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Ko W, Tseng S, Chou C, Li T, Li R, Zhang Y, Li Y, Lv Y. Molecular epidemiology and comparative genomics of carbapenemase-producing Escherichia coli isolates from 19 tertiary hospitals in China from 2019 to 2020. Front Microbiol 2023; 14:1056399. [PMID: 37152734 PMCID: PMC10160391 DOI: 10.3389/fmicb.2023.1056399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 03/23/2023] [Indexed: 05/09/2023] Open
Abstract
Background The clinical use of carbapenems is facing challenges due to increased carbapenemase-producing Escherichia coli (CP-EC) infections over the past decade. Meanwhile, whole-genome sequencing (WGS) is an important method for bacterial epidemiological research. We aim to provide more gene-based surveys to explore the genomics and occurrence of CP-EC in China. Methods A total of 780 Escherichia coli isolates were collected by the China Antimicrobial Resistance Surveillance Trial (CARST) from 2019 to 2020. An antibacterial susceptibility test was performed by using the agar dilution method. CP-EC were detected by the modified carbapenem inactivation method (mCIM), EDTA-modified carbapenem inactivation method (eCIM), and polymerase chain reaction (PCR). Homology analysis was performed by multilocus sequence typing (MLST). A conjugation experiment was performed to verify the transferability of plasmids carrying carbapenemase genes. WGS was conducted to explore the gene-environment of the carbapenemase gene. Result Of the 780 Escherichia coli isolates, 31 isolates were insensitive to carbapenem with a rate of 4%. Among them, 13 CP-EC isolates had transferability of the bla NDM gene. These isolates belonged to nine distinct sequence types (STs), with some correlation. We found that two (2/13, 15.4%) of the CP-EC isolates that were collected from blood specimens were highly pathogenic and also showed high transferability of the bla NDM gene. In addition, eight (8/13, 61.5%) of the CP-EC isolates were found to be multidrug-resistant. Conclusion With the increasing use of carbapenem, CP-EC isolates accounted for nearly half of the total carbapenem-insensitive Escherichia coli isolates. Our findings highlight the urgent need to pay attention to CP-EC isolates in bloodstream infections and ESBL-producing CP-EC isolates. Based on the One Health concept, we suggest various measures, including the development of bacterial vaccines, antibiotic management, and establishment of better medical environments, to avoid the outbreak of CP-EC.
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Affiliation(s)
- Wehsin Ko
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, China
| | - Songlu Tseng
- Department of Trauma and Orthopaedics, Peking University People's Hospital, Beijing, China
| | - Chiahsin Chou
- Department of General Surgery, Peking University First Hospital, Beijing, China
| | - Tianmeng Li
- Department of Infectious Diseases and Clinical Microbiology, Beijing Institute of Respiratory Medicine and Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Rose Li
- Department of Clinical Medicine, Civil Aviation General Hospital, Beijing, China
| | - Yaqiao Zhang
- Department of Clinical Medicine, Peking University International Hospital, Beijing, China
| | - Yun Li
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, China
- *Correspondence: Yun Li
| | - Yuan Lv
- Institute of Clinical Pharmacology, Peking University First Hospital, Beijing, China
- Yuan Lv
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Interdependence of Shigella flexneri O Antigen and Enterobacterial Common Antigen Biosynthetic Pathways. J Bacteriol 2022; 204:e0054621. [PMID: 35293778 DOI: 10.1128/jb.00546-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Outer membrane (OM) polysaccharides allow bacteria to resist harsh environmental conditions and antimicrobial agents, traffic to and persist in pathogenic niches, and evade immune responses. Shigella flexneri has two OM polysaccharide populations, being enterobacterial common antigen (ECA) and lipopolysaccharide (LPS) O antigen (Oag); both are polymerized into chains by separate homologs of the Wzy-dependent pathway. The two polysaccharide pathways, along with peptidoglycan (PG) biosynthesis, compete for the universal biosynthetic membrane anchor, undecaprenyl phosphate (Und-P), as the finite pool of available Und-P is critical in all three cell wall biosynthetic pathways. Interactions between the two OM polysaccharide pathways have been proposed in the past where, through the use of mutants in both pathways, various perturbations have been observed. Here, we show for the first time that mutations in one of the two OM polysaccharide pathways can affect each other, dependent on where the mutation lies along the pathway, while the second pathway remains genetically intact. We then expand on this and show that the mutations also affect PG biosynthesis pathways and provide data which supports that the classical mutant phenotypes of cell wall mutants are due to a lack of available Und-P. Our work here provides another layer in understanding the complex intricacies of the cell wall biosynthetic pathways and demonstrates their interdependence on Und-P, the universal biosynthetic membrane anchor. IMPORTANCE Bacterial outer membrane polysaccharides play key roles in a range of bacterial activities from homeostasis to virulence. Two such OM polysaccharide populations are ECA and LPS Oag, which are synthesized by separate homologs of the Wzy-dependent pathway. Both ECA and LPS Oag biosynthesis join with PG biosynthesis to form the cell wall biosynthetic pathways, which all are interdependent on the availability of Und-P for proper function. Our data show the direct effects of cell wall pathway mutations affecting all related pathways when they themselves remain genetically unchanged. This work furthers our understanding of the complexities and interdependence of the three cell wall pathways.
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Hermansen S, Linke D, Leo JC. Transmembrane β-barrel proteins of bacteria: From structure to function. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2022; 128:113-161. [PMID: 35034717 DOI: 10.1016/bs.apcsb.2021.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The outer membrane of Gram-negative bacteria is a specialized organelle conferring protection to the cell against various environmental stresses and resistance to many harmful compounds. The outer membrane has a number of unique features, including an asymmetric lipid bilayer, the presence of lipopolysaccharides and an individual proteome. The vast majority of the integral transmembrane proteins in the outer membrane belongs to the family of β-barrel proteins. These evolutionarily related proteins share a cylindrical, anti-parallel β-sheet core fold spanning the outer membrane. The loops and accessory domains attached to the β-barrel allow for a remarkable versatility in function for these proteins, ranging from diffusion pores and transporters to enzymes and adhesins. We summarize the current knowledge on β-barrel structure and folding and give an overview of their functions, evolution, and potential as drug targets.
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Affiliation(s)
- Simen Hermansen
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Dirk Linke
- Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway
| | - Jack C Leo
- Antimicrobial resistance, Omics and Microbiota Group, Department of Biosciences, Nottingham Trent University, Nottingham, United Kingdom.
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Kim MJ, Moon YH, Kim H, Rho S, Shin YK, Song M, Walker R, Czerkinsky C, Kim DW, Kim JO. Cross-Protective Shigella Whole-Cell Vaccine With a Truncated O-Polysaccharide Chain. Front Microbiol 2018; 9:2609. [PMID: 30429838 PMCID: PMC6220597 DOI: 10.3389/fmicb.2018.02609] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 10/12/2018] [Indexed: 11/13/2022] Open
Abstract
Shigella is a highly prevalent bacterium causing acute diarrhea and dysentery in developing countries. Shigella infections are treated with antibiotics but Shigellae are increasingly resistant to these drugs. Vaccination can be a countermeasure against emerging antibiotic-resistant shigellosis. Because of the structural variability in Shigellae O-antigen polysaccharides (Oag), cross-protective Shigella vaccines cannot be derived from single serotype-specific Oag. We created an attenuated Shigella flexneri 2a strain with one rather than multiple Oag units by disrupting the Oag polymerase gene (Δwzy), which broadened protective immunogenicity by exposing conserved surface proteins. Inactivated Δwzy mutant cells combined with Escherichia coli double mutant LT(R192G/L211A) as adjuvant, induced potent antibody responses to outer membrane protein PSSP-1, and type III secretion system proteins IpaB and IpaC. Intranasal immunization with the vaccine preparation elicited cross-protective immunity against S. flexneri 2a, S. flexneri 3a, S. flexneri 6, and Shigella sonnei in a mouse pneumonia model. Thus, S. flexneri 2a Δwzy represents a promising candidate strain for a universal Shigella vaccine.
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Affiliation(s)
- Min Jung Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea.,Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Young-Hye Moon
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Heejoo Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Semi Rho
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Young Kee Shin
- Laboratory of Molecular Pathology and Cancer Genomics, College of Pharmacy, Seoul National University, Seoul, South Korea
| | - Manki Song
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | | | - Cecil Czerkinsky
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea.,Institut de Pharmacologie Moléculaire & Cellulaire CNRS-INSERM-University of Nice Sophia Antipolis, Valbonne, France
| | - Dong Wook Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
| | - Jae-Ouk Kim
- Clinical Research Lab, International Vaccine Institute, Seoul National University Research Park, Seoul, South Korea
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Standish AJ, Teh MY, Tran ENH, Doyle MT, Baker PJ, Morona R. Unprecedented Abundance of Protein Tyrosine Phosphorylation Modulates Shigella flexneri Virulence. J Mol Biol 2016; 428:4197-4208. [PMID: 27380737 DOI: 10.1016/j.jmb.2016.06.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/06/2016] [Accepted: 06/23/2016] [Indexed: 01/09/2023]
Abstract
Evidence is accumulating that protein tyrosine phosphorylation plays a crucial role in the ability of important human bacterial pathogens to cause disease. While most works have concentrated on its role in the regulation of a major bacterial virulence factor, the polysaccharide capsule, recent studies have suggested a much broader role for this post-translational modification. This prompted us to investigate protein tyrosine phosphorylation in the human pathogen Shigella flexneri. We first completed a tyrosine phosphoproteome, identifying 905 unique tyrosine phosphorylation sites on at least 573 proteins (approximately 15% of all proteins). This is the most tyrosine-phosphorylated sites and proteins in a single bacterium identified to date, substantially more than the level seen in eukaryotic cells. Most had not previously been identified and included proteins encoded by the virulence plasmid, which is essential for S. flexneri to invade cells and cause disease. In order to investigate the function of these phosphorylation sites in important virulence factors, phosphomimetic and ablative mutations were constructed in the type 3 secretion system ATPase Spa47 and the master virulence regulator VirB. This revealed that tyrosine residues phosphorylated in our study are critical for Spa47 and VirB activity, and tyrosine phosphorylation likely regulates their functional activity and subsequently the virulence of this major human pathogen. This study suggests that tyrosine phosphorylation plays a critical role in regulating a wide variety of virulence factors in the human pathogen S. flexneri and serves as a base for future studies defining its complete role.
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Affiliation(s)
- Alistair James Standish
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia.
| | - Min Yan Teh
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Elizabeth Ngoc Hoa Tran
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Matthew Thomas Doyle
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Paul J Baker
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
| | - Renato Morona
- Research Centre for Infectious Diseases, Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, South Australia 5005, Australia
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Holtappels M, Noben JP, Valcke R. Virulence of Erwinia amylovora, a prevalent apple pathogen: Outer membrane proteins and type III secreted effectors increase fitness and compromise plant defenses. Proteomics 2016; 16:2377-90. [PMID: 27345300 DOI: 10.1002/pmic.201500513] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 01/30/2023]
Abstract
Until now, no data are available on the outer membrane (OM) proteome of Erwinia amylovora, a Gram-negative plant pathogen, causing fire blight in most of the members of the Rosaceae family. Since the OM forms the interface between the bacterial cell and its environment it is in direct contact with the host. Additionally, the type III secretion system, embedded in the OM, is a pathogenicity factor of E. amylovora. To assess the influence of the OM composition and the secretion behavior on virulence, a 2D-DIGE analysis and gene expression profiling were performed on a high and lower virulent strain, both in vitro and in planta. Proteome data showed an increase in flagellin for the lower virulent strain in vitro, whereas, in planta several interesting proteins were identified as being differently expressed between both the strains. Further, gene expression of nearly all type III secreted effectors was elevated for the higher virulent strain, both in vitro and in planta. As a first, we report that several characteristics of virulence can be assigned to the OM proteome. Moreover, we demonstrate that secreted proteins prove to be the important factors determining differences in virulence between the strains, otherwise regarded as homogeneous on a genome level.
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Affiliation(s)
- Michelle Holtappels
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium
| | - Jean-Paul Noben
- School of Life Sciences, Biomedical Research Institute, Hasselt University and Transnational University Limburg, Hasselt, Belgium
| | - Roland Valcke
- Molecular and Physical Plant Physiology, Faculty of Sciences, Hasselt University, Diepenbeek, Belgium.
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Doyle MT, Grabowicz M, Morona R. A small conserved motif supports polarity augmentation of Shigella flexneri IcsA. MICROBIOLOGY-SGM 2015; 161:2087-97. [PMID: 26315462 DOI: 10.1099/mic.0.000165] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The rod-shaped enteric intracellular pathogen Shigella flexneri and other Shigella species are the causative agents of bacillary dysentery. S. flexneri are able to spread within the epithelial lining of the gut, resulting in lesion formation, cramps and bloody stools. The outer membrane protein IcsA is essential for this spreading process. IcsA is the initiator of an actin-based form of motility whereby it allows the formation of a filamentous actin 'tail' at the bacterial pole. Importantly, IcsA is specifically positioned at the bacterial pole such that this process occurs asymmetrically. The mechanism of IcsA polarity is not completely understood, but it appears to be a multifactorial process involving factors intrinsic to IcsA and other regulating factors. In this study, we further investigated IcsA polarization by its intramolecular N-terminal and central polar-targeting (PT) regions (nPT and cPT regions, respectively). The results obtained support a role in polar localization for the cPT region and contend the role of the nPT region. We identified single IcsA residues that have measurable impacts on IcsA polarity augmentation, resulting in decreased S. flexneri sprading efficiency. Intriguingly, regions and residues involved in PT clustered around a highly conserved motif which may provide a functional scaffold for polarity-augmenting residues. How these results fit with the current model of IcsA polarity determination is discussed.
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Affiliation(s)
- Matthew Thomas Doyle
- 1Department of Molecular and Cellular Biology, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
| | - Marcin Grabowicz
- 2Department of Molecular Biology, Princeton University, Princeton, NJ 08544-1014, USA
| | - Renato Morona
- 1Department of Molecular and Cellular Biology, School of Biological Sciences, The University of Adelaide, Adelaide, SA 5005, Australia
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8
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Tran ENH, Attridge SR, Teh MY, Morona R. Shigella flexneri cell-to-cell spread, and growth and inflammation in mice, is limited by the outer membrane protease IcsP. FEMS Microbiol Lett 2015; 362:fnv088. [PMID: 26025071 DOI: 10.1093/femsle/fnv088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2015] [Indexed: 12/20/2022] Open
Abstract
The Shigella flexneri autotransporter protein IcsA is essential for intra- and intercellular spread, and icsA mutants are attenuated in several models. However, the pathogenic significance of the outer membrane protease IcsP, which orchestrates the polar distribution of IcsA on the bacterial surface, remains unclear. To further examine this point, we constructed icsP mutants in the two most commonly studied S. flexneri strains and evaluated their in vitro and in vivo performance relative to wild type. Both icsP mutants showed aberrant surface distribution of IcsA, but the in vitro consequences depended upon the cell line being used to assess bacterial motility and plaque formation. Evaluating the behaviour of the mutants in two mouse models suggested functional expression of icsP might limit bacterial persistence and the associated inflammation in host tissues, consistent with the findings in one of the three cell lines used.
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Affiliation(s)
- Elizabeth Ngoc Hoa Tran
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Stephen R Attridge
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Min Yan Teh
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
| | - Renato Morona
- Department of Molecular and Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, SA 5005, Australia
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Doyle MT, Tran ENH, Morona R. The passenger-associated transport repeat promotes virulence factor secretion efficiency and delineates a distinct autotransporter subtype. Mol Microbiol 2015; 97:315-29. [PMID: 25869731 DOI: 10.1111/mmi.13027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/10/2015] [Indexed: 11/28/2022]
Abstract
Autotransporters are a superfamily of virulence factors secreted by Gram negative bacteria. They are comprised of an N-terminal passenger domain that is translocated across the outer membrane and a C-terminal domain that inserts into the outer membrane forming a β-barrel anchor. It is still poorly understood how the passenger is efficiently translocated in the absence of external energy inputs. Several mechanisms have been proposed in solution of this problem, yet due to the vast diversity of size, sequence and function of the passenger, it is not clear how widely these mechanisms are employed. In this study we functionally characterize a conserved repeat found in many passengers that we designate the Passenger-associated Transport Repeat (PATR). Using the autotransporter IcsA from the enteropathogen Shigella flexneri, we identified conserved PATR residues that are required for efficient export of the passenger during growth and infection. Furthermore, PATR-containing autotransporters are significantly larger than non-PATR autotransporters, with PATR copy number correlating with passenger size. We also show that PATR-containing autotransporters delineate a subgroup that associates with specific virulence traits and architectures. These results advance our understanding of autotransporter composition and indicate that an additional transport mechanism is important for thousands of these proteins.
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Affiliation(s)
- Matthew Thomas Doyle
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Elizabeth Ngoc Hoa Tran
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
| | - Renato Morona
- Department of Molecular and Cellular Biology, School of Biological Sciences, Discipline of Microbiology and Immunology, School of Molecular and Biomedical Science, University of Adelaide, Adelaide, South Australia, 5005, Australia
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Doyle MT, Grabowicz M, May KL, Morona R. Lipopolysaccharide surface structure does not influence IcsA polarity. FEMS Microbiol Lett 2015; 362:fnv042. [DOI: 10.1093/femsle/fnv042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/11/2015] [Indexed: 12/26/2022] Open
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Shigella outer membrane protein PSSP-1 is broadly protective against Shigella infection. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2015; 22:381-8. [PMID: 25651919 DOI: 10.1128/cvi.00661-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In developing countries, Shigella is a primary cause of diarrhea in infants and young children. Although antibiotic therapy is an effective treatment for shigellosis, therapeutic options are narrowing due to the emergence of antibiotic resistance. Thus, preventive vaccination could become the most efficacious approach for controlling shigellosis. We have identified several conserved protein antigens that are shared by multiple Shigella serotypes and species. Among these, one antigen induced cross-protection against experimental shigellosis, and we have named it pan-Shigella surface protein 1 (PSSP-1). PSSP-1-induced protection requires a mucosal administration route and coadministration of an adjuvant. When PSSP-1 was administered intranasally, it induced cross-protection against Shigella flexneri serotypes 2a, 5a, and 6, Shigella boydii, Shigella sonnei, and Shigella dysenteriae serotype 1. Intradermally administered PSSP-1 induced strong serum antibody responses but failed to induce protection in the mouse lung pneumonia model. In contrast, intranasal administration elicited efficient local and systemic antibody responses and production of interleukin 17A and gamma interferon. Interestingly, blood samples from patients with recent-onset shigellosis showed variable but significant mucosal antibody responses to other conserved Shigella protein antigens but not to PSSP-1. We suggest that PSSP-1 is a promising antigen for a broadly protective vaccine against Shigella.
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Brotcke Zumsteg A, Goosmann C, Brinkmann V, Morona R, Zychlinsky A. IcsA is a Shigella flexneri adhesin regulated by the type III secretion system and required for pathogenesis. Cell Host Microbe 2015; 15:435-45. [PMID: 24721572 DOI: 10.1016/j.chom.2014.03.001] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 01/20/2014] [Accepted: 02/24/2014] [Indexed: 01/05/2023]
Abstract
Following contact with the epithelium, the enteric intracellular bacterial pathogen Shigella flexneri invades epithelial cells and escapes intracellular phagosomal destruction using its type III secretion system (T3SS). The bacterium replicates within the host cell cytosol and spreads between cells using actin-based motility, which is mediated by the virulence factor IcsA (VirG). Whereas S. flexneri invasion is well characterized, adhesion mechanisms of the bacterium remain elusive. We found that IcsA also functions as an adhesin that is both necessary and sufficient to promote contact with host cells. As adhesion can be beneficial or deleterious depending on the host cell type, S. flexneri regulates IcsA-dependent adhesion. Activation of the T3SS in response to the bile salt deoxycholate triggers IcsA-dependent adhesion and enhances pathogen invasion. IcsA-dependent adhesion contributes to virulence in a mouse model of shigellosis, underscoring the importance of this adhesin to S. flexneri pathogenesis.
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Affiliation(s)
- Anna Brotcke Zumsteg
- Department of Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin 13353, Germany
| | - Christian Goosmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology, Berlin 13353, Germany
| | - Volker Brinkmann
- Microscopy Core Facility, Max Planck Institute for Infection Biology, Berlin 13353, Germany
| | - Renato Morona
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide 5000, South Australia, Australia
| | - Arturo Zychlinsky
- Department of Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin 13353, Germany.
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Abstract
PURPOSE OF REVIEW Shigella spp. are important etiologic agents of diarrhea worldwide. This review summarizes the recent findings on the epidemiology, diagnosis, virulence genes, and pathobiology of Shigella infection. RECENT FINDINGS Shigella flexneri and Shigella sonnei have been identified as the main serogroups circulating in developing and developed countries, respectively. However, a shift in the dominant species from S. flexneri to S. sonnei has been observed in countries that have experienced recent improvements in socioeconomic conditions. Despite the increasing usage of molecular methods in the diagnosis and virulence characterization of Shigella strains, researchers have been unsuccessful in finding a specific target gene for this bacillus. New research has demonstrated the role of proteins whose expressions are temperature-regulated, as well as genes involved in the processes of adhesion, invasion, dissemination, and inflammation, aiding in the clarification of the complex pathobiology of shigellosis. SUMMARY Knowledge about the epidemiologic profile of circulating serogroups of Shigella and an understanding of its pathobiology as well as of the virulence genes is important for the development of preventive measures and interventions to reduce the worldwide spread of shigellosis.
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Localization of the outer membrane protein OmpA2 in Caulobacter crescentus depends on the position of the gene in the chromosome. J Bacteriol 2014; 196:2889-900. [PMID: 24891444 DOI: 10.1128/jb.01516-14] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outer membrane of Gram-negative bacteria is an essential structure involved in nutrient uptake, protection against harmful substances, and cell growth. Different proteins keep the outer membrane from blebbing out by simultaneously interacting with it and with the cell wall. These proteins have been mainly studied in enterobacteria, where OmpA and the Braun and Pal lipoproteins stabilize the outer membrane. Some degree of functional redundancy exists between these proteins, since none of them is essential but the absence of two of them results in a severe phenotype. Caulobacter crescentus has a different strategy to maintain its outer membrane, since it lacks the Braun lipoprotein and Pal is essential. In this work, we characterized OmpA2, an OmpA-like protein, in this bacterium. Our results showed that this protein is required for normal stalk growth and that it plays a minor role in the stability of the outer membrane. An OmpA2 fluorescent fusion protein showed that the concentration of this protein decreases from the stalk to the new pole. This localization pattern is important for its function, and it depends on the position of the gene locus in the chromosome and, as a consequence, in the cell. This result suggests that little diffusion occurs from the moment that the gene is transcribed until the mature protein attaches to the cell wall in the periplasm. This mechanism reveals the integration of different levels of information from protein function down to genome arrangement that allows the cell to self-organize.
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