factors of Enterohemorrhagic Escherichia coli. Microbiol Spectr 2016; 2:EHEC-0007-2013. [PMID: 26104209 DOI: 10.1128/microbiolspec.ehec-0007-2013] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subset of Shiga toxin-producing Escherichia coli strains, termed enterohemorrhagic E. coli (EHEC), is defined in part by the ability to produce attaching and effacing (A/E) lesions on intestinal epithelia. Such lesions are characterized by intimate bacterial attachment to the apical surface of enterocytes, cytoskeletal rearrangements beneath adherent bacteria, and destruction of proximal microvilli. A/E lesion formation requires the locus of enterocyte effacement (LEE), which encodes a Type III secretion system that injects bacterial proteins into host cells. The translocated proteins, termed effectors, subvert a plethora of cellular pathways to the benefit of the pathogen, for example, by recruiting cytoskeletal proteins, disrupting epithelial barrier integrity, and interfering with the induction of inflammation, phagocytosis, and apoptosis. The LEE and selected effectors play pivotal roles in intestinal persistence and virulence of EHEC, and it is becoming clear that effectors may act in redundant, synergistic, and antagonistic ways during infection. Vaccines that target the function of the Type III secretion system limit colonization of reservoir hosts by EHEC and may thus aid control of zoonotic infections. Here we review the features and functions of the LEE-encoded Type III secretion system and associated effectors of E. coli O157:H7 and other Shiga toxin-producing E. coli strains.
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Actin pedestal formation by enterohemorrhagic Escherichia coli enhances bacterial host cell attachment and concomitant type III translocation. Infect Immun 2014; 82:3713-22. [PMID: 24958711 DOI: 10.1128/iai.01523-13] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Attachment of enterohemorrhagic Escherichia coli (EHEC) to intestinal epithelial cells is critical for colonization and is associated with localized actin assembly beneath bound bacteria. The formation of these actin "pedestals" is dependent on the translocation of effectors into mammalian cells via a type III secretion system (T3SS). Tir, an effector required for pedestal formation, localizes in the host cell plasma membrane and promotes attachment of bacteria to mammalian cells by binding to the EHEC outer surface protein Intimin. Actin pedestal formation has been shown to foster intestinal colonization by EHEC in some animal models, but the mechanisms responsible for this remain undefined. Investigation of the role of Tir-mediated actin assembly promoting host cell binding is complicated by other, potentially redundant EHEC-encoded binding pathways, so we utilized cell binding assays that specifically detect binding mediated by Tir-Intimin interaction. We also assessed the role of Tir-mediated actin assembly in two-step assays that temporally segregated initial translocation of Tir from subsequent Tir-Intimin interaction, thereby permitting the distinction of effects on translocation from effects on cell attachment. In these experimental systems, we compromised Tir-mediated actin assembly by chemically inhibiting actin assembly or by infecting mammalian cells with EHEC mutants that translocate Tir but are specifically defective in Tir-mediated pedestal formation. We found that an inability of Tir to promote actin assembly resulted in a significant and striking decrease in bacterial binding mediated by Tir and Intimin. Bacterial mutants defective for pedestal formation translocated type III effectors to mammalian cells with reduced efficiency, but the decrease in translocation could be entirely accounted for by the decrease in host cell attachment.
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Mallick EM, Garber JJ, Vanguri VK, Balasubramanian S, Blood T, Clark S, Vingadassalom D, Louissaint C, McCormick B, Snapper SB, Leong JM. The ability of an attaching and effacing pathogen to trigger localized actin assembly contributes to virulence by promoting mucosal attachment. Cell Microbiol 2014; 16:1405-24. [PMID: 24780054 DOI: 10.1111/cmi.12302] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 04/09/2014] [Accepted: 04/13/2014] [Indexed: 12/30/2022]
Abstract
Enterohaemorrhagic Escherichia coli (EHEC) colonizes the intestine and causes bloody diarrhoea and kidney failure by producing Shiga toxin. Upon binding intestinal cells, EHEC triggers a change in host cell shape, generating actin 'pedestals' beneath bound bacteria. To investigate the importance of pedestal formation to disease, we infected genetically engineered mice incapable of supporting pedestal formation by an EHEC-like mouse pathogen, or wild type mice with a mutant of that pathogen incapable of generating pedestals. We found that pedestal formation promotes attachment of bacteria to the intestinal mucosa and vastly increases the severity of Shiga toxin-mediated disease.
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Affiliation(s)
- Emily M Mallick
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA, 01655, USA
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Reiland HA, Omolo MA, Johnson TJ, Baumler DJ. A Survey of <i>Escherichia coli</i> O157:H7 Virulence Factors: The First 25 Years and 13 Genomes. ACTA ACUST UNITED AC 2014. [DOI: 10.4236/aim.2014.47046] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Lai Y, Rosenshine I, Leong JM, Frankel G. Intimate host attachment: enteropathogenic and enterohaemorrhagic Escherichia coli. Cell Microbiol 2013; 15:1796-808. [PMID: 23927593 PMCID: PMC4036124 DOI: 10.1111/cmi.12179] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 06/19/2013] [Accepted: 07/01/2013] [Indexed: 12/30/2022]
Abstract
Enteropathogenic and enterohaemorrhagic Escherichia coli use a novel infection strategy to colonize the gut epithelium, involving translocation of their own receptor, Tir, via a type III secretion system and subsequent formation of attaching and effecting (A/E) lesions. Following integration into the host cell plasma membrane of cultured cells, and clustering by the outer membrane adhesin intimin, Tir triggers multiple actin polymerization pathways involving host and bacterial adaptor proteins that converge on the host Arp2/3 actin nucleator. Although initially thought to be involved in A/E lesion formation, recent data have shown that the known Tir-induced actin polymerization pathways are dispensable for this activity, but can play other major roles in colonization efficiency, in vivo fitness and systemic disease. In this review we summarize the roadmap leading from the discovery of Tir, through the different actin polymerization pathways it triggers, to our current understanding of their physiological functions.
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Affiliation(s)
- YuShuan Lai
- Department of Microbiology and Physiological Systems, University of
Massachusetts Medical School, Worcester MA, USA
| | - Ilan Rosenshine
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of
Medicine, The Hebrew University of Jerusalem, Israel
| | - John M. Leong
- Department of Microbiology and Physiological Systems, University of
Massachusetts Medical School, Worcester MA, USA
- Molecular Biology and Microbiology Department, Tufts University,
Boston MA, USA
| | - Gad Frankel
- MRC Centre for Molecular Bacteriology and Infection, Imperial
College London, London, UK
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Tomat D, Migliore L, Aquili V, Quiberoni A, Balagué C. Phage biocontrol of enteropathogenic and shiga toxin-producing Escherichia coli in meat products. Front Cell Infect Microbiol 2013; 3:20. [PMID: 23761050 PMCID: PMC3674477 DOI: 10.3389/fcimb.2013.00020] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Accepted: 05/22/2013] [Indexed: 11/13/2022] Open
Abstract
Ten bacteriophages were isolated from faeces and their lytic effects assayed on 103 pathogenic and non-pathogenic Enterobacteriaceae. Two phages (DT1 and DT6) were selected based on their host ranges, and their lytic effects on pathogenic E. coli strains inoculated on pieces of beef were determined. We evaluated the reductions of viable cells of Escherichia coli O157:H7 and non-O157 Shiga toxigenic E. coli strains on meat after exposure to DT6 at 5 and 24°C for 3, 6, and 24 h and the effect of both phages against an enteropathogenic E. coli strain. Significant viable cell reductions, compared to controls without phages, at both temperatures were observed, with the greatest decrease taking place within the first hours of the assays. Reductions were also influenced by phage concentration, being the highest concentrations, 1.7 × 1010 plaque forming units per milliliter (PFU/mL) for DT1 and 1.4 × 1010 PFU/mL for DT6, the most effective. When enteropathogenic E. coli and Shiga toxigenic E. coli (O157:H7) strains were tested, we obtained viable cell reductions of 0.67 log (p = 0.01) and 0.77 log (p = 0.01) after 3 h incubation and 0.80 log (p = 0.01) and 1.15 log (p = 0.001) after 6 h. In contrast, all nonpathogenic E. coli strains as well as other enterobacteria tested were resistant. In addition, phage cocktail was evaluated on two strains and further reductions were observed. However, E. coli bacteriophage insensitive mutants (BIMs) emerged in meat assays. BIMs isolated from meat along with those isolated by using the secondary culture method were tested to evaluate resistance phenotype stability and reversion. They presented low emergence frequencies (6.5 × 10−7–1.8 × 10−6) and variable stability and reversion. Results indicate that isolated phages were stable on storage, negative for all the virulence factors assayed, presented lytic activity for different E. coli virotypes and could be useful in reducing Shiga toxigenic E. coli and enteropathogenic E. coli viable cells in meat products.
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Affiliation(s)
- David Tomat
- Área de Bacteriología, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario Rosario, Argentina.
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Abstract
Enteric Escherichia coli (E. coli) are both natural flora of humans and important pathogens causing significant morbidity and mortality worldwide. Traditionally enteric E. coli have been divided into 6 pathotypes, with further pathotypes often proposed. In this review we suggest expansion of the enteric E. coli into 8 pathotypes to include the emerging pathotypes of adherent invasive E. coli (AIEC) and Shiga-toxin producing enteroaggregative E. coli (STEAEC). The molecular mechanisms that allow enteric E. coli to colonize and cause disease in the human host are examined and for two of the pathotypes that express a type 3 secretion system (T3SS) we discuss the complex interplay between translocated effectors and manipulation of host cell signaling pathways that occurs during infection.
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Affiliation(s)
- Abigail Clements
- Centre for Molecular Microbiology and Infection, Imperial College, London, UK.
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Ogura Y. [Genomic analyses of mechanisms of virulence evolution in enterohemorrhagic E. coli and enteropathogenic E. coli]. Nihon Saikingaku Zasshi 2011; 66:175-86. [PMID: 21952352 DOI: 10.3412/jsb.66.175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yoshitoshi Ogura
- Frontier Science Research Center, University of Miyazaki, Miyazaki, Japan
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Bardiau M, Labrozzo S, Mainil JG. Study of polymorphisms in tir, eae and tccP2 genes in enterohaemorrhagic and enteropathogenic Escherichia coli of serogroup O26. BMC Microbiol 2011; 11:124. [PMID: 21624114 PMCID: PMC3119187 DOI: 10.1186/1471-2180-11-124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 05/30/2011] [Indexed: 11/10/2022] Open
Abstract
Background Enteropathogenic (EPEC) and enterohaemorrhagic (EHEC) Escherichia coli are responsible for food poisoning (enteritis and enterotoxaemia) in humans in developed countries. Cattle are considered to be an important reservoir of EHEC and EPEC strains for humans. Moreover, some of the strains, belonging to the O26, O111, O118 serogroups, for example, are also responsible for digestive disorders in calves. The Translocated intimin receptor (Tir), the intimin (Eae) and the Tir-cytoskeleton coupling protein (TccP) represent three virulence factors implicated in the intimate attachment of the bacteria to the eukaryotic cell. Major variants have already been described for these genes among the different serogroups but minor variations have not often been studied. In this study, we examined the polymorphisms of the tir, eae and tccP2 genes of O26 strains (EPEC and EHEC isolated from bovines and from humans) with the aim to determine whether these polymorphisms are host specific or not. Results Of the 70 tested strains, 10 strains (14% of the strains) presented one or several polymorphisms in the tir and eae genes, which have never previously been described. Concerning tccP2 detection, 47 of the 70 strains (67% of the strains) were found to be positive for this gene. Most of the strains were found to possess tccP2 variants described in strains of serogroup O26. Nevertheless, three strains had tccP2 genes respectively described in strains of serogroup O111, O103 and O55. Moreover, none of the polymorphisms was statistically specific to the bovine or the human isolates. Nevertheless, the two major variants of tccP2 were statistically associated with the pathotype (EPEC or EHEC). Conclusions In conclusion, tir and eae gene polymorphisms were found not to be numerous and not to be predominantly synonymous. Moreover, no difference was observed between human and bovine strains regarding the presence of polymorphisms. Finally, some tccP2 variants appeared to be pathotype specific. Further investigations need to be performed on a larger number of strains in order to confirm this specificity.
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Affiliation(s)
- Marjorie Bardiau
- Bacteriology, Department of Infectious and Parasitic Diseases, Veterinary Faculty, University of Liège, Liège B4000, Belgium
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17
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Wong ARC, Pearson JS, Bright MD, Munera D, Robinson KS, Lee SF, Frankel G, Hartland EL. Enteropathogenic and enterohaemorrhagic Escherichia coli: even more subversive elements. Mol Microbiol 2011; 80:1420-38. [PMID: 21488979 DOI: 10.1111/j.1365-2958.2011.07661.x] [Citation(s) in RCA: 256] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alexander R C Wong
- Centre for Molecular Microbiology and Infection, Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
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18
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Madic J, de Garam CP, Brugère H, Loukiadis E, Fach P, Jamet E, Auvray F. Duplex real-time PCR detection of type III effector tccP and tccP2 genes in pathogenic Escherichia coli and prevalence in raw milk cheeses. Lett Appl Microbiol 2011; 52:538-45. [DOI: 10.1111/j.1472-765x.2011.03038.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Atypical enteropathogenic Escherichia coli that contains functional locus of enterocyte effacement genes can be attaching-and-effacing negative in cultured epithelial cells. Infect Immun 2011; 79:1833-41. [PMID: 21343354 DOI: 10.1128/iai.00693-10] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) induces a characteristic histopathology on enterocytes known as the attaching-and-effacing (A/E) lesion, which is triggered by proteins encoded by the locus of enterocyte effacement (LEE). EPEC is currently classified as typical EPEC (tEPEC) and atypical EPEC (aEPEC), based on the presence or absence of the EPEC adherence factor plasmid, respectively. Here we analyzed the LEE regions of three aEPEC strains displaying the localized adherence-like (LAL), aggregative adherence (AA), and diffuse adherence (DA) patterns on HEp-2 cells as well as one nonadherent (NA) strain. The adherence characteristics and the ability to induce A/E lesions were investigated with HeLa, Caco-2, T84, and HT29 cells. The adherence patterns and fluorescent actin staining (FAS) assay results were reproducible with all cell lines. The LEE region was structurally intact and functional in all strains regardless of their inability to cause A/E lesions. An EspF(U)-expressing plasmid (pKC471) was introduced into all strains, demonstrating no influence of this protein on either the adherence patterns or the capacity to cause A/E of the adherent strains. However, the NA strain harboring pKC471 expressed the LAL pattern and was able to induce A/E lesions on HeLa cells. Our data indicate that FAS-negative aEPEC strains are potentially able to induce A/E in vivo, emphasizing the concern about this test for the determination of aEPEC virulence. Also, the presence of EspF(U) was sufficient to provide an adherent phenotype for a nonadherent aEPEC strain via the direct or indirect activation of the LEE4 and LEE5 operons.
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Crepin VF, Girard F, Schüller S, Phillips AD, Mousnier A, Frankel G. Dissecting the role of the Tir:Nck and Tir:IRTKS/IRSp53 signalling pathways in vivo. Mol Microbiol 2009; 75:308-23. [PMID: 19889090 PMCID: PMC2814079 DOI: 10.1111/j.1365-2958.2009.06938.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Attaching and effacing (A/E) lesions and actin polymerization, the hallmark of enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and Citrobacter rodentium (CR) infections, are dependent on the effector Tir. Phosphorylation of TirEPEC/CR Y474/1 leads to recruitment of Nck and neural Wiskott–Aldrich syndrome protein (N-WASP) and strong actin polymerization in cultured cells. TirEPEC/CR also contains an Asn-Pro-Tyr (NPY454/1) motif, which triggers weak actin polymerization. In EHEC the NPY458 actin polymerization pathway is amplified by TccP/EspFU, which is recruited to Tir via IRSp53 and/or insulin receptor tyrosine kinase substrate (IRTKS). Here we used C. rodentium to investigate the different Tir signalling pathways in vivo. Following infection with wild-type C. rodentium IRTKS, but not IRSp53, was recruited to the bacterial attachment sites. Similar results were seen after infection of human ileal explants with EHEC. Mutating Y471 or Y451 in TirCR abolished recruitment of Nck and IRTKS respectively, but did not affect recruitment of N-WASP or A/E lesion formation. This suggests that despite their crucial role in actin polymerization in cultured cells the Tir:Nck and Tir:IRTKS pathways are not essential for N-WASP recruitment or A/E lesion formation in vivo. Importantly, wild-type C. rodentium out-competed the tir tyrosine mutants during mixed infections. These results uncouple the Tir:Nck and Tir:IRTKS pathways from A/E lesion formation in vivo but assign them an important in vivo role.
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Affiliation(s)
- Valérie F Crepin
- Centre for Molecular Microbiology and Infection, Division of Cell and Molecular Biology, Imperial College London, London, UK.
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21
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Bruant G, Zhang Y, Garneau P, Wong J, Laing C, Fairbrother JM, Gannon VPJ, Harel J. Two distinct groups of porcine enteropathogenic Escherichia coli strains of serogroup O45 are revealed by comparative genomic hybridization and virulence gene microarray. BMC Genomics 2009; 10:402. [PMID: 19709428 PMCID: PMC2749873 DOI: 10.1186/1471-2164-10-402] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 08/26/2009] [Indexed: 11/14/2022] Open
Abstract
Background Porcine enteropathogenic Escherichia coli (PEPEC) strains of serogroup O45 cause post-weaning diarrhea and produce characteristic attaching and effacing (A/E) lesions. Most O45 PEPEC strains possess the locus of enterocyte effacement (LEE), encoding the virulence factors required for production of A/E lesions, and often possess the paa gene, which is thought to contribute to the early stages of PEPEC pathogenicity. In this study, nine O45 PEPEC strains and a rabbit enteropathogenic (REPEC) strain, known to produce A/E lesions in vivo, were characterized using an E. coli O157-E. coli K12 whole genome microarray and a virulence gene-specific microarray, and by PCR experiments. Results Based on their virulence gene profiles, the 10 strains were considered to be atypical EPEC. The differences in their genomes pointed to the identification of two distinct evolutionary groups of O45 PEPEC, Groups I and II, and provided evidence for a contribution of these genetic differences to their virulence in pigs. Group I included the REPEC strain and four O45 PEPEC strains known to induce severe A/E lesions in challenged pigs whereas Group II was composed of the five other O45 PEPEC strains, which induced less severe or no A/E lesions in challenged pigs. Significant differences between Groups I and II were found with respect to the presence or absence of 50 O-Islands (OIs) or S-loops and 13 K-islands (KIs) or K-loops, including the virulence-associated islands OI#1 (S-loop#1), OI#47 (S-loop#71), OI#57 (S-loop#85), OI#71 (S-loop#108), OI#115, OI#122, and OI#154 (S-loop#253). Conclusion We have genetically characterized a collection of O45 PEPEC strains and classified them into two distinct groups. The differences in their virulence gene and genomic island content may influence the pathogenicity of O45 PEPEC strains, and explain why Group I O45 PEPEC strains induced more severe A/E lesions in explants and challenged pigs than Group II strains.
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Affiliation(s)
- Guillaume Bruant
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de médecine vétérinaire, Université de Montréal, 3200 rue Sicotte, Saint-Hyacinthe, Québec J2S 7C6, Canada.
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Virulence genes and molecular typing of different groups of Escherichia coli O157 strains in cattle. Appl Environ Microbiol 2009; 75:6282-91. [PMID: 19684174 DOI: 10.1128/aem.00873-09] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Characterization of an Escherichia coli O157 strain collection (n = 42) derived from healthy Hungarian cattle revealed the existence of diverse pathotypes. Enteropathogenic E. coli (EPEC; eae positive) appeared to be the most frequent pathotype (n = 22 strains), 11 O157 strains were typical enterohemorrhagic E. coli (EHEC; stx and eae positive), and 9 O157 strains were atypical, with none of the key stx and eae virulence genes detected. EHEC and EPEC O157 strains all carried eae-gamma, tir-gamma, tccP, and paa. Other virulence genes located on the pO157 virulence plasmid and different O islands (O island 43 [OI-43] and OI-122), as well as espJ and espM, also characterized the EPEC and EHEC O157 strains with similar frequencies. However, none of these virulence genes were detected by PCR in atypical O157 strains. Interestingly, five of nine atypical O157 strains produced cytolethal distending toxin V (CDT-V) and carried genes encoding long polar fimbriae. Macro-restriction fragment enzyme analysis (pulsed-field gel electrophoresis) revealed that these E. coli O157 strains belong to four main clusters. Multilocus sequence typing analysis revealed that five housekeeping genes were identical in EHEC and EPEC O157 strains but were different in the atypical O157 strains. These results suggest that the Hungarian bovine E. coli O157 strains represent at least two main clones: EHEC/EPEC O157:H7/NM (nonmotile) and atypical CDT-V-producing O157 strains with H antigens different from H7. The CDT-V-producing O157 strains represent a novel genogroup. The pathogenic potential of these strains remains to be elucidated.
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Modelling of infection by enteropathogenic Escherichia coli strains in lineages 2 and 4 ex vivo and in vivo by using Citrobacter rodentium expressing TccP. Infect Immun 2009; 77:1304-14. [PMID: 19188355 DOI: 10.1128/iai.01351-08] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) strains colonize the human gut mucosa via attaching-and-effacing (A/E) lesion formation, while in vitro they employ diverse strategies to trigger actin polymerization. Strains belonging to the EPEC-1 lineage trigger strong actin polymerization via tyrosine phosphorylation of the type III secretion system (T3SS) effector Tir, recruitment of Nck, and activation of N-WASP. Strains belonging to EPEC-2 and EPEC-4 can trigger strong actin polymerization by dual mechanisms, since while employing the Tir-Nck pathway they can additionally activate N-WASP via the T3SS effectors TccP2 and TccP, respectively. It is currently not known if the ability to trigger actin polymerization by twin mechanisms increases in vivo virulence or fitness. Since mice are resistant to EPEC infection, in vivo studies are frequently done using the murine model pathogen Citrobacter rodentium, which shares with EPEC-1 strains the ability to induce A/E lesions and trigger strong actin polymerization via the Tir:Nck pathway. In order to model infections with EPEC-2 and EPEC-4, we constructed C. rodentium strains expressing TccP. Using a mouse intestinal in vitro organ culture model and oral gavage into C57BL/6 mice, we have shown that TccP can cooperate with Tir of C. rodentium. The recombinant strains induced typical A/E lesions ex vivo and in vivo. Expression of TccP did not alter C. rodentium colonization dynamics or pathology. In competition with the wild-type strain, expression of TccP in C. rodentium did not confer a competitive advantage.
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Hamaguchi M, Hamada D, Suzuki KN, Sakata I, Yanagihara I. Molecular basis of actin reorganization promoted by binding of enterohaemorrhagic Escherichia coli EspB to α-catenin. FEBS J 2008; 275:6260-7. [DOI: 10.1111/j.1742-4658.2008.06750.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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25
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Yuste M, Orden JA, De La Fuente R, Ruiz-Santa-Quiteria JA, Cid D, Martínez-Pulgarín S, Domínguez-Bernal G. Polymerase chain reaction typing of genes of the locus of enterocyte effacement of ruminant attaching and effacing Escherichia coil. CANADIAN JOURNAL OF VETERINARY RESEARCH = REVUE CANADIENNE DE RECHERCHE VETERINAIRE 2008; 72:444-448. [PMID: 19086378 PMCID: PMC2568050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Accepted: 12/18/2007] [Indexed: 05/27/2023]
Abstract
The variability of the tir, espA, and espD genes of the locus of enterocyte effacement (LEE) in 185 attaching and effacing Escherichia coli (AEEC) strains isolated from healthy and diarrheic cattle, sheep, and goats was investigated by polymerase chain reaction. Nineteen of the strains were enterohemorrhagic E. coli (EHEC); the other 166 were enteropathogenic E. coli (EPEC). The combinations of the tir and esp genes were associated with the variants of the eae gene but not with a strain's belonging to the EPEC or EHEC group, animal species, or health status (healthy or diarrheic) of the animal. In addition, most of the strains showed the same combinations of LEE genes and serogroups as have been found in AEEC strains isolated from humans, which indicates that ruminants seem to be an EPEC reservoir for humans.
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Affiliation(s)
| | | | | | - José A. Ruiz-Santa-Quiteria
- Address all correspondence to Dr. José A. Orden; telephone: +34 91 394 3704; fax: +34 91 394 3795; e-mail:
Drs. María Yuste and José A. Orden contributed equally to this work
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26
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Fröhlicher E, Krause G, Zweifel C, Beutin L, Stephan R. Characterization of attaching and effacing Escherichia coli (AEEC) isolated from pigs and sheep. BMC Microbiol 2008; 8:144. [PMID: 18786265 PMCID: PMC2571105 DOI: 10.1186/1471-2180-8-144] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2008] [Accepted: 09/11/2008] [Indexed: 11/13/2022] Open
Abstract
Background Attaching and effacing Escherichia coli (AEEC) are characterized by their ability to cause attaching-and-effacing (A/E) lesions in the gut mucosa of human and animal hosts leading to diarrhoea. The genetic determinants for the production of A/E lesions are located on the locus of enterocyte effacement (LEE), a pathogenicity island that also contains the genes encoding intimin (eae). This study reports data on the occurrence of eae positive E. coli carried by healthy pigs and sheep at the point of slaughter, and on serotypes, intimin variants, and further virulence factors of isolated AEEC strains. Results Faecal samples from 198 finished pigs and 279 sheep were examined at slaughter. The proportion of eae positive samples was 89% for pigs and 55% for sheep. By colony dot-blot hybridization, AEEC were isolated from 50 and 53 randomly selected porcine and ovine samples and further characterized. Strains of the serotypes O2:H40, O3:H8 and O26:H11 were found in both pigs and sheep. In pigs O2:H40, O2:H49, O108:H9, O145:H28 and in sheep O2:H40, O26:H11, O70:H40, O146:H21 were the most prevalent serotypes among typable strains. Eleven different intimin types were detected, whereas γ2/θ was the most frequent, followed by β1, ε and γ1. All but two ovine strains tested negative for the genes encoding Shiga toxins. All strains tested negative for the bfpA gene and the EAF plasmid. EAST1 (astA) was present in 18 of the isolated strains. Conclusion Our data show that pigs and sheep are a source of serologically and genetically diverse intimin-harbouring E. coli strains. Most of the strains show characteristics of atypical enteropathogenic E. coli. Nevertheless, there are stx-negative AEEC strains belonging to serotypes and intimin types that are associated with classical enterohaemorrhagic E. coli strains (O26:H11, β1; O145:H28, γ1).
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Affiliation(s)
- Erik Fröhlicher
- Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland.
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Shames SR, Auweter SD, Finlay BB. Co-evolution and exploitation of host cell signaling pathways by bacterial pathogens. Int J Biochem Cell Biol 2008; 41:380-9. [PMID: 18775503 DOI: 10.1016/j.biocel.2008.08.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Revised: 07/28/2008] [Accepted: 08/01/2008] [Indexed: 01/07/2023]
Abstract
Bacterial pathogens have evolved by combinations of gene acquisition, deletion, and modification, which increases their fitness. Additionally, bacteria are able to evolve in "quantum leaps" via the ability to promiscuously acquire new genes. Many bacterial pathogens - especially Gram-negative enteric pathogens - have evolved mechanisms by which to subvert signal transduction pathways of eukaryotic cells by expressing genes that mimic or regulate host protein factors involved in a variety of signaling cascades. This results in the ability to cause diseases ranging from tumor formation in plants to gastroenteritis and bubonic plague. Here, we present recent advances on mechanisms of bacterial pathogen evolution, including specific signaling cascades targeted by their virulence genes with an emphasis on the ubiquitin modification system, Rho GTPase regulators, cytoskeletal modulators, and host innate immunity. We also comment briefly on evolution of host defense mechanisms in place that limit disease caused by bacterial pathogens.
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Affiliation(s)
- Stephanie R Shames
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
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Prevalence and sequence diversity of a factor required for actin-based motility in natural populations of Burkholderia species. J Clin Microbiol 2008; 46:2418-22. [PMID: 18495853 PMCID: PMC2446894 DOI: 10.1128/jcm.00368-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Actin-based motility of the melioidosis pathogen Burkholderia pseudomallei requires BimA. We report a high degree of conservation of bimA in 99 B. pseudomallei isolates from the area of endemicity. A geographically restricted subset of B. pseudomallei isolates harbored a B. mallei-like bimA allele (12.1%), confounding a differential diagnostic test based on amplification of species-specific bimA regions.
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Jenkins C, Evans J, Chart H, Willshaw GA, Frankel G. Escherichia coli serogroup O26--a new look at an old adversary. J Appl Microbiol 2008; 104:14-25. [PMID: 18171379 DOI: 10.1111/j.1365-2672.2007.03465.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Escherichia coli serogroup O26 played an important part in the early work on Verocytotoxin and is an established diarrhoeal pathogen. Recently, Verocytotoxigenic E. coli (VTEC) O26 has been increasingly associated with diarrhoeal disease and frequently linked to outbreaks and cases of haemolytic uraemic syndrome (HUS). This review investigates the pathogenicity, geographical distribution, changing epidemiology, routes of transmission and improved detection of VTEC O26. Laboratory data on VTEC O26 isolates and clinical data on HUS suggest a true difference in the incidence of VTEC O26 in different geographic locations. However, few diagnostic laboratories use molecular methods to detect VTEC and so it is difficult to assess the role of VTEC O26 in causing diarrhoeal disease. VTEC O26 is frequently found in the cattle population but rarely in food. However, the small number of outbreaks analysed to date are thought to be food-borne rather than associated with direct or indirect contact with livestock or their faeces. The increase in awareness of VTEC O26 in the clinical and veterinary setting has coincided with the development of novel techniques that have improved our ability to detect and characterize this pathogen.
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Affiliation(s)
- C Jenkins
- Department of Medical Microbiology, Royal Free Hospital, NW3 2QG, London, UK.
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Iguchi A, Ooka T, Ogura Y, Asadulghani, Nakayama K, Frankel G, Hayashi T. Genomic comparison of the O-antigen biosynthesis gene clusters of Escherichia coli O55 strains belonging to three distinct lineages. MICROBIOLOGY-SGM 2008; 154:559-570. [PMID: 18227260 DOI: 10.1099/mic.0.2007/013334-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Typical enteropathogenic Escherichia coli (EPEC) O55 : H7 is regarded as the closest relative of enterohaemorrhagic E. coli (EHEC) O157 : H7. Both serotypes usually express the gamma1 intimin subclass and trigger actin polymerization by the Tir-TccP pathway. However, atypical O55 : H7 strains capable of triggering actin polymerization via the Tir-Nck pathway have recently been identified. In this study, we investigated the genotypic differences and phylogenetic relationships between typical and atypical O55 : H7 strains. We show that the atypical O55 : H7 strains, which express the theta intimin subclass and lack both tccP and tccP2, belong to an E. coli lineage distinct from the typical O55 : H7 and from the EPEC O55 : H6, which also uses the Tir-Nck actin polymerization pathway. We conducted genomic comparisons of the chromosomal regions covering the O-antigen gene cluster and its flanking regions between the three O55 lineages by RFLP analysis of PCR products and DNA sequencing analysis of about 65 kb chromosomal regions. This unexpectedly revealed that horizontal transfer of large fragments (> or =40 kb) encoding the O55-antigen gene cluster and part of the neighbouring colanic acid gene cluster was involved in the emergence of the three O55 E. coli lineages. The data provide new insights into the mechanisms involved in the generation of a wide variety of O-serotypes in Gram-negative bacteria.
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Affiliation(s)
- Atsushi Iguchi
- Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Tadasuke Ooka
- Division of Microbiology, Department of Infectious Disease, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Yoshitoshi Ogura
- Division of Microbiology, Department of Infectious Disease, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan.,Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Asadulghani
- Division of Microbiology, Department of Infectious Disease, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Keisuke Nakayama
- Division of Microbiology, Department of Infectious Disease, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Gad Frankel
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Tetsuya Hayashi
- Division of Microbiology, Department of Infectious Disease, Faculty of Medicine, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan.,Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
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31
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Frankel G, Phillips AD. Attaching effacing Escherichia coli and paradigms of Tir-triggered actin polymerization: getting off the pedestal. Cell Microbiol 2007; 10:549-56. [PMID: 18053003 DOI: 10.1111/j.1462-5822.2007.01103.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) colonize the gut mucosa via attaching and effacing (A/E) lesions. For years cultured cells were used as model systems to study A/E lesion formation, which showed actin accumulation under attached bacteria that can be raised above the plasma membrane in a pedestal-shaped structure. Studies of prototypical strains revealed that although both converge on N-WASP EPEC and EHEC O157:H7 use different actin polymerization pathways. While EPEC use the Tir-Nck pathway, Tir(EHECO157) cooperates with TccP/EspF(U) to activate N-WASP. However, recent in vitro studies revealed a common EPEC and EHEC Tir-dependent and Nck-independent inefficient actin polymerization pathway. Unexpectedly, bacterial populations studies demonstrated that most non-O157 EHEC strains and EPEC lineage 2 strains can utilize both the Nck and TccP2 pathways in vitro. Importantly, in vivo and ex vivo mucosal infections have shown efficient A/E lesion formation independently of Nck and TccP. This review covers the progression in our understanding of EPEC and EHEC infection, through the different milestones obtained using cultured cells, to the realization that EPEC and EHEC have much more in common than previously appreciated and that mucosal attachment and microvillous effacement may be the key events, rather than pedestal formation.
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Affiliation(s)
- Gad Frankel
- Division of Cell and Molecular Biology, Imperial College London, London, UK.
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32
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Whale AD, Hernandes RT, Ooka T, Beutin L, Schüller S, Garmendia J, Crowther L, Vieira MAM, Ogura Y, Krause G, Phillips AD, Gomes TAT, Hayashi T, Frankel G. TccP2-mediated subversion of actin dynamics by EPEC 2 - a distinct evolutionary lineage of enteropathogenic Escherichia coli. MICROBIOLOGY-SGM 2007; 153:1743-1755. [PMID: 17526832 PMCID: PMC2884950 DOI: 10.1099/mic.0.2006/004325-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhoea in developing countries. While colonizing the gut mucosa, EPEC triggers extensive actin-polymerization activity at the site of intimate bacterial attachment, which is mediated by avid interaction between the outer-membrane adhesin intimin and the type III secretion system (T3SS) effector Tir. The prevailing dogma is that actin polymerization by EPEC is achieved following tyrosine phosphorylation of Tir, recruitment of Nck and activation of neuronal Wiskott-Aldrich syndrome protein (N-WASP). In closely related enterohaemorrhagic E. coli (EHEC) O157 : H7, actin polymerization is triggered following recruitment of the T3SS effector TccP/EspF(U) (instead of Nck) and local activation of N-WASP. In addition to tccP, typical EHEC O157 : H7 harbour a pseudogene (tccP2). However, it has recently been found that atypical, sorbitol-fermenting EHEC O157 carries functional tccP and tccP2 alleles. Interestingly, intact tccP2 has been identified in the incomplete genome sequence of the prototype EPEC strain B171 (serotype O111 : H-), but it is missing from another prototype EPEC strain E2348/69 (O127 : H7). E2348/69 and B171 belong to two distinct evolutionary lineages of EPEC, termed EPEC 1 and EPEC 2, respectively. Here, it is reported that while both EPEC 1 and EPEC 2 triggered actin polymerization via the Nck pathway, tccP2 was found in 26 of 27 (96.2 %) strains belonging to EPEC 2, and in none of the 34 strains belonging to EPEC 1. It was shown that TccP2 was: (i) translocated by the locus of enterocyte effacement-encoded T3SS; (ii) localized at the tip of the EPEC 2-induced actin-rich pedestals in infected HeLa cells and human intestinal in vitro organ cultures ex vivo; and (iii) essential for actin polymerization in infected Nck-/- cells. Therefore, unlike strains belonging to EPEC 1, strains belonging to EPEC 2 can trigger actin polymerization using both Nck and TccP2 actin-polymerization signalling cascades.
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Affiliation(s)
- Andrew D. Whale
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Rodrigo T. Hernandes
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tadasuke Ooka
- Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Lothar Beutin
- Nationales Referenzlabor für Escherichia coli, Bundesinstitut für Risikobewertung, Diedersdorfer Weg 1, D-12277 Berlin, Germany
| | - Stephanie Schüller
- Centre for Paediatric Gastroenterology, Royal Free and University College Medical School, London, UK
| | - Junkal Garmendia
- Fundación Caubet-Cimera, Recinto Hospital Joan March, Carretera Soller Km 1207110 Bunyola, Mallorca, Spain
| | - Lynette Crowther
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
| | - Mônica A. M. Vieira
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Yoshitoshi Ogura
- Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Gladys Krause
- Nationales Referenzlabor für Escherichia coli, Bundesinstitut für Risikobewertung, Diedersdorfer Weg 1, D-12277 Berlin, Germany
| | - Alan D. Phillips
- Centre for Paediatric Gastroenterology, Royal Free and University College Medical School, London, UK
| | - Tania A. T. Gomes
- Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Tetsuya Hayashi
- Division of Bioenvironmental Science, Frontier Science Research Center, University of Miyazaki, 5200 Kiyotake, Miyazaki 889-1692, Japan
| | - Gad Frankel
- Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
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Enteropathogenic Escherichia coli O125:H6 triggers attaching and effacing lesions on human intestinal biopsy specimens independently of Nck and TccP/TccP2. Infect Immun 2007; 76:361-8. [PMID: 17984209 PMCID: PMC2223649 DOI: 10.1128/iai.01199-07] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Typical enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) employ either Nck, TccP/TccP2, or Nck and TccP/TccP2 pathways to activate the neuronal Wiskott-Aldrich syndrome protein (N-WASP) and to trigger actin polymerization in cultured cells. This phenotype is used as a marker for the pathogenic potential of EPEC and EHEC strains. In this paper we report that EPEC O125:H6, which represents a large category of strains, lacks the ability to utilize either Nck or TccP/TccP2 and hence triggers actin polymerization in vitro only inefficiently. However, we show that infection of human intestinal biopsies with EPEC O125:H6 results in formation of typical attaching and effacing lesions. Expression of TccP in EPEC O125:H6, which harbors an EHEC O157-like Tir, resulted in efficient actin polymerization in vitro and enhanced colonization of human intestinal in vitro organ cultures with detectable N-WASP and electron-dense material at the site of bacterial adhesion. These results show the existence of a natural category of EPEC that colonizes the gut mucosa using Nck- and TccP-independent mechanisms. Importantly, the results highlight yet again the fact that conclusions made on the basis of in vitro cell culture models cannot be extrapolated wholesale to infection of mucosal surfaces and that the ability to induce actin polymerization on cultured cells should not be used as a definitive marker for EPEC and EHEC virulence.
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Extensive genomic diversity and selective conservation of virulence-determinants in enterohemorrhagic Escherichia coli strains of O157 and non-O157 serotypes. Genome Biol 2007; 8:R138. [PMID: 17711596 PMCID: PMC2323221 DOI: 10.1186/gb-2007-8-7-r138] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 06/06/2007] [Accepted: 07/10/2007] [Indexed: 01/27/2023] Open
Abstract
BACKGROUND Enterohemorrhagic Escherichia coli (EHEC) O157 causes severe food-borne illness in humans. The chromosome of O157 consists of 4.1 Mb backbone sequences shared by benign E. coli K-12, and 1.4 Mb O157-specific sequences encoding many virulence determinants, such as Shiga toxin genes (stx genes) and the locus of enterocyte effacement (LEE). Non-O157 EHECs belonging to distinct clonal lineages from O157 also cause similar illness in humans. According to the 'parallel' evolution model, they have independently acquired the major virulence determinants, the stx genes and LEE. However, the genomic differences between O157 and non-O157 EHECs have not yet been systematically analyzed. RESULTS Using microarray and whole genome PCR scanning analyses, we performed a whole genome comparison of 20 EHEC strains of O26, O111, and O103 serotypes with O157. In non-O157 EHEC strains, although genome sizes were similar with or rather larger than O157 and the backbone regions were well conserved, O157-specific regions were very poorly conserved. Around only 20% of the O157-specific genes were fully conserved in each non-O157 serotype. However, the non-O157 EHECs contained a significant number of virulence genes that are found on prophages and plasmids in O157, and also multiple prophages similar to, but significantly divergent from, those in O157. CONCLUSION Although O157 and non-O157 EHECs have independently acquired a huge amount of serotype- or strain-specific genes by lateral gene transfer, they share an unexpectedly large number of virulence genes. Independent infections of similar but distinct bacteriophages carrying these virulence determinants are deeply involved in the evolution of O157 and non-O157 EHECs.
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Kozub-Witkowski E, Krause G, Frankel G, Kramer D, Appel B, Beutin L. Serotypes and virutypes of enteropathogenic and enterohaemorrhagic Escherichia coli strains from stool samples of children with diarrhoea in Germany. J Appl Microbiol 2007; 104:403-10. [PMID: 17887989 DOI: 10.1111/j.1365-2672.2007.03545.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS To investigate the prevalence of traditional and emerging types of enteropathogenic (EPEC) and enterohaemorrhagic Escherichia coli (EHEC) strains in stool samples from children with diarrhoea and to characterize their virulence genes involved in the attaching and effacing (A/E) phenotype. METHODS AND RESULTS Serological and PCR-based methods were used for detection and isolation of EPEC and EHEC strains from 861 stool samples from diarrhoeic children. Agglutination with traditional EPEC and EHEC O-group-specific antisera resulted in detection of 38 strains; 26 of these carried virulence factors of EPEC or EHEC. PCR screening for the eae gene resulted in isolation of 97 strains, five carried genes encoding Shiga toxins (stx), one carried the bfpA gene and 91 were atypical EPEC. The 97 EPEC and EHEC strains were divided into 36 O-serogroups and 21 H-types, only nine strains belonged to the traditional EPEC O-groups O26, O55, O86 and O128. In contrast, EPEC serotypes O28:H28, O51:H49, O115:H38 and O127:H40 were found in multiple cases. Subtyping the virulence factors intimin, Tir and Tir-cytoskeleton coupling effector protein (TccP)/TccP2 resulted in further classification of 93.8% of the 97 strains. CONCLUSIONS Our findings show a clear advantage of the eae-PCR over the serological detection method for identification of EPEC and EHEC strains from human patients. SIGNIFICANCE AND IMPACT OF THE STUDY Molecular detection by the eae-PCR followed by serotyping and virutyping is useful for monitoring trends in EPEC and EHEC infections and to discover their possible reservoirs.
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Affiliation(s)
- E Kozub-Witkowski
- LADR GmbH, Medizinisches Versorgungszentrum, Dr. Kramer & Kollegen, Geesthacht, Germany
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Brady MJ, Campellone KG, Ghildiyal M, Leong JM. Enterohaemorrhagic and enteropathogenicEscherichia coliTir proteins trigger a common Nck-independent actin assembly pathway. Cell Microbiol 2007; 9:2242-53. [PMID: 17521329 DOI: 10.1111/j.1462-5822.2007.00954.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The Tir proteins of enterohaemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC respectively) are each translocated into the host plasma membrane where they promote F-actin pedestals in epithelial cells beneath adherent bacteria, but the two proteins act by different means. The canonical EPEC Tir becomes phosphorylated on tyrosine residue 474 (Y474) to recruit the host adaptor protein Nck, and also stimulates an inefficient, Nck-independent pathway utilizing tyrosine residue 454 (Y454). In contrast, the canonical EHEC Tir lacks Y474 and instead utilizes residues 452-463 to recruit EspF(U), an EHEC-specific effector that stimulates robust Nck-independent actin assembly. EHEC Tir Y458 and EPEC Tir Y454 are both part of an asparagine-proline-tyrosine (NPY) sequence. We report that each of the EHEC Tir NPY residues is required for EspF(U) recruitment and pedestal formation, and each of the EPEC Tir NPY residues is critical for inefficient, Nck-independent pedestal formation. Introduction of EspF(U) into EPEC dramatically enhanced Nck-independent actin assembly by EPEC Tir in a manner dependent on NPY(454). These results suggest that EPEC and EHEC Tir trigger a common Nck-independent actin assembly pathway and are both derived from an ancestral Tir molecule that utilized NPY to stimulate low-level pedestal formation.
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Affiliation(s)
- Michael J Brady
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
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