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Pakbin B, Brück WM, Brück TB. Molecular Mechanisms of Shigella Pathogenesis; Recent Advances. Int J Mol Sci 2023; 24:2448. [PMID: 36768771 PMCID: PMC9917014 DOI: 10.3390/ijms24032448] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/21/2023] [Accepted: 01/23/2023] [Indexed: 01/28/2023] Open
Abstract
Shigella species are the main cause of bacillary diarrhoea or shigellosis in humans. These organisms are the inhabitants of the human intestinal tract; however, they are one of the main concerns in public health in both developed and developing countries. In this study, we reviewed and summarised the previous studies and recent advances in molecular mechanisms of pathogenesis of Shigella Dysenteriae and non-Dysenteriae species. Regarding the molecular mechanisms of pathogenesis and the presence of virulence factor encoding genes in Shigella strains, species of this bacteria are categorised into Dysenteriae and non-Dysenteriae clinical groups. Shigella species uses attachment, invasion, intracellular motility, toxin secretion and host cell interruption mechanisms, causing mild diarrhoea, haemorrhagic colitis and haemolytic uremic syndrome diseases in humans through the expression of effector delivery systems, protein effectors, toxins, host cell immune system evasion and iron uptake genes. The investigation of these genes and molecular mechanisms can help us to develop and design new methods to detect and differentiate these organisms in food and clinical samples and determine appropriate strategies to prevent and treat the intestinal and extraintestinal infections caused by these enteric pathogens.
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Affiliation(s)
- Babak Pakbin
- Werner Siemens Chair of Synthetic Biotechnology, Department of Chemistry, Technical University of Munich (TUM), Lichtenberg Str. 4, 85748 Garching bei München, Germany
- Institute for Life Technologies, University of Applied Sciences Western Switzerland Valais-Wallis, 1950 Sion, Switzerland
| | - Wolfram Manuel Brück
- Institute for Life Technologies, University of Applied Sciences Western Switzerland Valais-Wallis, 1950 Sion, Switzerland
| | - Thomas B. Brück
- Werner Siemens Chair of Synthetic Biotechnology, Department of Chemistry, Technical University of Munich (TUM), Lichtenberg Str. 4, 85748 Garching bei München, Germany
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2
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Abstract
The major function of the mammalian immune system is to prevent and control infections caused by enteropathogens that collectively have altered human destiny. In fact, as the gastrointestinal tissues are the major interface of mammals with the environment, up to 70% of the human immune system is dedicated to patrolling them The defenses are multi-tiered and include the endogenous microflora that mediate colonization resistance as well as physical barriers intended to compartmentalize infections. The gastrointestinal tract and associated lymphoid tissue are also protected by sophisticated interleaved arrays of active innate and adaptive immune defenses. Remarkably, some bacterial enteropathogens have acquired an arsenal of virulence factors with which they neutralize all these formidable barriers to infection, causing disease ranging from mild self-limiting gastroenteritis to in some cases devastating human disease.
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Affiliation(s)
- Micah J. Worley
- Department of Biology, University of Louisville, Louisville, Kentucky, USA,CONTACT Micah J. Worley Department of Biology, University of Louisville, 139 Life Sciences Bldg, Louisville, Kentucky, USA
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3
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Gupta A, Malwe AS, Srivastava GN, Thoudam P, Hibare K, Sharma VK. MP4: a machine learning based classification tool for prediction and functional annotation of pathogenic proteins from metagenomic and genomic datasets. BMC Bioinformatics 2022; 23:507. [PMID: 36443666 PMCID: PMC9703692 DOI: 10.1186/s12859-022-05061-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Accepted: 11/16/2022] [Indexed: 11/29/2022] Open
Abstract
Bacteria can exceptionally evolve and develop pathogenic features making it crucial to determine novel pathogenic proteins for specific therapeutic interventions. Therefore, we have developed a machine-learning tool that predicts and functionally classifies pathogenic proteins into their respective pathogenic classes. Through construction of pathogenic proteins database and optimization of ML algorithms, Support Vector Machine was selected for the model construction. The developed SVM classifier yielded an accuracy of 81.72% on the blind-dataset and classified the proteins into three classes: Non-pathogenic proteins (Class-1), Antibiotic Resistance Proteins and Toxins (Class-2), and Secretory System Associated and capsular proteins (Class-3). The classifier provided an accuracy of 79% on real dataset-1, and 72% on real dataset-2. Based on the probability of prediction, users can estimate the pathogenicity and annotation of proteins under scrutiny. Tool will provide accurate prediction of pathogenic proteins in genomic and metagenomic datasets providing leads for experimental validations. Tool is available at: http://metagenomics.iiserb.ac.in/mp4 .
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Affiliation(s)
- Ankit Gupta
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
| | - Aditya S. Malwe
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
| | - Gopal N. Srivastava
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
| | - Parikshit Thoudam
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
| | - Keshav Hibare
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
| | - Vineet K. Sharma
- grid.462376.20000 0004 1763 8131MetaBioSys Group, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal, Madhya Pradesh India
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Bueris V, Sellera FP, Fuga B, Sano E, Carvalho MPN, Couto SCF, Moura Q, Lincopan N. Convergence of virulence and resistance in international clones of WHO critical priority enterobacterales isolated from Marine Bivalves. Sci Rep 2022; 12:5707. [PMID: 35383231 PMCID: PMC8983722 DOI: 10.1038/s41598-022-09598-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 03/24/2022] [Indexed: 11/09/2022] Open
Abstract
The global spread of critical-priority antimicrobial-resistant Enterobacterales by food is a public health problem. Wild-caught seafood are broadly consumed worldwide, but exposure to land-based pollution can favor their contamination by clinically relevant antimicrobial-resistant bacteria. As part of the Grand Challenges Explorations: New Approaches to Characterize the Global Burden of Antimicrobial Resistance Program, we performed genomic surveillance and cell culture-based virulence investigation of WHO critical priority Enterobacterales isolated from marine bivalves collected in the Atlantic Coast of South America. Broad-spectrum cephalosporin-resistant Klebsiella pneumoniae and Escherichia coli isolates were recovered from eight distinct geographical locations. These strains harbored blaCTX-M-type or blaCMY-type genes. Most of the surveyed genomes confirmed the convergence of wide virulome and resistome (i.e., antimicrobials, heavy metals, biocides, and pesticides resistance). We identified strains belonging to the international high-risk clones K. pneumoniae ST307 and E. coli ST131 carrying important virulence genes, whereas in vitro experiments confirmed the high virulence potential of these strains. Thermolabile and thermostable toxins were identified in some strains, and all of them were biofilm producers. These data point to an alarming presence of resistance and virulence genes in marine environments, which may favor horizontal gene transfer and the spread of these traits to other bacterial species.
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Affiliation(s)
- Vanessa Bueris
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil. .,Laboratory of Genetics, Butantan Institute, São Paulo, Brazil.
| | - Fábio P Sellera
- Department of Internal Medicine, School of Veterinary Medicine and Animal Science, University of São Paulo, São Paulo, Brazil.,School of Veterinary Medicine, Metropolitan University of Santos, Santos, Brazil.,One Health Brazilian Resistance Project (OneBR), São Paulo, Brazil
| | - Bruna Fuga
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,One Health Brazilian Resistance Project (OneBR), São Paulo, Brazil.,Department of Clinical Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
| | - Elder Sano
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,One Health Brazilian Resistance Project (OneBR), São Paulo, Brazil
| | - Marcelo P N Carvalho
- Department of Veterinary Clinic and Surgery, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil
| | | | - Quézia Moura
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Nilton Lincopan
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.,One Health Brazilian Resistance Project (OneBR), São Paulo, Brazil.,Department of Clinical Analysis, Faculty of Pharmaceutical Sciences, University of São Paulo, São Paulo, Brazil
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5
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Zhu Z, Wang W, Cao M, Zhu Q, Ma T, Zhang Y, Liu G, Zhou X, Li B, Shi Y, Zhang J. Virulence factors and molecular characteristics of Shigella flexneri isolated from calves with diarrhea. BMC Microbiol 2021; 21:214. [PMID: 34271864 PMCID: PMC8285881 DOI: 10.1186/s12866-021-02277-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 06/28/2021] [Indexed: 11/10/2022] Open
Abstract
Background The natural hosts of Shigella are typically humans and other primates, but it has been shown that the host range of Shigella has expanded to many animals. Although Shigella is becoming a major threat to animals, there is limited information on the genetic background of local strains. The purpose of this study was to assess the presence of virulence factors and the molecular characteristics of S. flexneri isolated from calves with diarrhea. Results Fifty-four S. flexneri isolates from Gansun, Shanxi, Qinghai, Xinjiang and Tibet obtained during 2014 to 2016 possessed four typical biochemical characteristics of Shigella. The prevalences of ipaH, virA, ipaBCD, ial, sen, set1A, set1B and stx were 100 %, 100 %, 77.78 %, 79.63 %, 48.15 %, 48.15 and 0 %, respectively. Multilocus variable number tandem repeat analysis (MLVA) based on 8 variable number of tandem repeat (VNTR) loci discriminated the isolates into 39 different MLVA types (MTs), pulsed field gel electrophoresis (PFGE) based on NotI digestion divided the 54 isolates into 31 PFGE types (PTs), and multilocus sequence typing (MLST) based on 15 housekeeping genes differentiated the isolates into 7 MLST sequence types (STs). Conclusions The findings from this study enrich our knowledge of the molecular characteristics of S. flexneri collected from calves with diarrhea, which will be important for addressing clinical and epidemiological issues regarding shigellosis. Supplementary Information The online version contains supplementary material available at 10.1186/s12866-021-02277-0.
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Affiliation(s)
- Zhen Zhu
- Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, 730050, Lanzhou, China.,College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Weiwei Wang
- Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, 730050, Lanzhou, China
| | - Mingze Cao
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Qiqi Zhu
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Tenghe Ma
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Yongying Zhang
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Guanhui Liu
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Xuzheng Zhou
- Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, 730050, Lanzhou, China
| | - Bing Li
- Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, 730050, Lanzhou, China
| | - Yuxiang Shi
- College of Life Science and Food Engineering, Hebei University of Engineering, Hanshan District, 056038, Handan, China
| | - Jiyu Zhang
- Key Laboratory of New Animal Drug Project of Gansu Province, Key Laboratory of Veterinary Pharmaceutical Development of the Ministry of Agriculture, Lanzhou Institute of Husbandry and Pharmaceutical Sciences of CAAS, Jiangouyan, Qilihe District, 730050, Lanzhou, China.
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6
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Enteropathogenic Infections: Organoids Go Bacterial. Stem Cells Int 2021; 2021:8847804. [PMID: 33505475 PMCID: PMC7810537 DOI: 10.1155/2021/8847804] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/06/2020] [Accepted: 12/16/2020] [Indexed: 12/13/2022] Open
Abstract
Enteric infections represent a major health care challenge which is particularly prevalent in countries with restricted access to clean water and sanitation and lacking personal hygiene precautions, altogether facilitating fecal-oral transmission of a heterogeneous spectrum of enteropathogenic microorganisms. Among these, bacterial species are responsible for a considerable proportion of illnesses, hospitalizations, and fatal cases, all of which have been continuously contributing to ignite researchers' interest in further exploring their individual pathogenicity. Beyond the universally accepted animal models, intestinal organoids are increasingly valued for their ability to mimic key architectural and physiologic features of the native intestinal mucosa. As a consequence, they are regarded as the most versatile and naturalistic in vitro model of the gut, allowing monitoring of adherence, invasion, intracellular trafficking, and propagation as well as repurposing components of the host cell equipment. At the same time, infected intestinal organoids allow close characterization of the host epithelium's immune response to enteropathogens. In this review, (i) we provide a profound update on intestinal organoid-based tissue engineering, (ii) we report the latest pathophysiological findings defining the infected intestinal organoids, and (iii) we discuss the advantages and limitations of this in vitro model.
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Parmar KM, Sinha SK, Prasad RS, Jogi MS, Laloo D, Dhobi M, Gurav SS, Prasad SK. Identifying the mechanism of eriosematin E from Eriosema chinense Vogel. for its antidiarrhoeal potential against Shigella flexneri-induced diarrhoea using in vitro, in vivo and in silico models. Microb Pathog 2020; 149:104582. [PMID: 33086104 DOI: 10.1016/j.micpath.2020.104582] [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: 08/10/2020] [Revised: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 11/19/2022]
Abstract
The main objective of the present investigation was to mechanistically evaluate the potency of the root extract (EEC), its bioactive chloroform fraction (CEC) and eriosematin E (ECM) isolated from Eriosema chinense against Shigella flexneri-induced sub-chronic model of infectious diarrhoea using in vitro, in vivo, and in silico methods. The in vitro antibacterial activity against pathogenic strain of S. flexneri demonstrated maximum effect of ECM followed by CEC and EEC in inhibiting growth of bacteria. Further, for in vivo evaluation, was carried out by inducing diarrhoea to the rats by administering oral suspension of S. flexneri to the animals, which was followed by treatment for a period of 6 days. EEC at 200, CEC at 100 and ECM at 10 mg/kg, p.o. showed promising effect, where EEC and ECM were found to be more effective showing maximum % protection on 6th day. Results also demonstrated a significant restoration of altered antioxidants, pro-inflammatory cytokines (IL-1β and TNF-α) expression, electrolyte balance, Na+/K+-ATPase activity and was also supported by histopathological examinations. Molecular docking study revealed that, eriosematin E inactivated the protease activity of SepA, a protein secreted by Shigella, which is responsible for disruption of epithelial barrier integrity. Thus, the overall observation confirmed the role of eriosematin E from E. chinense in treatment of Shigella flexneri-induced infectious diarrhoea.
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Affiliation(s)
- Komal M Parmar
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra, 440033, India
| | - Saurabh K Sinha
- Department of Pharmaceutical Sciences, Mohanlal Shukhadia University, Udaipur, Rajasthan, 313001, India
| | - Rupali S Prasad
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra, 440033, India
| | - Mohit S Jogi
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra, 440033, India
| | - Damiki Laloo
- Girijananda Chowdhury Institute of Pharmaceutical Sciences, Guwahati, Assam, India
| | - Mahaveer Dhobi
- Department of Pharmacognosy and Phytochemistry, Delhi Pharmaceutical Sciences and Research University, New Delhi, India
| | - Shailendra S Gurav
- Goa College of Pharmacy, Department of Pharmacognosy, Panaji, Goa University, Goa, 403001, India
| | - Satyendra K Prasad
- Department of Pharmaceutical Sciences, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur, Maharashtra, 440033, India.
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Whelan R, McVicker G, Leo JC. Staying out or Going in? The Interplay between Type 3 and Type 5 Secretion Systems in Adhesion and Invasion of Enterobacterial Pathogens. Int J Mol Sci 2020; 21:E4102. [PMID: 32521829 PMCID: PMC7312957 DOI: 10.3390/ijms21114102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 12/12/2022] Open
Abstract
Enteric pathogens rely on a variety of toxins, adhesins and other virulence factors to cause infections. Some of the best studied pathogens belong to the Enterobacterales order; these include enteropathogenic and enterohemorrhagic Escherichia coli, Shigella spp., and the enteropathogenic Yersiniae. The pathogenesis of these organisms involves two different secretion systems, a type 3 secretion system (T3SS) and type 5 secretion systems (T5SSs). The T3SS forms a syringe-like structure spanning both bacterial membranes and the host cell plasma membrane that translocates toxic effector proteins into the cytoplasm of the host cell. T5SSs are also known as autotransporters, and they export part of their own polypeptide to the bacterial cell surface where it exerts its function, such as adhesion to host cell receptors. During infection with these enteropathogens, the T3SS and T5SS act in concert to bring about rearrangements of the host cell cytoskeleton, either to invade the cell, confer intracellular motility, evade phagocytosis or produce novel structures to shelter the bacteria. Thus, in these bacteria, not only the T3SS effectors but also T5SS proteins could be considered "cytoskeletoxins" that bring about profound alterations in host cell cytoskeletal dynamics and lead to pathogenic outcomes.
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Affiliation(s)
| | | | - Jack C. Leo
- Antimicrobial Resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham NG1 4FQ, UK; (R.W.); (G.M.)
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9
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Quercetin a major biomarker of Psidium guajava L. inhibits SepA protease activity of Shigella flexneri in treatment of infectious diarrhoea. Microb Pathog 2019; 138:103807. [PMID: 31629796 DOI: 10.1016/j.micpath.2019.103807] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/15/2019] [Accepted: 10/15/2019] [Indexed: 02/07/2023]
Abstract
The leaves of the plant Psidium guajava L. (Myrtaceae) has been traditionally used in treatment of various gastrointestinal disorders including diarrhoea and have also been reported for its potent antidiarrhoeal activity on various chemical induced diarrhoea models. The objective of our present study was to evaluate the potency of the leaf extract of the plant Psidium guajava (PGE) along with its major biomarker quercetin against Shigella flexneri-induced sub chronic model of infectious diarrhoea. PGE at 100, 200 and 400 mg/kg, p.o. and quercetin at 50 mg/kg, p.o. were administered to Shigella flexneri-induced diarrhoeal rats for five days and various behavioural parameters were evaluated on 1st, 3rd and 5th day of treatment. This was followed by assessment of stool water content, density of Shigella flexneri in stools and blood parameters examination. After treatment, colon and small intestine of rats was dissected and subjected to biochemical estimations, cytokine profiling, antioxidant evaluations, ion concentration determination, Na+/K+-ATPase activity and histopathology. Molecular docking studies on crystal structure of Secreted Extracellular Protein A (SepA) from Shigella flexneri with biomarker quercetin was also performed. PGE at 200 mg/kg followed by quercetin depicted maximum antidiarrhoeal potential, which was confirmed through diarrhoea score and % protection, while PGE at 400 mg/kg showed similar effect to PGE 200 mg/kg thus, the later may have ceiling effect. PGE and quercetin also significantly reduced the density of Shigella flexneri in stools, water content of stools and restored the alterations observed in blood parameters, antioxidant status and pro-inflammatory cytokines (IL-6 and TNF-α) expression. These parameters contributed in normalization of electrolyte balance, reactivation of Na+/K+-ATPase activity and repairing of epithelial tissue damage, confirmed through histopathology. Docking simulation studies revealed the role of quercetin in inactivating the protease activity of SepA, a protein secreted by Shigella, which disrupts epithelial barrier integrity during infection and also manages its signal production. Thus, the overall results confirmed the role of quercetin as a major biomarker for the observed antidiarrhoeal potential of P. guajava against Shigella flexneri induced infectious diarrhoea.
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10
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McVicker G, Hollingshead S, Pilla G, Tang CM. Maintenance of the virulence plasmid in Shigella flexneri is influenced by Lon and two functional partitioning systems. Mol Microbiol 2019; 111:1355-1366. [PMID: 30767313 PMCID: PMC6519299 DOI: 10.1111/mmi.14225] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/10/2019] [Indexed: 11/30/2022]
Abstract
Members of the genus Shigella carry a large plasmid, pINV, which is essential for virulence. In Shigella flexneri, pINV harbours three toxin‐antitoxin (TA) systems, CcdAB, GmvAT and VapBC that promote vertical transmission of the plasmid. Type II TA systems, such as those on pINV, consist of a toxic protein and protein antitoxin. Selective degradation of the antitoxin by proteases leads to the unopposed action of the toxin once genes encoding a TA system have been lost, such as following failure to inherit a plasmid harbouring a TA system. Here, we investigate the role of proteases in the function of the pINV TA systems and demonstrate that Lon, but not ClpP, is required for their activity during plasmid stability. This provides the first evidence that acetyltransferase family TA systems, such as GmvAT, can be regulated by Lon. Interestingly, S. flexneri pINV also harbours two putative partitioning systems, ParAB and StbAB. We show that both systems are functional for plasmid maintenance although their activity is masked by other systems on pINV. Using a model vector based on the pINV replicon, we observe temperature‐dependent differences between the two partitioning systems that contribute to our understanding of the maintenance of virulence in Shigella species.
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Affiliation(s)
- Gareth McVicker
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Sarah Hollingshead
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Giulia Pilla
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
| | - Christoph M Tang
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford, OX1 3RE, UK
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11
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Kalindamar S, Lu J, Abdelhamed H, Tekedar HC, Lawrence ML, Karsi A. Transposon mutagenesis and identification of mutated genes in growth-delayed Edwardsiella ictaluri. BMC Microbiol 2019; 19:55. [PMID: 30849940 PMCID: PMC6408766 DOI: 10.1186/s12866-019-1429-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 02/27/2019] [Indexed: 01/23/2023] Open
Abstract
Background Edwardsiella ictaluri is a Gram-negative facultative intracellular anaerobe and the etiologic agent of enteric septicemia of channel catfish (ESC). To the catfish industry, ESC is a devastating disease due to production losses and treatment costs. Identification of virulence mechanisms of E. ictaluri is critical to developing novel therapeutic approaches for the disease. Here, we report construction of a transposon insertion library and identification of mutated genes in growth-delayed E. ictaluri colonies. We also provide safety and efficacy of transposon insertion mutants in catfish. Results An E. ictaluri transposon insertion library with 45,000 transposants and saturating 30.92% of the TA locations present in the E. ictaluri genome was constructed. Transposon end mapping of 250 growth-delayed E. ictaluri colonies and bioinformatic analysis of sequences revealed 56 unique E. ictaluri genes interrupted by the MAR2xT7 transposon, which are involved in metabolic and cellular processes and mostly localized in the cytoplasm or cytoplasmic membrane. Of the 56 genes, 30 were associated with bacterial virulence. Safety and vaccine efficacy testing of 19 mutants showed that mutants containing transposon insertions in hypothetical protein (Eis::004), and Fe-S cluster assembly protein (IscX, Eis::039), sulfurtransferase (TusA, Eis::158), and universal stress protein A (UspA, Eis::194) were safe and provided significant protection (p < 0.05) against wild-type E. ictaluri. Conclusions The results indicate that random transposon mutagenesis causing growth-delayed phenotype results in identification bacterial virulence genes, and attenuated strains with transposon interrupted virulence genes could be used as vaccine to activate fish immune system.
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Affiliation(s)
- Safak Kalindamar
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Jingjun Lu
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Hossam Abdelhamed
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Hasan C Tekedar
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Mark L Lawrence
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA
| | - Attila Karsi
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, USA.
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12
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Mannion AJ, Martin HR, Shen Z, Buckley EM, Dzink-Fox JL, Garcia A, Marini RP, Patterson MM, Fox JG. Plasmid-Mediated Quinolone Resistance in Shigella flexneri Isolated From Macaques. Front Microbiol 2018; 9:311. [PMID: 29556221 PMCID: PMC5844971 DOI: 10.3389/fmicb.2018.00311] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 02/09/2018] [Indexed: 12/02/2022] Open
Abstract
Non-human primates (NHPs) for biomedical research are commonly infected with Shigella spp. that can cause acute dysentery or chronic episodic diarrhea. These animals are often prophylactically and clinically treated with quinolone antibiotics to eradicate these possible infections. However, chromosomally- and plasmid-mediated antibiotic resistance has become an emerging concern for species in the family Enterobacteriaceae. In this study, five individual isolates of multi-drug resistant Shigella flexneri were isolated from the feces of three macaques. Antibiotic susceptibility testing confirmed resistance or decreased susceptibility to ampicillin, amoxicillin-clavulanic acid, cephalosporins, gentamicin, tetracycline, ciprofloxacin, enrofloxacin, levofloxacin, and nalidixic acid. S. flexneri isolates were susceptible to trimethoprim-sulfamethoxazole, and this drug was used to eradicate infection in two of the macaques. Plasmid DNA from all isolates was positive for the plasmid-encoded quinolone resistance gene qnrS, but not qnrA and qnrB. Conjugation and transformation of plasmid DNA from several S. flexneri isolates into antibiotic-susceptible Escherichia coli strains conferred the recipients with resistance or decreased susceptibility to quinolones and beta-lactams. Genome sequencing of two representative S. flexneri isolates identified the qnrS gene on a plasmid-like contig. These contigs showed >99% homology to plasmid sequences previously characterized from quinolone-resistant Shigella flexneri 2a and Salmonella enterica strains. Other antibiotic resistance genes and virulence factor genes were also identified in chromosome and plasmid sequences in these genomes. The findings from this study indicate macaques harbor pathogenic S. flexneri strains with chromosomally- and plasmid-encoded antibiotic resistance genes. To our knowledge, this is the first report of plasmid-mediated quinolone resistance in S. flexneri isolated from NHPs and warrants isolation and antibiotic testing of enteric pathogens before treating macaques with quinolones prophylactically or therapeutically.
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Affiliation(s)
- Anthony J Mannion
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Heather R Martin
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Zeli Shen
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Ellen M Buckley
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - JoAnn L Dzink-Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Alexis Garcia
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Robert P Marini
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Mary M Patterson
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
| | - James G Fox
- Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA, United States
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13
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Belotserkovsky I, Sansonetti PJ. Shigella and Enteroinvasive Escherichia Coli. Curr Top Microbiol Immunol 2018; 416:1-26. [PMID: 30218158 DOI: 10.1007/82_2018_104] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Shigella and enteroinvasive Escherichia coli (EIEC) are gram-negative bacteria responsible for bacillary dysentery (shigellosis) in humans, which is characterized by invasion and inflammatory destruction of the human colonic epithelium. Different EIEC and Shigella subgroups rose independently from commensal E. coli through patho-adaptive evolution that included loss of functional genes interfering with the virulence and/or with the intracellular lifestyle of the bacteria, as well as acquisition of genetic elements harboring virulence genes. Among the latter is the large virulence plasmid encoding for a type three secretion system (T3SS), which enables translocation of virulence proteins (effectors) from the bacterium directly into the host cell cytoplasm. These effectors enable the pathogen to subvert epithelial cell functions, promoting its own uptake, replication in the host cytosol, and dissemination to adjacent cells while concomitantly inhibiting pro-inflammatory cell death. Furthermore, T3SS effectors are directly involved in Shigella manipulation of immune cells causing their dysfunction and promoting cell death. In the current chapter, we first describe the evolution of the enteroinvasive pathovars and then summarize the overall knowledge concerning the pathogenesis of these bacteria, with a particular focus on Shigella flexneri. Subversion of host cell functions in the human gut, both epithelial and immune cells, by different virulence factors is especially highlighted.
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Affiliation(s)
- Ilia Belotserkovsky
- Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 28 Rue Du Dr Roux, 75724 Cedex 15, Paris, France.
| | - Philippe J Sansonetti
- Microbiologie et Maladies Infectieuses, Collège de France, 11 Place Marcelin Berthelot, 75005, Paris, France
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14
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Medeiros PHQS, Lima AÂM, Guedes MM, Havt A, Bona MD, Rey LC, Soares AM, Guerrant RL, Weigl BH, Lima IFN. Molecular characterization of virulence and antimicrobial resistance profile of Shigella species isolated from children with moderate to severe diarrhea in northeastern Brazil. Diagn Microbiol Infect Dis 2017; 90:198-205. [PMID: 29217418 DOI: 10.1016/j.diagmicrobio.2017.11.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/08/2017] [Accepted: 11/01/2017] [Indexed: 12/28/2022]
Abstract
Molecular characterization of virulence and antimicrobial resistance profiles were determined for Shigella species isolated from children with diarrhea in Fortaleza, Brazil. Fecal specimens were collected along with socioeconomic and clinical data from children with moderate to severe diarrhea requiring emergency care. Shigella spp. were isolated by standard microbiological techniques, and we developed 4 multiplex polymerase chain reaction assays to detect 16 virulence-related genes (VRGs). Antimicrobial susceptibility tests were performed using disk diffusion assays. S. flexneri and S. sonnei were the predominant serogroups. S. flexneri was associated with low monthly incomes; more severe disease; higher number of VRGs; and presence of pic, set, and sepA genes. The SepA gene was associated with more intense abdominal pain. S. flexneri was correlated with resistance to ampicillin and chloramphenicol, whereas S. sonnei was associated with resistance to azithromycin. Strains harboring higher numbers of VRGs were associated with resistance to more antimicrobials. We highlight the correlation between presence of S. flexneri and sepA, and increased virulence and suggest a link to socioeconomic change in northeastern Brazil. Additionally, antimicrobial resistance was associated with serogroup specificity in Shigella spp. and increased bacterial VRGs.
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Affiliation(s)
| | - Aldo Ângelo Moreira Lima
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil; Center for Global Health, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | - Marjorie Moreira Guedes
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Alexandre Havt
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Mariana Duarte Bona
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Luís Carlos Rey
- Department of Mother and Child Health, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Alberto Melo Soares
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil
| | - Richard Littleton Guerrant
- Center for Global Health, Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, VA, USA
| | - Bernhard H Weigl
- Program for Appropriate Technology in Health (PATH), Seattle, WA, USA
| | - Ila Fernanda Nunes Lima
- Institute of Biomedicine for Brazilian Semi-Arid (IBISAB), Department of Physiology and Pharmacology, Federal University of Ceara, Fortaleza, CE, Brazil
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15
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Yaghoubi S, Ranjbar R, Dallal MMS, Fard SY, Shirazi MH, Mahmoudi M. Profiling of Virulence-associated Factors in Shigella Species Isolated from Acute Pediatric Diarrheal Samples in Tehran, Iran. Osong Public Health Res Perspect 2017; 8:220-226. [PMID: 28781945 PMCID: PMC5525559 DOI: 10.24171/j.phrp.2017.8.3.09] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Revised: 05/23/2017] [Accepted: 05/28/2017] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The genus Shigella comprises the most infectious and diarrheagenic bacteria causing severe diseases, mostly in children under five years of age. This study aimed to detect nine virulence genes (ipaBCD, VirA, sen, set1A, set1B, ial, ipaH, stx, and sat) in Shigella species (spp.) using multiplex polymerase chain reaction (MPCR) and to determine the relation of Shigella spp. from pediatric diarrheal samples with hospitalization and bloody diarrhea in Tehran, Iran. METHODS Shigella spp. were isolated and identified using standard microbiological and serological methods. The virulence genes were detected using MPCR. RESULTS Seventy-five Shigella spp. (40 S. sonnei, 33 S. flexneri, 1 S. dysenteriae, and 1 S. boydii) were isolated in this study. The prevalence of ial, sen, sat, set1A, and set1B was 74.7%, 45.4%, 28%, 24%, and 24%, respectively. All S. flexneri isolates, while no S. sonnei, S. dysenteriae, or S. boydii isolates, contained sat, set1A, and set1B. All isolates were positive for ipaH, ipaBCD, and virA, while one (1.4%) of the isolates contained stx. The highest prevalence of virulence determinants was found in S. flexneri serotype IIa. Nineteen (57.6%) of 33 S. flexneri isolates were positive for ipaBCD, ipaH, virA, ial, and sat. The sen determinants were found to be statistically significantly associated with hospitalization and bloody diarrhea (p = 0.001). CONCLUSION This study revealed a high prevalence of enterotoxin genes in S. flexneri, especially in serotype 2a, and has presented relations between a few clinical features of shigellosis and numerous virulence determinants of clinical isolates of Shigella spp.
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Affiliation(s)
- Sajad Yaghoubi
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Reza Ranjbar
- Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Mohammad Mehdi Soltan Dallal
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.,Food Microbiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Somayeh Yasliani Fard
- Department of Microbiology and Immunology, Medical School, Alborz University of Medical Sciences, Karaj, Iran
| | - Mohammad Hasan Shirazi
- Division of Microbiology, Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mahmood Mahmoudi
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
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16
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Mattock E, Blocker AJ. How Do the Virulence Factors of Shigella Work Together to Cause Disease? Front Cell Infect Microbiol 2017; 7:64. [PMID: 28393050 PMCID: PMC5364150 DOI: 10.3389/fcimb.2017.00064] [Citation(s) in RCA: 140] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 02/21/2017] [Indexed: 01/01/2023] Open
Abstract
Shigella is the major cause of bacillary dysentery world-wide. It is divided into four species, named S. flexneri, S. sonnei, S. dysenteriae, and S. boydii, which are distinct genomically and in their ability to cause disease. Shigellosis, the clinical presentation of Shigella infection, is characterized by watery diarrhea, abdominal cramps, and fever. Shigella's ability to cause disease has been attributed to virulence factors, which are encoded on chromosomal pathogenicity islands and the virulence plasmid. However, information on these virulence factors is not often brought together to create a detailed picture of infection, and how this translates into shigellosis symptoms. Firstly, Shigella secretes virulence factors that induce severe inflammation and mediate enterotoxic effects on the colon, producing the classic watery diarrhea seen early in infection. Secondly, Shigella injects virulence effectors into epithelial cells via its Type III Secretion System to subvert the host cell structure and function. This allows invasion of epithelial cells, establishing a replicative niche, and causes erratic destruction of the colonic epithelium. Thirdly, Shigella produces effectors to down-regulate inflammation and the innate immune response. This promotes infection and limits the adaptive immune response, causing the host to remain partially susceptible to re-infection. Combinations of these virulence factors may contribute to the different symptoms and infection capabilities of the diverse Shigella species, in addition to distinct transmission patterns. Further investigation of the dominant species causing disease, using whole-genome sequencing and genotyping, will allow comparison and identification of crucial virulence factors and may contribute to the production of a pan-Shigella vaccine.
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Affiliation(s)
- Emily Mattock
- Faculty of Biomedical Sciences, Schools of Cellular and Molecular Medicine and Biochemistry, University of Bristol Bristol, UK
| | - Ariel J Blocker
- Faculty of Biomedical Sciences, Schools of Cellular and Molecular Medicine and Biochemistry, University of Bristol Bristol, UK
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17
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Faherty CS, Wu T, Morris CR, Grassel CL, Rasko DA, Harper JM, Shea-Donohue T, Fasano A, Barry EM. The synthesis of OspD3 (ShET2) in Shigella flexneri is independent of OspC1. Gut Microbes 2016; 7:486-502. [PMID: 27657187 PMCID: PMC5103656 DOI: 10.1080/19490976.2016.1239682] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Shigella flexneri is a Gram-negative pathogen that invades the colonic epithelium and causes millions of cases of watery diarrhea or bacillary dysentery predominately in children under the age of 5 years in developing countries. The effector Shigella enterotoxin 2 (ShET2), or OspD3, is encoded by the sen or ospD3 gene on the virulence plasmid. Previous literature has suggested that ospD3 is in an operon downstream of the ospC1 gene, and expression of both genes is controlled by a promoter upstream of ospC1. Since the intergenic region is 328 bases in length and contains several putative promoter regions, we hypothesized the genes are independently expressed. Here we provide data that ospD3 and ospC1 are not co-transcribed and that OspC1 is not required for OspD3/ShET2 function. Most importantly, we identified strong promoter activity in the intergenic region and demonstrate that OspD3/ShET2 can be expressed and secreted independently of OspC1. This work increases our understanding of the synthesis of a unique virulence factor and provides further insights into Shigella pathogenesis.
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Affiliation(s)
- Christina S. Faherty
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland,Department of Pediatrics, Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Boston, Massachusetts,CONTACT Christina S. Faherty Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, 114 16th Street (114-3503), Charlestown, MA, 02129
| | - Tao Wu
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland
| | - Carolyn R. Morris
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland,Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland
| | - Christen L. Grassel
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland
| | - David A. Rasko
- Department of Microbiology and Immunology, Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jill M. Harper
- Department of Medicine, Mucosal Biology Research Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Terez Shea-Donohue
- Department of Medicine, Mucosal Biology Research Center, University of Maryland School of Medicine, Baltimore, Maryland
| | - Alessio Fasano
- Department of Pediatrics, Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Boston, Massachusetts
| | - Eileen M. Barry
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland
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18
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Newton P, Latomanski EA, Newton HJ. Applying Fluorescence Resonance Energy Transfer (FRET) to Examine Effector Translocation Efficiency by Coxiella burnetii during siRNA Silencing. J Vis Exp 2016. [PMID: 27501079 DOI: 10.3791/54210] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Coxiella burnetii, the causative agent of Q fever, is an intracellular pathogen that relies on a Type IV Dot/Icm Secretion System to establish a replicative niche. A cohort of effectors are translocated through this system into the host cell to manipulate host processes and allow the establishment of a unique lysosome-derived vacuole for replication. The method presented here involves the combination of two well-established techniques: specific gene silencing using siRNA and measurement of effector translocation using a FRET-based substrate that relies on β-lactamase activity. Applying these two approaches, we can begin to understand the role of host factors in bacterial secretion system function and effector translocation. In this study we examined the role of Rab5A and Rab7A, both important regulators of the endocytic trafficking pathway. We demonstrate that silencing the expression of either protein results in a decrease in effector translocation efficiency. These methods can be easily modified to examine other intracellular and extracellular pathogens that also utilize secretion systems. In this way, a global picture of host factors involved in bacterial effector translocation may be revealed.
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Affiliation(s)
- Patrice Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne
| | - Eleanor A Latomanski
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne
| | - Hayley J Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne;
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19
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Identification and Characterization of Putative Translocated Effector Proteins of the Edwardsiella ictaluri Type III Secretion System. mSphere 2016; 1:mSphere00039-16. [PMID: 27303737 PMCID: PMC4888880 DOI: 10.1128/msphere.00039-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 03/25/2016] [Indexed: 01/12/2023] Open
Abstract
The bacterial pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), an economically significant disease of farm-raised channel catfish. Commercial catfish production accounts for the majority of the total fin fish aquaculture in the United States, with almost 300,000 tons produced annually, and ESC is the leading cause of disease loss in the industry. We have demonstrated the survival and replication of E. ictaluri within channel catfish cells and identified a secretion system that is essential for E. ictaluri intracellular replication and virulence. We have also identified nine proteins encoded in the E. ictaluri genome that we believe are actively transferred from the bacterium to the cytoplasm of the host cell and act to manipulate host cell physiology to the advantage of the bacterium. The data presented here confirm that the proteins are actually transferred during an infection, which will lead to further work on approaches to preventing or controlling ESC. Edwardsiella ictaluri, a major pathogen in channel catfish aquaculture, encodes a type III secretion system (T3SS) that is essential for intracellular replication and virulence. Previous work identified three putative T3SS effectors in E. ictaluri, and in silico analysis of the E. ictaluri genome identified six additional putative effectors, all located on the chromosome outside the T3SS pathogenicity island. To establish active translocation by the T3SS, we constructed translational fusions of each effector to the amino-terminal adenylate cyclase (AC) domain of the Bordetella pertussis adenylate cyclase toxin CyaA. When translocated through the membrane of the Edwardsiella-containing vacuole (ECV), the cyclic AMP produced by the AC domain in the presence of calmodulin in the host cell cytoplasm can be measured. Results showed that all nine effectors were translocated from E. ictaluri in the ECV to the cytoplasm of the host cells in the wild-type strain but not in a T3SS mutant, indicating that translocation is dependent on the T3SS machinery. This confirms that the E. ictaluri T3SS is similar to the Salmonella pathogenicity island 2 T3SS in that it translocates effectors through the membrane of the bacterial vacuole directly into the host cell cytoplasm. Additional work demonstrated that both initial acidification and subsequent neutralization of the ECV were necessary for effector translocation, except for two of them that did not require neutralization. Single-gene mutants constructed for seven of the individual effectors were all attenuated for replication in CCO cells, but only three were replication deficient in head kidney-derived macrophages (HKDM). IMPORTANCE The bacterial pathogen Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), an economically significant disease of farm-raised channel catfish. Commercial catfish production accounts for the majority of the total fin fish aquaculture in the United States, with almost 300,000 tons produced annually, and ESC is the leading cause of disease loss in the industry. We have demonstrated the survival and replication of E. ictaluri within channel catfish cells and identified a secretion system that is essential for E. ictaluri intracellular replication and virulence. We have also identified nine proteins encoded in the E. ictaluri genome that we believe are actively transferred from the bacterium to the cytoplasm of the host cell and act to manipulate host cell physiology to the advantage of the bacterium. The data presented here confirm that the proteins are actually transferred during an infection, which will lead to further work on approaches to preventing or controlling ESC.
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20
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The roles of the virulence factor IpaB in Shigella spp. in the escape from immune cells and invasion of epithelial cells. Microbiol Res 2015; 181:43-51. [PMID: 26640051 DOI: 10.1016/j.micres.2015.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 08/24/2015] [Accepted: 08/29/2015] [Indexed: 02/08/2023]
Abstract
Shigellosis is an acute invasive enteric infection by the Gram negative pathogen Shigella, which causes human diarrhea. Shigella, which are highly epidemic and pathogenic, have become a serious public health problem. The virulence plasmid is a large plasmid essential to the infected host cells. Many virulence factors are encoded in the ipa-mxi-spa region by the virulence plasmid. IpaB is a multifunctional and essential virulence factor in the infection process. In this review article, we introduce the recent studies of the effect of IpaB in Shigella-infected host cells. IpaB is involved in a type III secretion system (T3SS) structure. It also controls the secretion of virulence factors and Shigella adhesion to host cells. In addition, it forms the ion pore, destroys phagosomes, and induces the immune cell's apoptosis or necrosis. Moreover, IpaB can become a potential antigen for Shigella vaccine development.
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21
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Mirzarazi M, Rezatofighi SE, Pourmahdi M, Mohajeri MR. Occurrence of genes encoding enterotoxins in uropathogenic Escherichia coli isolates. Braz J Microbiol 2015. [PMID: 26221102 PMCID: PMC4512059 DOI: 10.1590/s1517-838246120130860] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To determine the presence of some toxins of diarrheagenic Escherichia coli
(DEC) in uropathogenic E. coli
(UPEC), 138 urinary tract infection (UTI)-causing UPECs were analyzed. The astA
, set
, sen
and cdtB
genes were detected in 13 (9.4%), 2 (1.3%), 13 (9.4%) and 0 (0%) of UPEC isolates respectively. The results show that some genes encoding toxins can be transferred from DEC pathotypes to UPECs therefore these isolates can transform into potential diarrhea-causing agents.
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Affiliation(s)
- Mahsa Mirzarazi
- Department of Biology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran
| | | | - Mahdi Pourmahdi
- Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran
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22
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Walker RI. An assessment of enterotoxigenic Escherichia coli and Shigella vaccine candidates for infants and children. Vaccine 2014; 33:954-65. [PMID: 25482842 DOI: 10.1016/j.vaccine.2014.11.049] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2014] [Revised: 11/25/2014] [Accepted: 11/27/2014] [Indexed: 02/06/2023]
Abstract
Despite improvements to water quality, sanitation, and the implementation of current prevention and treatment interventions, diarrhea remains a major cause of illness and death, especially among children less than five years of age in the developing world. Rotavirus vaccines have already begun making a real impact on diarrhea, but several more enteric vaccines will be necessary to achieve broader reductions of illness and death. Among the many causes of diarrheal disease, enterotoxigenic Escherichia coli (ETEC) and Shigella are the two most important bacterial pathogens for which there are no currently licensed vaccines. Vaccines against these two pathogens could greatly reduce the impact of disease caused by these infections. This review describes the approaches to ETEC and Shigella vaccines that are currently under development, including a range of both cellular and subunit approaches for each pathogen. In addition, the review discusses strategies for maximizing the potential benefit of these vaccines, which includes the feasibility of co-administration, consolidation, and combination of vaccine candidates, as well as issues related to effective administration of enteric vaccines to infants. Recent impact studies indicate that ETEC and Shigella vaccines could significantly benefit global public health. Either vaccine, particularly if they could be combined together or with another enteric vaccine, would be an extremely valuable tool for saving lives and promoting the health of infants and children in the developing world, as well as potentially providing protection to travelers and military personnel visiting endemic areas.
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Affiliation(s)
- Richard I Walker
- PATH, 455 Massachusetts Avenue NW, Suite 1000, Washington, DC 20001, USA.
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23
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Virulence factors associated with pediatric shigellosis in Brazilian Amazon. BIOMED RESEARCH INTERNATIONAL 2014; 2014:539697. [PMID: 24877110 PMCID: PMC4020526 DOI: 10.1155/2014/539697] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 04/09/2014] [Indexed: 11/29/2022]
Abstract
Shigellosis is a global human health problem and the incidence is highest among children. In the present work, main Shigella virulence genes was examined by PCR and compared to symptoms of pediatric shigellosis. Thirty Shigella isolates were identified from an etiologic study at which 1,339 children ranging 0–10 years old were enrolled. S. flexneri was the most frequent species reaching 60.0% of isolates, 22.2% were S. sonnei, and 6.6% were both S. dysenteriae and S. boydii. All Shigella infected children had diarrhea, but not all were accompanied by others symptoms of bacillary dysentery. Among major virulence genes, the PCR typing revealed ipaBCD was present in all isolates, followed by IpaH7.8, set-1A, set-1B, sen/ospD3, virF, and invE. The pathogenic potential of the ShET-1B subunit was observed in relation to dehydration (P < 0.001) and ShET-2 related to the intestinal injury (P = 0.033) evidenced by the presence of bloody diarrhea. Our results show associations among symptoms of shigellosis and virulence genes of clinical isolates of Shigella spp.
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24
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Pathogenesis of human enterovirulent bacteria: lessons from cultured, fully differentiated human colon cancer cell lines. Microbiol Mol Biol Rev 2014; 77:380-439. [PMID: 24006470 DOI: 10.1128/mmbr.00064-12] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Hosts are protected from attack by potentially harmful enteric microorganisms, viruses, and parasites by the polarized fully differentiated epithelial cells that make up the epithelium, providing a physical and functional barrier. Enterovirulent bacteria interact with the epithelial polarized cells lining the intestinal barrier, and some invade the cells. A better understanding of the cross talk between enterovirulent bacteria and the polarized intestinal cells has resulted in the identification of essential enterovirulent bacterial structures and virulence gene products playing pivotal roles in pathogenesis. Cultured animal cell lines and cultured human nonintestinal, undifferentiated epithelial cells have been extensively used for understanding the mechanisms by which some human enterovirulent bacteria induce intestinal disorders. Human colon carcinoma cell lines which are able to express in culture the functional and structural characteristics of mature enterocytes and goblet cells have been established, mimicking structurally and functionally an intestinal epithelial barrier. Moreover, Caco-2-derived M-like cells have been established, mimicking the bacterial capture property of M cells of Peyer's patches. This review intends to analyze the cellular and molecular mechanisms of pathogenesis of human enterovirulent bacteria observed in infected cultured human colon carcinoma enterocyte-like HT-29 subpopulations, enterocyte-like Caco-2 and clone cells, the colonic T84 cell line, HT-29 mucus-secreting cell subpopulations, and Caco-2-derived M-like cells, including cell association, cell entry, intracellular lifestyle, structural lesions at the brush border, functional lesions in enterocytes and goblet cells, functional and structural lesions at the junctional domain, and host cellular defense responses.
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Zaidi MB, Estrada-García T. Shigella: A Highly Virulent and Elusive Pathogen. CURRENT TROPICAL MEDICINE REPORTS 2014; 1:81-87. [PMID: 25110633 DOI: 10.1007/s40475-014-0019-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Despite a significant decrease in Shigella-related mortality, shigellosis continues to carry a significant burden of disease worldwide, particularly in Asia and Africa. Shigella is a highly virulent pathogen comprised of four major species with numerous subtypes. Shigella dysenteriae and Shigella flexneri infections are predominant in resource-limited settings. Clinical presentations range from mild watery diarrhea to severe dysentery with systemic complications such as electrolyte imbalance, seizures and hemolytic uremic syndrome. S. dysenteriae subtype 1, the producer of Shiga toxin, causes the most severe illness and highest mortality. Susceptible strains of Shigella may be effectively treated with inexpensive oral antibiotics such as ampicillin or trimethoprim-sulfamethoxazole. Unfortunately, multidrug resistant strains have emerged that have rendered most antibiotics, including fluoroquinolones and extended-spectrum cephalosporins, ineffective. Management and prevention of shigellosis represents a major public health challenge. The development of an effective vaccine is urgently needed to decrease its global impact.
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Affiliation(s)
- Mussaret Bano Zaidi
- Microbiology Research Laboratory, Hospital General O'Horan, Av. Itzaes x Jacinto Canek, C.P. 97000 Mérida, Mexico. Phone and fax: +52-(999) 923-8673, ; Infectious Diseases Research Unit, Hospital Regional de Alta Especialidad de la Península de Yucatán, Km. 8.5 Carr. Merida-Cholul S/N, Col. Maya, C.P. 97134, Merida, Mexico
| | - Teresa Estrada-García
- Department of Molecular Biomedicine, CINVESTAV-IPN, Av. Instituto Politecnico Nacional 2508, San Pedro Zacatenco, C.P. 07360, Mexico City, Mexico. ,
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Fiorentino M, Levine MM, Sztein MB, Fasano A. Effect of wild-type Shigella species and attenuated Shigella vaccine candidates on small intestinal barrier function, antigen trafficking, and cytokine release. PLoS One 2014; 9:e85211. [PMID: 24416363 PMCID: PMC3887025 DOI: 10.1371/journal.pone.0085211] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 11/27/2013] [Indexed: 01/22/2023] Open
Abstract
Bacterial dysentery due to Shigella species is a major cause of morbidity and mortality worldwide. The pathogenesis of Shigella is based on the bacteria's ability to invade and replicate within the colonic epithelium, resulting in severe intestinal inflammatory response and epithelial destruction. Although the mechanisms of pathogenesis of Shigella in the colon have been extensively studied, little is known on the effect of wild-type Shigella on the small intestine and the role of the host response in the development of the disease. Moreover, to the best of our knowledge no studies have described the effects of apically administered Shigella flexneri 2a and S. dysenteriae 1 vaccine strains on human small intestinal enterocytes. The aim of this study was to assess the coordinated functional and immunological human epithelial responses evoked by strains of Shigella and candidate vaccines on small intestinal enterocytes. To model the interactions of Shigella with the intestinal mucosa, we apically exposed monolayers of human intestinal Caco2 cells to increasing bacterial inocula. We monitored changes in paracellular permeability, examined the organization of tight-junctions and the pro-inflammatory response of epithelial cells. Shigella infection of Caco2 monolayers caused severe mucosal damage, apparent as a drastic increase in paracellular permeability and disruption of tight junctions at the cell-cell boundary. Secretion of pro-inflammatory IL-8 was independent of epithelial barrier dysfunction. Shigella vaccine strains elicited a pro-inflammatory response without affecting the intestinal barrier integrity. Our data show that wild-type Shigella infection causes a severe alteration of the barrier function of a small intestinal cell monolayer (a proxy for mucosa) and might contribute (along with enterotoxins) to the induction of watery diarrhea. Diarrhea may be a mechanism by which the host attempts to eliminate harmful bacteria and transport them from the small to the large intestine where they invade colonocytes inducing a strong inflammatory response.
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Affiliation(s)
- Maria Fiorentino
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Myron M. Levine
- Center for Vaccine Development and the Departments of Pediatrics and Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Marcelo B. Sztein
- Center for Vaccine Development and the Departments of Pediatrics and Medicine, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alessio Fasano
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
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Croxen MA, Law RJ, Scholz R, Keeney KM, Wlodarska M, Finlay BB. Recent advances in understanding enteric pathogenic Escherichia coli. Clin Microbiol Rev 2013; 26:822-80. [PMID: 24092857 PMCID: PMC3811233 DOI: 10.1128/cmr.00022-13] [Citation(s) in RCA: 831] [Impact Index Per Article: 75.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Although Escherichia coli can be an innocuous resident of the gastrointestinal tract, it also has the pathogenic capacity to cause significant diarrheal and extraintestinal diseases. Pathogenic variants of E. coli (pathovars or pathotypes) cause much morbidity and mortality worldwide. Consequently, pathogenic E. coli is widely studied in humans, animals, food, and the environment. While there are many common features that these pathotypes employ to colonize the intestinal mucosa and cause disease, the course, onset, and complications vary significantly. Outbreaks are common in developed and developing countries, and they sometimes have fatal consequences. Many of these pathotypes are a major public health concern as they have low infectious doses and are transmitted through ubiquitous mediums, including food and water. The seriousness of pathogenic E. coli is exemplified by dedicated national and international surveillance programs that monitor and track outbreaks; unfortunately, this surveillance is often lacking in developing countries. While not all pathotypes carry the same public health profile, they all carry an enormous potential to cause disease and continue to present challenges to human health. This comprehensive review highlights recent advances in our understanding of the intestinal pathotypes of E. coli.
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Abstract
Renewed awareness of the substantial morbidity and mortality that Shigella infection causes among young children in developing countries, combined with technological innovations in vaccinology, has led to the development of novel vaccine strategies in the past 5 years. Along with advancement of classic vaccines in clinical trials and new sophisticated measurements of immunological responses, much new data has been produced, lending promise to the potential for production of safe and effective Shigella vaccines. Herein, we review the latest progress in Shigella vaccine development within the framework of persistent obstacles.
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Faherty C, Harper JM, Shea-Donohue T, Barry EM, Kaper JB, Fasano A, Nataro JP. Chromosomal and plasmid-encoded factors of Shigella flexneri induce secretogenic activity ex vivo. PLoS One 2012; 7:e49980. [PMID: 23166804 PMCID: PMC3500342 DOI: 10.1371/journal.pone.0049980] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2012] [Accepted: 10/15/2012] [Indexed: 12/22/2022] Open
Abstract
Shigella flexneri is a Gram-negative, facultative intracellular pathogen that causes millions of cases of watery or bloody diarrhea annually, resulting in significant global mortality. Watery diarrhea is thought to arise in the jejunum, and subsequent bloody diarrhea occurs as a result of invasion of the colonic epithelium. Previous literature has demonstrated that Shigella encodes enterotoxins, both chromosomally and on the 220 kilobase virulence plasmid. The ShigellaEnterotoxins 1 and 2 (ShET1 and ShET2) have been shown to increase water accumulation in the rabbit ileal loop model. In addition, these toxins increase the short circuit current in rabbit tissue mounted in Ussing chambers, which is a model for the ion exchange that occurs during watery diarrhea. In this study, we sought to validate the use of mouse jejunum in Ussing chamber as an alternative, more versatile model to study bacterial pathogenesis. In the process, we also identified enterotoxins in addition to ShET1 and ShET2 encoded by S. flexneri. Through analysis of proteins secreted from wildtype bacteria and various deletion mutants, we have identified four factors responsible for enterotoxin activity: ShET1 and Pic, which are encoded on the chromosome; ShET2 (encoded by sen or ospD3), which requires the type-III secretion system for secretion; and SepA, an additional factor encoded on the virulence plasmid. The use of mouse jejunum serves as a reliable and reproducible model to identify the enterotoxins elaborated by enteric bacteria. Moreover, the identification of all Shigella proteins responsible for enterotoxin activity is vital to our understanding of Shigella pathogenicity and to our success in developing safe and effective vaccine candidates.
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Affiliation(s)
- Christina Faherty
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Jill M. Harper
- Mucosal Biology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Terez Shea-Donohue
- Mucosal Biology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Eileen M. Barry
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - James B. Kaper
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alessio Fasano
- Mucosal Biology Research Center, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
| | - James P. Nataro
- Department of Medicine, Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
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Two live attenuated Shigella flexneri 2a strains WRSf2G12 and WRSf2G15: a new combination of gene deletions for 2nd generation live attenuated vaccine candidates. Vaccine 2012; 30:5159-71. [PMID: 22658966 DOI: 10.1016/j.vaccine.2012.05.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Revised: 04/25/2012] [Accepted: 05/01/2012] [Indexed: 11/23/2022]
Abstract
Shigella infections are a major cause of inflammatory diarrhea and dysentery worldwide. First-generation virG-based live attenuated Shigella strains have been successfully tested in phase I and II clinical trials and are a leading approach for Shigella vaccine development. Additional gene deletions in senA, senB and msbB2 have been engineered into second-generation virG-based Shigella flexneri 2a strains producing WRSf2G12 and WRSf2G15. Both strains harbor a unique combination of gene deletions designed to increase the safety of live Shigella vaccines. WRSf2G12 and WRSf2G15 are genetically stable and highly attenuated in both cell culture and animal models of infection. Ocular immunization of guinea pigs with either strain induces robust systemic and mucosal immune responses that protect against homologous challenge with wild-type Shigella. The data support further evaluation of the second-generation strains in a phase I clinical trial.
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Live attenuated Shigella dysenteriae type 1 vaccine strains overexpressing shiga toxin B subunit. Infect Immun 2011; 79:4912-22. [PMID: 21969003 DOI: 10.1128/iai.05814-11] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Shigella dysenteriae serotype 1 (S. dysenteriae 1) is unique among the Shigella species and serotypes in the expression of Shiga toxin which contributes to more severe disease sequelae and the ability to cause explosive outbreaks and pandemics. S. dysenteriae 1 shares characteristics with other Shigella species, including the capability of causing clinical illness with a very low inoculum (10 to 100 CFU) and resistance to multiple antibiotics, underscoring the need for efficacious vaccines and therapeutics. Following the demonstration of the successful attenuating capacity of deletion mutations in the guaBA operon in S. flexneri 2a vaccine strains in clinical studies, we developed a series of S. dysenteriae 1 vaccine candidates containing the fundamental attenuating mutation in guaBA. All strains are devoid of Shiga toxin activity by specific deletion of the gene encoding the StxA subunit, which encodes enzymatic activity. The StxB subunit was overexpressed in several derivatives by either plasmid-based constructs or chromosomal manipulation to include a strong promoter. All strains are attenuated for growth in vitro in the HeLa cell assay and for plaque formation and were safe in the Serény test and immunogenic in the guinea pigs. Each strain induced robust serum and mucosal anti-S. dysenteriae 1 lipopolysaccharide (LPS) responses and protected against wild-type challenge. Two strains engineered to overexpress StxB induced high titers of Shiga toxin neutralizing antibodies. These candidates demonstrate the potential for a live attenuated vaccine to protect against disease caused by S. dysenteriae 1 and potentially to protect against the toxic effects of other Shiga toxin 1-expressing pathogens.
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