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Zhang Y, Hao S, Xiao N, Zhang Y, Wang H, Li L, Fu R, Shao Z. Ferritin Light Chain: A Candidate Autoantigen in Immuno-Related Pancytopenia. Front Immunol 2022; 13:851096. [PMID: 35572557 PMCID: PMC9097271 DOI: 10.3389/fimmu.2022.851096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Accepted: 03/29/2022] [Indexed: 11/19/2022] Open
Abstract
The characteristic feature of immune-related pancytopenia (IRP) is autoantibody-mediated bone marrow (BM) damage and peripheral blood cytopenia. We found that the potential antigen of IRP was Ferritin light chain (FTL) by SEREX (serological analysis of recombinant cDNA expression libraries) in the previous study. In this study, we tried to explore the antigenic epitopes of FTL and verify its antigenicity in IRP. We found the possible FTL epitope: VNLYLQASYTYLSLG by phage random peptide library. Through ELISPOT, it was found that peptide VNLYLQASYTYLSLG can significantly stimulate the production of interleukin-4 and cannot stimulate the production of interferon-γ, which suggested that the peptide can obviously activate Th2 cells. Peptide-major histocompatibility complex tetramer elicited antigen-specific T cell responses. The expression levels of FTL were significantly increased in the patients with untreated IRP (P < 0.05). In conclusion, we found that FTL is the target antigen for some patients with IRP. The peptide of VNLYLQASYTYLSLG is an epitope of the target antigen. The target antigen is abnormally overexpressed on the membrane of BM cells, especially on the surface of CD34+ BM cells of patients with IRP. In addition, it is related to the severity of disease. These results provide a possible new target for the treatment of IRP in the future.
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Affiliation(s)
| | | | | | | | | | | | | | - Zonghong Shao
- Department of Hematology, Tianjin Medical University General Hospital, Tianjin, China
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Cesinger MR, Schwardt NH, Halsey CR, Thomason MK, Reniere ML. Investigating the Roles of Listeria monocytogenes Peroxidases in Growth and Virulence. Microbiol Spectr 2021; 9:e0044021. [PMID: 34287055 PMCID: PMC8552690 DOI: 10.1128/spectrum.00440-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 06/23/2021] [Indexed: 11/25/2022] Open
Abstract
Bacteria have necessarily evolved a protective arsenal of proteins to contend with peroxides and other reactive oxygen species generated in aerobic environments. Listeria monocytogenes encounters an onslaught of peroxide both in the environment and during infection of the mammalian host, where it is the causative agent of the foodborne illness listeriosis. Despite the importance of peroxide for the immune response to bacterial infection, the strategy by which L. monocytogenes protects against peroxide toxicity has yet to be illuminated. Here, we investigated the expression and essentiality of all the peroxidase-encoding genes during L. monocytogenes growth in vitro and during infection of murine cells in tissue culture. We found that chdC and kat were required for aerobic growth in vitro, and fri and ahpA were each required for L. monocytogenes to survive acute peroxide stress. Despite increased expression of fri, ahpA, and kat during infection of macrophages, only fri proved necessary for cytosolic growth. In contrast, the proteins encoded by lmo0367, lmo0983, tpx, lmo1609, and ohrA were dispensable for aerobic growth, acute peroxide detoxification, and infection. Together, our results provide insight into the multifaceted L. monocytogenes peroxide detoxification strategy and demonstrate that L. monocytogenes encodes a functionally diverse set of peroxidase enzymes. IMPORTANCE Listeria monocytogenes is a facultative intracellular pathogen and the causative agent of the foodborne illness listeriosis. L. monocytogenes must contend with reactive oxygen species generated extracellularly during aerobic growth and intracellularly by the host immune system. However, the mechanisms by which L. monocytogenes defends against peroxide toxicity have not yet been defined. Here, we investigated the roles of each of the peroxidase-encoding genes in L. monocytogenes growth, peroxide stress response, and virulence in mammalian cells.
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Affiliation(s)
- Monica R. Cesinger
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Nicole H. Schwardt
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Cortney R. Halsey
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Maureen K. Thomason
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
| | - Michelle L. Reniere
- Department of Microbiology, University of Washington School of Medicine, Seattle, Washington, USA
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Jarvis NA, O'Bryan CA, Ricke SC, Johnson MG, Crandall PG. A review of minimal and defined media for growth of Listeria monocytogenes. Food Control 2016. [DOI: 10.1016/j.foodcont.2016.02.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Lechowicz J, Krawczyk-Balska A. An update on the transport and metabolism of iron in Listeria monocytogenes: the role of proteins involved in pathogenicity. Biometals 2015; 28:587-603. [PMID: 25820385 PMCID: PMC4481299 DOI: 10.1007/s10534-015-9849-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Accepted: 03/17/2015] [Indexed: 12/21/2022]
Abstract
Listeria monocytogenes is a Gram-positive bacterium that causes a rare but severe human disease with high mortality rate. The microorganism is widespread in the natural environment where it shows a saprophytic lifestyle. In the human body it infects many different cell types, where it lives intracellularly, however it may also temporarily live extracellularly. The ability to survive and grow in such diverse niches suggests that this bacterium has a wide range of mechanisms for both the acquisition of various sources of iron and effective management of this microelement. In this review, data about the mechanisms of transport, metabolism and regulation of iron, including recent findings in these areas, are summarized with focus on the importance of these mechanisms for the virulence of L. monocytogenes. These data indicate the key role of haem transport and maintenance of intracellular iron homeostasis for the pathogenesis of L. monocytogenes. Furthermore, some of the proteins involved in iron homeostasis like Fri and FrvA seem to deserve special attention due to their potential use in the development of new therapeutic antilisterial strategies.
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Affiliation(s)
- Justyna Lechowicz
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096, Warsaw, Poland
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Krawczyk-Balska A, Lipiak M. Critical role of a ferritin-like protein in the control of Listeria monocytogenes cell envelope structure and stability under β-lactam pressure. PLoS One 2013; 8:e77808. [PMID: 24204978 PMCID: PMC3812014 DOI: 10.1371/journal.pone.0077808] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 09/05/2013] [Indexed: 02/08/2023] Open
Abstract
The human pathogen Listeria monocytogenes is susceptible to the β-lactam antibiotics penicillin G and ampicillin, and these are the drugs of choice for the treatment of listerial infections. However, these antibiotics exert only a bacteriostatic effect on this bacterium and consequently, L. monocytogenes is regarded as β-lactam tolerant. It is widely accepted that the phenomenon of bacterial tolerance to β-lactams is due to the lack of adequate autolysin activity, but the mechanisms of L. monocytogenes tolerance to this class of antibiotics are poorly characterized. A ferritin-like protein (Fri) was recently identified as a mediator of β-lactam tolerance in L. monocytogenes, but its function in this process remains unknown. The present study was undertaken to improve our understanding of L. monocytogenes tolerance to β-lactams and to characterize the role of Fri in this phenomenon. A comparative physiological analysis of wild-type L. monocytogenes and a fri deletion mutant provided evidence of a multilevel mechanism controlling autolysin activity in cells grown under β-lactam pressure, which leads to a reduction in the level and/or activity of cell wall-associated autolysins. This is accompanied by increases in the amount of teichoic acids, cell wall thickness and cell envelope integrity of L. monocytogenes grown in the presence of penicillin G, and provides the basis for the innate β-lactam tolerance of this bacterium. Furthermore, this study revealed the inability of the L. monocytogenes Δ fri mutant to deplete autolysins from the cell wall, to adjust the content of teichoic acids and to maintain their D-alanylation at the correct level when treated with penicillin G, thus providing further evidence that Fri is involved in the control of L. monocytogenes cell envelope structure and stability under β-lactam pressure.
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Affiliation(s)
- Agata Krawczyk-Balska
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Magdalena Lipiak
- Department of Applied Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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Age-dependent differences in systemic and cell-autonomous immunity to L. monocytogenes. Clin Dev Immunol 2013; 2013:917198. [PMID: 23653659 PMCID: PMC3638699 DOI: 10.1155/2013/917198] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2013] [Accepted: 03/07/2013] [Indexed: 12/13/2022]
Abstract
Host defense against infection can broadly be categorized into systemic immunity and cell-autonomous immunity. Systemic immunity is crucial for all multicellular organisms, increasing in importance with increasing cellular complexity of the host. The systemic immune response to Listeria monocytogenes has been studied extensively in murine models; however, the clinical applicability of these findings to the human newborn remains incompletely understood. Furthermore, the ability to control infection at the level of an individual cell, known as “cell-autonomous immunity,” appears most relevant following infection with L. monocytogenes; as the main target, the monocyte is centrally important to innate as well as adaptive systemic immunity to listeriosis. We thus suggest that the overall increased risk to suffer and die from L. monocytogenes infection in the newborn period is a direct consequence of age-dependent differences in cell-autonomous immunity of the monocyte to L. monocytogenes. We here review what is known about age-dependent differences in systemic innate and adaptive as well as cell-autonomous immunity to infection with Listeria monocytogenes.
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Zheng WJ, Hu YH, Sun L. The two Dps of Edwardsiella tarda are involved in resistance against oxidative stress and host infection. FISH & SHELLFISH IMMUNOLOGY 2011; 31:985-992. [PMID: 21907291 DOI: 10.1016/j.fsi.2011.08.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 08/03/2011] [Accepted: 08/20/2011] [Indexed: 05/31/2023]
Abstract
DNA-binding protein from starved cells (Dps) is a member of ferritin-like proteins that exhibit properties of nonspecific DNA binding and iron oxidation and storage. Although studies of Dps from many bacterial species have been reported, no investigations on Dps from fish pathogens have been documented. In this study, we examined the biological function of two Dps proteins, Dps1 and Dps2, from Edwardsiella tarda, an important fish bacterial pathogen that can also infect humans. Dps1 and Dps2 are, respectively, 163- and 174-residue in length and each contains the conserved ferroxidase center of Dps. Expression of dps1 and dps2 was growth phase-dependent and reached high levels in stationary phase. Purified recombinant Dps1 and Dps2 were able to mediate iron oxidation by H(2)O(2) and bind DNA. Compared to the wild type strain, (i) the dps1 mutant (TXDps1) and the dps2 mutant (TXDps2) were unaffected in growth, while the dps2 mutant with interfered dps1 expression (TXDps2RI) exhibited a prolonged lag phase; (ii) TXDps1, TXDps2, and especially TXDps2RI were significantly reduced in H(2)O(2) and UV tolerance and impaired in the capacity to invade into host tissues and replicate in head kidney macrophages; (iii) TXDps1, TXDps2, and TXDps2RI induced stronger macrophage respiratory burst activity and thus were defective in the ability to block the bactericidal response of macrophages. Taken together, these results indicate that Dps1 and Dps2 are functional analogues that possess ferroxidase activity and DNA binding capacity and are required for optimum oxidative stress resistance and full bacterial virulence.
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Affiliation(s)
- Wen-jiang Zheng
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, 7 Nanhai Road, Qingdao 266071, PR China
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The impact of iron on Listeria monocytogenes; inside and outside the host. Curr Opin Biotechnol 2011; 22:194-9. [DOI: 10.1016/j.copbio.2010.10.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 10/01/2010] [Accepted: 10/05/2010] [Indexed: 11/19/2022]
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Mohamed W, Sethi S, Darji A, Mraheil MA, Hain T, Chakraborty T. Antibody targeting the ferritin-like protein controls Listeria infection. Infect Immun 2010; 78:3306-14. [PMID: 20439472 PMCID: PMC2897390 DOI: 10.1128/iai.00210-10] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 04/02/2010] [Accepted: 04/25/2010] [Indexed: 11/20/2022] Open
Abstract
The acquisition of iron during the infection process is essential for the growth of pathogenic microorganisms (S. C. Andrews, Adv. Microb. Physiol. 40:281-351, 1998; H. M. Baker, B. F. Anderson, and E. N. Baker, Proc. Natl. Acad. Sci. U. S. A. 100:3579-3583, 2003). Since the solubility of iron is low and it is toxic at low concentrations, following uptake, iron is stored in subcellular microenvironments in the iron storage protein ferritin (C. Cheers and M. Ho, J. Reticuloendothel. Soc. 34:299-309, 1983). Here, we show that ferritin-like proteins (Frl) are highly conserved in the genus Listeria and demonstrate that these proteins are present in both the cytoplasm and cell wall fractions of these bacteria. Even though Frl is expressed under different growth conditions, transcriptional mapping revealed that its regulation is complex. When bacteria are grown in brain heart infusion medium, extracellular expression involves both sigma A (SigA)- and sigma B (SigB)-dependent promoters; however, during intracellular growth, initiation of transcription is additionally SigB dependent. The expression of Frl is greatly enhanced in bacteria grown in the presence of blood, and a mutant strain lacking the frl gene was defective for growth in this medium. Using the monoclonal antibody (MAb) specific for Frl, we demonstrate that administration of anti-Frl MAb prior to infection confers antilisterial resistance in vivo, evidenced in reduced bacterial load and increased survival rates, thereby demonstrating the in vivo significance of upregulated cell surface-associated Frl expression. In vitro studies revealed that the antilisterial resistance is due to increased listerial phagocytosis.
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Affiliation(s)
- Walid Mohamed
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Shneh Sethi
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Ayub Darji
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Mobarak A. Mraheil
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Torsten Hain
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Trinad Chakraborty
- Institute for Medical Microbiology, Justus-Liebig-University, Frankfurter Str. 107, D-35392 Giessen, Germany, Centre de Recerca en Sanitat Animal, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
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Camejo A, Buchrieser C, Couvé E, Carvalho F, Reis O, Ferreira P, Sousa S, Cossart P, Cabanes D. In vivo transcriptional profiling of Listeria monocytogenes and mutagenesis identify new virulence factors involved in infection. PLoS Pathog 2009; 5:e1000449. [PMID: 19478867 PMCID: PMC2679221 DOI: 10.1371/journal.ppat.1000449] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Accepted: 04/27/2009] [Indexed: 11/18/2022] Open
Abstract
Listeria monocytogenes is a human intracellular pathogen able to colonize host tissues after ingestion of contaminated food, causing severe invasive infections. In order to gain a better understanding of the nature of host-pathogen interactions, we studied the L. monocytogenes genome expression during mouse infection. In the spleen of infected mice, approximately 20% of the Listeria genome is differentially expressed, essentially through gene activation, as compared to exponential growth in rich broth medium. Data presented here show that, during infection, Listeria is in an active multiplication phase, as revealed by the high expression of genes involved in replication, cell division and multiplication. In vivo bacterial growth requires increased expression of genes involved in adaptation of the bacterial metabolism and stress responses, in particular to oxidative stress. Listeria interaction with its host induces cell wall metabolism and surface expression of virulence factors. During infection, L. monocytogenes also activates subversion mechanisms of host defenses, including resistance to cationic peptides, peptidoglycan modifications and release of muramyl peptides. We show that the in vivo differential expression of the Listeria genome is coordinated by a complex regulatory network, with a central role for the PrfA-SigB interplay. In particular, L. monocytogenes up regulates in vivo the two major virulence regulators, PrfA and VirR, and their downstream effectors. Mutagenesis of in vivo induced genes allowed the identification of novel L. monocytogenes virulence factors, including an LPXTG surface protein, suggesting a role for S-layer glycoproteins and for cadmium efflux system in Listeria virulence.
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Affiliation(s)
- Ana Camejo
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
| | - Carmen Buchrieser
- Institut Pasteur, UP Biologie des Bactéries Intracellulaires and CNRS URA 2171, Paris, France
| | - Elisabeth Couvé
- Institut Pasteur, Unité Génétique des Génomes Bactériens CNRS URA 2171, Paris, France
| | - Filipe Carvalho
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
| | - Olga Reis
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
| | - Pierre Ferreira
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
| | - Sandra Sousa
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
| | - Pascale Cossart
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Paris, France
- Inserm U604, Paris, France
- INRA USC2020, Paris, France
| | - Didier Cabanes
- IBMC - Instituto de Biologia Molecular e Celular, Group of Molecular Microbiology, Universidade do Porto, Porto, Portugal
- * E-mail:
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Fiorini F, Stefanini S, Valenti P, Chiancone E, De Biase D. Transcription of the Listeria monocytogenes fri gene is growth-phase dependent and is repressed directly by Fur, the ferric uptake regulator. Gene 2008; 410:113-21. [PMID: 18222616 DOI: 10.1016/j.gene.2007.12.007] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2007] [Revised: 11/23/2007] [Accepted: 12/03/2007] [Indexed: 11/26/2022]
Abstract
The Listeria monocytogenes fri gene encodes the only ferritin-like protein of this pathogen, a Dps protein (DNA binding protein from starved cells). Listeria Dps is endowed with the capacity to detoxify concurrently free iron and H(2)O(2), is essential for virulence and is required for efficient bacterial growth at early stages of the infection process. The transcription of fri is known to depend on sigma(A) and sigma(B) factors, to be affected by growth conditions and to be derepressed in a perR (peroxide-inducible stress response regulator) mutant background. The present work shows that fri transcription is restricted to the exponential phase of growth, whereas the Dps protein has a long half-life and is detected in significant amounts also in stationary phase cells. Expression of fri is downregulated under iron-rich conditions and is controlled directly by Fur, the ferric uptake regulator, which binds within the DNA region encompassing nucleotides from position -23 to position +90 relative to the proximal sigma(A) transcription startpoint. The putative Fur-box is proposed to coincide with the putative Per-box both in sequence and position. The primary structure of L. monocytogenes Fur has a high degree of similarity with homologues of known X-ray crystal structure. The molecular model of L. monocytogenes Fur built on this basis shows that the ligands of the structural Zn(II) and of the regulatory Fe(II) are conserved and are located in positions fully compatible with their respective roles.
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Affiliation(s)
- Francesca Fiorini
- Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università La Sapienza, Rome, Italy
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Dussurget O. Chapter 1 New Insights into Determinants of Listeria Monocytogenes Virulence. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2008; 270:1-38. [DOI: 10.1016/s1937-6448(08)01401-9] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Liu D, Lawrence ML, Ainsworth AJ, Austin FW. Toward an improved laboratory definition of Listeria monocytogenes virulence. Int J Food Microbiol 2007; 118:101-15. [PMID: 17727992 DOI: 10.1016/j.ijfoodmicro.2007.07.045] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2006] [Revised: 04/07/2007] [Accepted: 07/28/2007] [Indexed: 11/23/2022]
Abstract
Listeria monocytogenes is an opportunistic foodborne pathogen that encompasses a diversity of strains with varied virulence. The ability to rapidly determine the pathogenic potential of L. monocytogenes strains is integral to the control and prevention campaign against listeriosis. Early methods for assessing L. monocytogenes virulence include in vivo bioassays and in vitro cell assays. While in vivo bioassays provide a measurement of all virulence determinants of L. monocytogenes, they are not applied routinely due to their reliance on experimental animals whose costs have become increasingly prohibitive. As a low cost alternative, in vitro cell assays are useful for estimating the virulence of L. monocytogenes strains. However, these assays are often slow, and at times variable. Prior attempts to ascertain L. monocytogenes virulence by targeting virulence-associated proteins and genes have been largely unsuccessful, since many of the assay targets are present in both virulent and avirulent strains. Recent identification of novel virulence-specific genes (particularly internalin gene inlJ) has opened a new avenue for rapid, sensitive, and precise differentiation of virulent L. monocytogenes strains from avirulent strains. The application of DNA sequencing technique also offers an additional tool for assessing L. monocytogenes virulence potential. By providing an update on the laboratory methods that have been reported for the determination of L. monocytogenes pathogenicity, this review discusses future research needs that may help achieve an improved laboratory definition of L. monocytogenes virulence.
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Affiliation(s)
- Dongyou Liu
- College of Veterinary Medicine, Mississippi State University, PO Box 6100, Mississippi State, MS 39762, USA.
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