scholarly journals Phloretin Attenuates Listeria monocytogenes Virulence Both In vitro and In vivo by Simultaneously Targeting Listeriolysin O and Sortase A

2017 ◽  
Vol 7 ◽  
Author(s):  
Jianfeng Wang ◽  
Bowen Liu ◽  
Zihao Teng ◽  
Xuan Zhou ◽  
Xiyan Wang ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sortase A ◽  
Listeriolysin O

scholarly journals Morin inhibits Listeria monocytogenes virulence in vivo and in vitro by targeting listeriolysin O and inflammation

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Gen Li ◽  
Guizhen Wang ◽  
Meng Li ◽  
Li Li ◽  
Hongtao Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Listeriolysin O

scholarly journals Recombinant Listeria monocytogenes Expressing a Cell Wall-Associated Listeriolysin O Is Weakly Virulent but Immunogenic

2009 ◽  
Vol 77 (10) ◽  
pp. 4371-4382 ◽  
Author(s):  
Javier A. Carrero ◽  
Boris Calderon ◽  
Hector Vivanco-Cid ◽  
Emil R. Unanue
Keyword(s):  
Listeria Monocytogenes ◽  
Listeriolysin O ◽  
Wild Type ◽  
Positive Bacterium ◽  
Cell Responses ◽  
A Cell ◽  
Weakly Virulent

ABSTRACT Listeriolysin O (LLO) is an essential virulence factor for the gram-positive bacterium Listeria monocytogenes. Our goal was to determine if altering the topology of LLO would alter the virulence and toxicity of L. monocytogenes in vivo. A recombinant strain was generated that expressed a surface-associated LLO (sLLO) variant secreted at 40-fold-lower levels than the wild type. In culture, the sLLO strain grew in macrophages, translocated to the cytosol, and induced cell death. However, the sLLO strain showed decreased infectivity, reduced lymphocyte apoptosis, and decreased virulence despite a normal in vitro phenotype. Thus, the topology of LLO in L. monocytogenes was a factor in the pathogenesis of the infection and points to a role of LLO secretion during in vivo infection. The sLLO strain was cleared by severe combined immunodeficient (SCID) mice. Despite the attenuation of virulence, the sLLO strain was immunogenic and capable of eliciting protective T-cell responses.

scholarly journals Development of a Single-Gene, Signature-Tag-Based Approach in Combination with Alanine Mutagenesis To Identify Listeriolysin O Residues Critical for theIn VivoSurvival of Listeria monocytogenes

2012 ◽  
Vol 80 (6) ◽  
pp. 2221-2230 ◽  
Author(s):  
Jody A. Melton-Witt ◽  
Susannah L. McKay ◽  
Daniel A. Portnoy
Keyword(s):  
Listeria Monocytogenes ◽  
Single Gene ◽  
Saturation Mutagenesis ◽  
Single Amino Acid ◽  
Screening Methods ◽  
Listeriolysin O ◽  
Phenotypic Analysis ◽  
Content Type

ABSTRACTListeriolysin O (LLO) is a pore-forming toxin of the cholesterol-dependent cytolysin (CDC) family and a primary virulence factor of the intracellular pathogenListeria monocytogenes. LLO mediates rupture of phagosomal membranes, thereby releasing bacteria into the growth-permissive host cell cytosol. Several unique features of LLO allow its activity to be precisely regulated in order to facilitate phagosomal escape, intracellular growth, and cell-to-cell spread. To improve our understanding of the multifaceted contribution of LLO to the pathogenesis ofL. monocytogenes, we developed a screen that combined saturation mutagenesis and signature tags, termedinvivoanalysis bysaturation mutagenesis andsignature tags (IVASS). We generated a library of LLO mutant strains, each harboring a single amino acid substitution and a signature tag, by using the previously described pPL2 integration vector. The signature tags acted as molecular barcodes, enabling high-throughput, parallel analysis of 40 mutants in a single animal and identification of attenuated mutants by negative selection. Using the IVASS technique we were able to screen over 90% of the 505 amino acids present in LLO and identified 60 attenuated mutants. Of these, 39 LLO residues were previously uncharacterized and potentially revealed novel functions of the toxin during infection. The mutants that were subsequently analyzedin vivoeach conferred a 2- to 4-orders of magnitude loss in virulence compared to wild type, thereby validating the screening methods. Phenotypic analysis of the LLO mutant library using commonin vitrotechniques suggested that the functional contributions of some residues could only have been revealed throughin vivoanalysis.

scholarly journals Cytolysin-Dependent Escape of the Bacterium from the Phagosome Is Required but Not Sufficient for Induction of the Th1 Immune Response against Listeria monocytogenes Infection: Distinct Role of Listeriolysin O Determined by Cytolysin Gene Replacement

2007 ◽  
Vol 75 (8) ◽  
pp. 3791-3801 ◽  
Author(s):  
Hideki Hara ◽  
Ikuo Kawamura ◽  
Takamasa Nomura ◽  
Takanari Tominaga ◽  
Kohsuke Tsuchiya ◽  
...  
Keyword(s):  
Immune Response ◽  
Listeria Monocytogenes ◽  
Virulence Factor ◽  
Protective Immunity ◽  
Gene Replacement ◽  
Listeriolysin O ◽  
Listeria Ivanovii ◽  
Ifn Γ

ABSTRACT Listeria monocytogenes evades the antimicrobial mechanisms of macrophages by escaping from the phagosome into the cytosolic space via a unique cytolysin that targets the phagosomal membrane, listeriolysin O (LLO), encoded by hly. Gamma interferon (IFN-γ), which is known to play a pivotal role in the induction of Th1-dependent protective immunity in mice, appears to be produced, depending on the bacterial virulence factor. To determine whether the LLO molecule (the major virulence factor of L. monocytogenes) is indispensable or the escape of bacteria from the phagosome is sufficient to induce IFN-γ production, we first constructed an hly-deleted mutant of L. monocytogenes and then established isogenic L. monocytogenes mutants expressing LLO or ivanolysin O (ILO), encoded by ilo from Listeria ivanovii. LLO-expressing L. monocytogenes was highly capable of inducing IFN-γ production and Listeria-specific protective immunity, while the hly-deleted mutant was not. In contrast, the level of IFN-γ induced by ILO-expressing L. monocytogenes was significantly lower both in vitro and in vivo, despite the ability of this strain to escape the phagosome and the intracellular multiplication at a level equivalent to that of LLO-expressing L. monocytogenes. Only a negligible level of protective immunity was induced in mice against challenge with LLO- and ILO-expressing L. monocytogenes. These results clearly show that escape of the bacterium from the phagosome is a prerequisite but is not sufficient for the IFN-γ-dependent Th1 response against L. monocytogenes, and some distinct molecular nature of LLO is indispensable for the final induction of IFN-γ that is essentially required to generate a Th1-dependent immune response.

scholarly journals Listeriolysin O as a Reporter To Identify Constitutive and In Vivo-Inducible Promoters in the Pathogen Listeria monocytogenes

2000 ◽  
Vol 68 (6) ◽  
pp. 3242-3250 ◽  
Author(s):  
Iharilalao Dubail ◽  
Patrick Berche ◽  
Alain Charbit
Keyword(s):  
Listeria Monocytogenes ◽  
Host Cells ◽  
Transcriptional Analysis ◽  
Listeriolysin O ◽  
Gram Positive ◽  
Genome Database ◽  
Inducible Promoters ◽  
Genes Encoding

ABSTRACT Listeria monocytogenes is a facultative intracellular gram-positive bacterium capable of growing in the cytoplasm of infected host cells. Bacterial escape from the phagosomal vacuole of infected cells is mainly mediated by the pore-forming hemolysin listeriolysin O (LLO) encoded by hly. LLO-negative mutants of L. monocytogenes are avirulent in the mouse model. We have developed a genetic system with hly as a reporter gene allowing the identification of both constitutive and in vivo-inducible promoters of this pathogen. Genomic libraries were created by randomly inserting L. monocytogenes chromosomal fragments upstream of the promoterless hly gene cloned into gram-positive and gram-negative shuttle vectors and expressed in an LLO-negative mutant strain. With this hly-based promoter trap system, combined with access to the L. monocytogenes genome database, we identified 20 in vitro-transcribed genes, including genes encoding (i) p60, a previously known virulence gene, (ii) a putative new hemolysin, and (iii) two proteins of the general protein secretion pathway. By using the hly-based system as an in vivo expression technology tool, nine in vivo-induced loci of L. monocytogenes were identified, including genes encoding (i) the previously known in vivo-inducible phosphatidylinositol phospholipase C and (ii) a putative N-acetylglucosamine epimerase, possibly involved in teichoic acid biosynthesis. The use of hly as a reporter is a simple and powerful alternative to classical methods for transcriptional analysis to monitor promoter activity in L. monocytogenes.

scholarly journals Morin inhibits Listeria monocytogenes virulence in vivo and in vitro by targeting listeriolysin O and inflammation

2020 ◽  
Author(s):  
Gen Li ◽  
Guizhen Wang ◽  
Meng Li ◽  
Li Li ◽  
Hongtao Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Host Immune System ◽  
Listeriolysin O ◽  
Inflammatory Reactions ◽  
Bacterial Proliferation ◽  
Aquaculture Industry ◽  
Infected Cells ◽  
Listeria Infection

Abstract Background: Listeria monocytogenes ( L. monocytogenes ) is a global opportunistic intracellular pathogen that can cause many diseases, including meningitis and abortion in humans and animals; thus, L. monocytogenes poses a great threat to public safety and the development of the aquaculture industry. The pore-forming toxin listeriolysin O (LLO) is one of the most important virulence factors of L. monocytogenes ; LLO can promote cytosolic bacterial proliferation and aid in evading the attacks of the host immune system. In addition, L. monocytogenes infection can trigger a series of severe inflammatory reactions. Results: Here, on the basis of our previous studies, we further confirmed that morin lacking anti-Listeria activity could inhibit LLO oligomerization and found that morin could effectively alleviate the inflammation induced by Listeria in vivo and in vitro and has an obvious protective effect on infected cells and mice. Conclusions: Thus, we further prove that morin is a valuable drug precursor to be developed for the treatment of Listeria infection.

scholarly journals Curcumin Promotes the Clearance of Listeria monocytogenes both In Vitro and In Vivo by Reducing Listeriolysin O Oligomers

2017 ◽  
Vol 8 ◽  
Author(s):  
Xuan Zhou ◽  
Bing Zhang ◽  
Yumei Cui ◽  
Shuiye Chen ◽  
Zihao Teng ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Listeriolysin O

scholarly journals Morin inhibits Listeria monocytogenes virulence in vivo and in vitro by targeting listeriolysin O and inflammation

2020 ◽  
Author(s):  
Gen Li ◽  
Guizhen Wang ◽  
Meng Li ◽  
Li Li ◽  
Hongtao Liu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Host Immune System ◽  
Listeriolysin O ◽  
Inflammatory Reactions ◽  
Bacterial Proliferation ◽  
Aquaculture Industry ◽  
Infected Cells ◽  
Listeria Infection

Abstract Background: Listeria monocytogenes (L. monocytogenes) is a global opportunistic intracellular pathogen that can cause many diseases, including meningitis and abortion in humans and animals; thus, L. monocytogenes poses a great threat to public safety and the development of the aquaculture industry. The pore-forming toxin listeriolysin O (LLO) is one of the most important virulence factors of L. monocytogenes; LLO can promote cytosolic bacterial proliferation and aid in evading the attacks of the host immune system. In addition, L. monocytogenes infection can trigger a series of severe inflammatory reactions.Results: Here, on the basis of our previous studies, we further confirmed that morin lacking anti-Listeria activity could inhibit LLO oligomerization and found that morin could effectively alleviate the inflammation induced by Listeria in vivo and in vitro and has an obvious protective effect on infected cells and mice.Conclusions: Thus, we further prove that morin is a valuable drug precursor to be developed for the treatment of Listeria infection.

scholarly journals Interleukin-15 May Be Responsible for Early Activation of Intestinal Intraepithelial Lymphocytes after Oral Infection with Listeria monocytogenes in Rats

1998 ◽  
Vol 66 (12) ◽  
pp. 5677-5683 ◽  
Author(s):  
Kenji Hirose ◽  
Hirohiko Suzuki ◽  
Hitoshi Nishimura ◽  
Akio Mitani ◽  
Junji Washizu ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Cell Receptor ◽  
Intraepithelial Lymphocytes ◽  
Oral Infection ◽  
Epithelial Cell Line ◽  
Intestinal Intraepithelial Lymphocytes ◽  
Interleukin 15 ◽  
Ifn Γ

ABSTRACT Exogenous interleukin-15 (IL-15) stimulates intestinal intraepithelial lymphocytes (i-IEL) from mice to proliferate and produce gamma interferon (IFN-γ) in vitro. To determine whether endogenous IL-15 is involved in activation of i-IEL during intestinal infection, we examined IL-15 synthesis by intestinal epithelial cells (i-EC) after infection with Listeria monocytogenes in rats. In in vitro experiments, invasion of L. monocytogenes into IEC-6 cells, a rat small intestine epithelial cell line, evidently induced IL-15 mRNA expression coincident with nuclear factor κB (NF-κB) activation, which is essential for IL-15 gene expression. IL-15 synthesis was detected in rat i-EC on day 1 after an oral inoculation of L. monocytogenes in vivo. The numbers of T-cell receptor (TCR) γδ+ T cells, NKR.P1+cells, and CD3+ CD8+ αα cells in i-IEL were significantly increased on day 1 after oral infection. The i-IEL from infected rats produced larger amounts of IFN-γ upon stimulation with immobilized anti-TCR γδ or anti-NKR.P1 monoclonal antibodies. These results suggest that IL-15 produced by i-EC may stimulate significant fractions of i-IEL to produce IFN-γ at an early phase of oral infection with L. monocytogenes.

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