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Gonyar LA, Sauder AB, Mortensen L, Willsey GG, Kendall MM. The yad and yeh fimbrial loci influence gene expression and virulence in enterohemorrhagic Escherichia coli O157:H7. mSphere 2024:e0012424. [PMID: 38904402 DOI: 10.1128/msphere.00124-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Accepted: 05/15/2024] [Indexed: 06/22/2024] Open
Abstract
Fimbriae are essential virulence factors for many bacterial pathogens. Fimbriae are extracellular structures that attach bacteria to surfaces. Thus, fimbriae mediate a critical step required for any pathogen to establish infection by anchoring a bacterium to host tissue. The human pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7encodes 16 fimbriae that may be important for EHEC to initiate infection and allow for productive expression of virulence traits important in later stages of infection, including a type III secretion system (T3SS) and Shiga toxin; however, the roles of most EHEC fimbriae are largely uncharacterized. Here, we provide evidence that two EHEC fimbriae, Yad and Yeh, modulate expression of diverse genes including genes encoding T3SS and Shiga toxin and that these fimbriae are required for robust colonization of the gastrointestinal tract. These findings reveal a significant and previously unappreciated role for fimbriae in bacterial pathogenesis as important determinants of virulence gene expression.IMPORTANCEFimbriae are extracellular proteinaceous structures whose defining role is to anchor bacteria to surfaces. This is a fundamental step for bacterial pathogens to establish infection in a host. Here, we show that the contributions of fimbriae to pathogenesis are more complex. Specifically, we demonstrate that fimbriae influence expression of virulence traits essential for disease progression in the intestinal pathogen enterohemorrhagic Escherichia coli. Gram-positive and Gram-negative bacteria express multiple fimbriae; therefore, these findings may have broad implications for understanding how pathogens use fimbriae, beyond adhesion, to initiate infection and coordinate gene expression, which ultimately results in disease.
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Affiliation(s)
- Laura A Gonyar
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Amber B Sauder
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Lindsay Mortensen
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Graham G Willsey
- Department of Microbiology and Molecular Genetics, Larner College of Medicine, University of Vermont, Burlington, Vermont, USA
| | - Melissa M Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
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2
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Muche S, El-Fenej J, Mihaita A, Mrozek Z, Cleary S, Critelli B, Marino M, Yu W, Amos B, Hunter T, Riga M, Buerkert T, Bhatt S. The two sRNAs OmrA and OmrB indirectly repress transcription from the LEE1 promoter of enteropathogenic Escherichia coli. Folia Microbiol (Praha) 2023; 68:415-430. [PMID: 36547806 DOI: 10.1007/s12223-022-01025-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 11/26/2022] [Indexed: 12/24/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) is a diarrheagenic bacterium that predominantly infects infants in developing countries. EPEC forms attaching and effacing (A/E) lesions on the apical surface of the small intestine, leading to diarrhea. The locus of enterocyte effacement (LEE) is both necessary and sufficient for A/E lesion morphogenesis by EPEC. Gene expression from this virulence determinant is controlled by an elaborate regulatory web that extends beyond protein-based transcriptional regulators and includes small regulatory RNA (sRNA) that exert their effects posttranscriptionally. To date, only 4 Hfq-dependent sRNAs-MgrR, RyhB, McaS, and Spot42-have been identified that affect the LEE of EPEC by diverse mechanisms and elicit varying regulatory outcomes. In this study, we demonstrate that the paralogous Hfq-dependent sRNAs OmrA and OmrB globally silence the LEE to diminish the ability of EPEC to form A/E lesions. Interestingly, OmrA and OmrB do not appear to directly target a LEE-encoded gene; rather, they repress transcription from the LEE1 promoter indirectly, by means of an as-yet-unidentified transcriptional factor that binds within 200 base pairs upstream of the transcription start site to reduce the expression of the LEE master regulator Ler, which, in turn, leads to reduced morphogenesis of A/E lesions. Additionally, OmrA and OmrB also repress motility in EPEC by targeting the 5' UTR of the flagellar master regulator, flhD.
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Affiliation(s)
- Sarah Muche
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Jihad El-Fenej
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
- Center for Immunity and Inflammation and Department of Pathology, New Jersey Medical School, Rutgers-The State University of New Jersey, Newark, NJ, USA
| | - Alexa Mihaita
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Zoe Mrozek
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Sean Cleary
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
- Philadelphia College of Osteopathic Medicine, 4170 City Avenue, Philadelphia, PA, 19131, USA
| | - Brian Critelli
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Mary Marino
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Wenlan Yu
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Brianna Amos
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Tressa Hunter
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Michael Riga
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Thomas Buerkert
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA
| | - Shantanu Bhatt
- Department of Biology, Saint Joseph's University, 5600 City Avenue, SC124, Philadelphia, PA, 19131, USA.
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3
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Genomic Island-Encoded Histidine Kinase and Response Regulator Coordinate Mannose Utilization with Virulence in Enterohemorrhagic Escherichia coli. mBio 2023; 14:e0315222. [PMID: 36786613 PMCID: PMC10128022 DOI: 10.1128/mbio.03152-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a highly adaptive pathogen and has acquired diverse genetic elements, such as genomic islands and prophages, via horizontal gene transfer to promote fitness in vivo. Two-component signaling systems (TCSs) allow bacteria to sense, respond to, and adapt to various environments. This study identified a putative two-component signaling system composed of the histidine kinase EDL5436 (renamed LmvK) and the response regulator EDL5428 (renamed LmvR) in EHEC. lmvK and lmvR along with EDL5429 to EDL5434 (EDL5429-5434) between them constitute the OI167 genomic island and are highly associated with the EHEC pathotype. EDL5429-5434 encode transporters and metabolic enzymes that contribute to growth on mannose and are directly upregulated by LmvK/LmvR in the presence of mannose, as revealed by quantitative PCR (qPCR) and DNase I footprint assays. Moreover, LmvR directly activates the expression of the type III secretion system in response to mannose and promotes the formation of attaching and effacing lesions on HeLa cells. Using human colonoid and mouse infection models, we show that lmvK and lmvR contributed greatly to adherence and microcolony (MC) formation ex vivo and colonization in vivo. Finally, RNA sequencing and chromatin immunoprecipitation coupled with sequencing analyses identified additional direct targets of LmvR, most of which are involved in metabolism. Given that mannose is a mucus-derived sugar that induces virulence and is preferentially used by EHEC during infection, our data revealed a previously unknown mechanism by which EHEC recognizes the host metabolic landscape and regulates virulence expression accordingly. Our findings provide insights into how pathogenic bacteria evolve by acquiring genetic elements horizontally to adapt to host environments. IMPORTANCE The gastrointestinal tract represents a complex and challenging environment for enterohemorrhagic Escherichia coli (EHEC). However, EHEC is a highly adaptable pathogen, requiring only 10 to 100 CFUs to cause infection. This ability was achieved partially by acquiring mobile genetic elements, such as genomic islands, that promote overall fitness. Mannose is an intestinal mucus-derived sugar that stimulates virulence and is preferentially used by EHEC during infection. Here, we characterize the OI167 genomic island of EHEC, which encodes a novel two-component signaling system (TCS) and transporters and metabolic enzymes (EDL5429-5434) involved in mannose utilization. The TCS directly upregulates EDL5429-5434 and genes encoding the type III secretion system in the presence of mannose. Moreover, the TCS contributes greatly to EHEC virulence ex vivo and in vivo. Our data demonstrate an elegant example in which EHEC strains evolve by acquiring genetic elements horizontally to recognize the host metabolic landscape and regulate virulence expression accordingly, leading to successful infections.
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Jia T, Wu P, Liu B, Liu M, Mu H, Liu D, Huang M, Li L, Wei Y, Wang L, Yang Q, Liu Y, Yang B, Huang D, Yang L, Liu B. The phosphate-induced small RNA EsrL promotes E. coli virulence, biofilm formation, and intestinal colonization. Sci Signal 2023; 16:eabm0488. [PMID: 36626577 DOI: 10.1126/scisignal.abm0488] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Escherichia coli are part of the normal intestinal microbiome, but some enterohemorrhagic E. coli (EHEC) and enteropathogenic E. coli (EPEC) strains can cause potentially life-threatening gastroenteritis. Virulence factors underlying the ability of EHEC and EPEC to cause disease include those encoded in the locus of the enterocyte effacement (LEE) pathogenicity island. Here, we demonstrated that EsrL, a small RNA present in many E. coli strains, promoted pathogenicity, adhesion, and biofilm formation in EHEC and EPEC. PhoB, the response regulator of the two-component system that controls cellular responses to phosphate, directly repressed esrL expression under low-phosphate conditions. A phosphate-rich environment, similar to that of the human intestine, relieved PhoB-mediated repression of esrL. EsrL interacted with and stabilized the LEE-encoded regulator (ler) transcript, which encodes a transcription factor for LEE genes, leading to increased bacterial adhesion to cultured cells and colonization of the rabbit colon. EsrL also bound to and stabilized the fimC transcript, which encodes a chaperone that is required for the assembly of type 1 pili, resulting in enhanced cell adhesion in pathogenic E. coli and enhanced biofilm formation in pathogenic and nonpathogenic E. coli. Our findings demonstrate that EsrL stimulates the expression of virulence genes in both EHEC and EPEC under phosphate-rich conditions, thus promoting the pathogenicity of EHEC and EPEC in the nutrient-rich gut environment.
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Affiliation(s)
- Tianyuan Jia
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Pan Wu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Bin Liu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,Center for Microbial Functional Genomics and Detection Technology, Ministry of Education, Tianjin, China
| | - Miaomiao Liu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Huiqian Mu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Dan Liu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Min Huang
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Linxing Li
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Yi Wei
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Lu Wang
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Qian Yang
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China
| | - Yutao Liu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,Center for Microbial Functional Genomics and Detection Technology, Ministry of Education, Tianjin, China
| | - Bin Yang
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,Center for Microbial Functional Genomics and Detection Technology, Ministry of Education, Tianjin, China
| | - Di Huang
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,Center for Microbial Functional Genomics and Detection Technology, Ministry of Education, Tianjin, China.,Nankai International Advanced Research Institute, Shenzhen, China
| | - Liang Yang
- School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Bin Liu
- Institute of Translational Medicine Research, Tianjin Union Medical Center, TEDA Institute of Biological Sciences and Biotechnology, Nankai University, Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Nankai University, Ministry of Education, Tianjin, China.,Center for Microbial Functional Genomics and Detection Technology, Ministry of Education, Tianjin, China.,Nankai International Advanced Research Institute, Shenzhen, China
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5
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Lu X, Wu D, Zhao X, Zhang M, Ren K, Zhou N, Zhao Y, Qian W. Effect of ethanolamine utilization on the pathogenicity and metabolic profile of enterotoxigenic Escherichia coli. Appl Microbiol Biotechnol 2022; 106:8195-8210. [PMID: 36370159 DOI: 10.1007/s00253-022-12261-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 10/21/2022] [Accepted: 10/25/2022] [Indexed: 11/15/2022]
Abstract
Bacterial pathogenicity is greatly affected by nutrient recognition and utilization in the host microenvironment. The characterization of enteral nutrients that promote intestinal pathogen virulence is helpful for developing new adjuvant therapies and inhibiting host damage. Ethanolamine (EA), as a major component of intestinal epithelial cells and bacterial membranes, is abundant in the intestine. Here, we provide the first demonstration that the critical human and porcine pathogen enterotoxigenic Escherichia coli (ETEC) can utilize EA as a nitrogen source, which affects its virulence phenotype. We found that compared with that in M9 medium (containing NH4Cl), EA inhibited ETEC growth to a certain extent; however, the relative expression levels of virulence-related genes, such as ltA (3.0-fold), fimH (2.9-fold), CfaD (2.6-fold), gspD (3.6-fold), and qesE (1.3-fold), increased significantly with 15 mM EA as a nitrogen source (P < 0.05), and the adhesion efficiency of ETEC to Caco-2 cells increased approximately 4.2-fold. In Caco-2 cells, the relative cell viability decreased from 74.8 to 63.4%, and the transepithelial electrical resistance (TEER) cells decreased to 74.8% with intestinal EA (4 mM). In addition, the relative expression levels of proinflammatory factors, such as TNF-α (3.2-fold), INF-γ (2.9-fold), and IL-1β (1.98-fold), in ETEC-infected Caco-2 cells were significantly upregulated (P < 0.05) under EA exposure; however, the above virulence changes were not found in ΔeutR and ΔeutB ETEC. A gas chromatography-mass spectrometry (GC-MS)-based untargeted metabolomics approach was then employed to reveal EA-induced metabolic reprogramming related to ETEC virulence. The data showed that most metabolites related to carbohydrate, aspartate and glutamate metabolism, shikimic acid metabolism, and serine metabolism in ETEC exhibited a decreasing trend with increases in the EA concentration from 0 to 15 mM, but the branched-chain amino acid (BCAA) levels in ETEC increased in a dose-dependent manner under EA exposure. Our data suggest that the intestinal EA concentration can significantly affect the virulence phenotype, metabolic profile, and pathogenicity of ETEC. KEY POINTS: • ETEC growth and virulence gene expression could be regulated by ethanolamine. • The intestinal concentration of EA promoted the damaging effect of ETEC on the host epithelial barrier. • The promoting effect of EA on ETEC toxicity may be related to BCAA metabolism.
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Affiliation(s)
- Xi Lu
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Dingyan Wu
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Xin Zhao
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Mingxin Zhang
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Ke Ren
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Ningning Zhou
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China
| | - Yanni Zhao
- School of Food Science and Engineering, Shaanxi University of Science and Technology, Xi'an, Shaanxi, 710021, China.
| | - Weisheng Qian
- Tangdu Hospital, Air Force Military Medical University, Xi'an, Shaanxi, 710048, China.
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Sun H, Wang M, Liu Y, Wu P, Yao T, Yang W, Yang Q, Yan J, Yang B. Regulation of flagellar motility and biosynthesis in enterohemorrhagic Escherichia coli O157:H7. Gut Microbes 2022; 14:2110822. [PMID: 35971812 PMCID: PMC9387321 DOI: 10.1080/19490976.2022.2110822] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
ABSTARCTEnterohemorrhagic Escherichia coli (EHEC) O157:H7 is a human pathogen that causes a variety of diseases, such as hemorrhagic colitis and lethal hemolytic uremic syndrome. Flagellum-dependent motility plays diverse roles in the pathogenesis of EHEC O157:H7, including its migration to an optimal host site, adherence and colonization, survival at the infection site, and post-infection dispersal. However, it is very expensive for cellular economy in terms of the number of genes and the energy required for flagellar biosynthesis and functioning. Furthermore, the flagellar filament bears strong antigenic properties that induce a strong host immune response. Consequently, the flagellar gene expression and biosynthesis are highly regulated to occur at the appropriate time and place by different regulatory influences. The present review focuses on the regulatory mechanisms of EHEC O157:H7 motility and flagellar biosynthesis, especially in terms of flagellar gene regulation by environmental factors, regulatory proteins, and small regulatory RNAs.
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Affiliation(s)
- Hongmin Sun
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Min Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Yutao Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Pan Wu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Ting Yao
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Wen Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Qian Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Jun Yan
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China
| | - Bin Yang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin, China,CONTACT Bin Yang TEDA Institute of Biological Sciences and Biotechnology, Nankai University, TEDA, Tianjin300457, P. R. China
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7
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Escherichia coli 0157:H7 virulence factors and the ruminant reservoir. Curr Opin Infect Dis 2022; 35:205-214. [PMID: 35665714 PMCID: PMC9302714 DOI: 10.1097/qco.0000000000000834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW This review updates recent findings about Escherichia coli O157:H7 virulence factors and its bovine reservoir. This Shiga toxin (Stx)-producing E. coli belongs to the Enterohemorrhagic E. coli (EHEC) pathotype causing hemorrhagic colitis. Its low infectious dose makes it an efficient, severe, foodborne pathogen. Although EHEC remains in the intestine, Stx can translocate systemically and is cytotoxic to microvascular endothelial cells, especially in the kidney and brain. Disease can progress to life-threatening hemolytic uremic syndrome (HUS) with hemolytic anemia, acute kidney failure, and thrombocytopenia. Young children, the immunocompromised, and the elderly are at the highest risk for HUS. Healthy ruminants are the major reservoir of EHEC and cattle are the primary source of human exposure. RECENT FINDINGS Advances in understanding E. coli O157:H7 pathogenesis include molecular mechanisms of virulence, bacterial adherence, type three secretion effectors, intestinal microbiome, inflammation, and reservoir maintenance. SUMMARY Many aspects of E. coli O157:H7 disease remain unclear and include the role of the human and bovine intestinal microbiomes in infection. Therapeutic strategies involve controlling inflammatory responses and/or intestinal barrier function. Finally, elimination/reduction of E. coli O157:H7 in cattle using CRISPR-engineered conjugative bacterial plasmids and/or on-farm management likely hold solutions to reduce infections and increase food safety/security.
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