Pathogen Listeria Monocytogenes (pathogen + listeria_monocytogene)

Distribution by Scientific Domains


Selected Abstracts


Importance of murine V,1+,, T cells expressing interferon-, and interleukin-17A in innate protection against Listeria monocytogenes infection

IMMUNOLOGY, Issue 2 2008
Satoru Hamada
Summary Murine ,, T cells participate in the innate immune response against infection by an intracellular pathogen Listeria monocytogenes. V,1+,, T cells coexpressing V,6 are a major ,, T-cell subpopulation induced at an early stage of L. monocytogenes infection in the livers of infected mice. To investigate the protective role of the V,6/V,1+,, T cells against L. monocytogenes infection, V,1 gene-deficient (V,1,/,) mice were analysed because these mice selectively lacked a V,6/V,1+,, T-cell subpopulation in the L. monocytogenes -infected liver. The V,1,/, mice showed increased bacterial burden in the liver and spleen, and decreased survival rate at an early stage of L. monocytogenes infection when compared to wild-type mice. Histological examination showed abscess-like lesions and unorganized distribution of macrophages in the liver of the V,1,/, mice but not in the wild-type mice after L. monocytogenes infection. The V,6/V,1+,, T cells produced interferon-, and interleukin-17A. All the results suggest that murine V,6/V,1+,, T cells control the innate protective response against L. monocytogenes infection through production of the proinflammatory cytokines interferon-, and interleukin-17A in the infected liver. [source]


CtsR controls class III heat shock gene expression in the human pathogen Listeria monocytogenes

MOLECULAR MICROBIOLOGY, Issue 4 2000
Shamila Nair
Stress proteins play an important role in virulence, yet little is known about the regulation of stress response in pathogens. In the facultative intracellular pathogen Listeria monocytogenes, the Clp ATPases, including ClpC, ClpP and ClpE, are required for stress survival and intracellular growth. The first gene of the clpC operon of L. monocytogenes encodes a homologue of the Bacillus subtilis CtsR repressor of stress response genes. An L. monocytogenes ctsR -deleted mutant displayed enhanced survival under stress conditions (growth in the presence of 2% NaCl or at 42°C), but its level of virulence in the mouse was not affected. The virulence of a wild-type strain constitutively expressing CtsR is significantly attenuated, presumably because of repression of the stress response. Regulation of the L. monocytogenes clpC, clpP and clpE genes was investigated using transcriptional fusions in B. subtilis as a host. The L. monocytogenes ctsR gene was placed under the control of an inducible promoter, and regulation by CtsR and heat shock was demonstrated in vivo in B. subtilis. The purified CtsR protein of L. monocytogenes binds specifically to the clpC, clpP and clpE regulatory regions, and the extent of the CtsR binding sites was defined by DNase I footprinting. Our results demonstrate that this human pathogen possesses a CtsR regulon controlling class III heat shock genes, strikingly similar to that of the saprophyte B. subtilis. This is the first description of a stress response regulatory gene in a pathogen. [source]


Comparative proteome analysis of secretory proteins from pathogenic and nonpathogenic Listeria species

PROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 6 2005
Matthias Trost
Abstract Extracellular proteins of bacterial pathogens play a crucial role in the infection of the host. Here we present the first comprehensive validation of the secretory subproteome of the Gram positive pathogen Listeria monocytogenes using predictive bioinformatic and experimental proteomic approaches. The previous original signal peptide (SP) prediction (Glaser et al., Science 2001, 294, 849,852) has been greatly improved by an in-depth analysis using seven different bioinformatic tools. Subsequent careful classification of the resulting data gives a probability dependent annotation of 121 putatively secreted proteins of which 45 are novel. Complementary proteomic analysis using both two-dimensional gel electrophoresis/matrix assisted laser desorption/ionization mass spectrometry and high performance liquid chromatography/electrospray ionization-mass spectrometry has identified 105,proteins in the culture supernatant of L.,monocytogenes. Among these, we were able to detect all the currently known virulence factors with an SP showing the importance of this subproteome and demonstrating the reliability of the techniques used. The comparison between the L.,monocytogenes wildtype and the nonpathogenic species Listeria innocua was performed to reveal proteins probably involved in pathogenicity and/or the adaptation to their respective lifestyles. In addition to the eight known virulence factors, all of which have no orthologous genes in L.,innocua, eight additional proteins have been identified that exhibit the typical key feature defining the known listerial virulence factors. Further significant differences between the two species are evident in the group of cell wall and secretory proteins that warrant further study. Our investigation clearly demonstrates that the major difference between the pathogenic and nonpathogenic species, noted in the comparative genome analysis, manifests itself strongest in the secretome. [source]


Mechanistic study of membrane concentration and recovery of Listeria monocytogenes

BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2005
Wan-Tzu Chen
Abstract Detection of the foodborne pathogen Listeria monocytogenes requires that food samples be processed to remove proteins and lipids, concentrate microorganisms to a detectable concentration, and recover the concentrated cells in a small volume compatible with micron-scale biochips. Mechanistic considerations addressed in this research include the roles of membrane structure, pore size, and detergents in maximizing recovery of cells from a complex biological fluid. The fluid in this case was a food sample (hotdog extract) inoculated with L. monocytogenes. This study showed how membrane filtration using a syringe filter is able to concentrate L. monocytogenes by 95× with up to 95% recovery of living microorganisms by concentrating 50 mL of food sample into a volume of 500 ,L. Tween 20 was added to the sample to prevent irreversible adsorption of the microorganism to the membrane and thereby help to ensure high recovery. Comparison of polycarbonate, mixed cellulose, nylon, and PVDF membranes with 0.2 to 0.45 ,m pores showed the 0.2 ,m polycarbonate membrane with straight through, mono-radial pores gives the highest recovery of living microorganisms. The mixed cellulose, nylon, and PVDF membranes have a fibrous structure whose characteristic openings are much larger than their effective pore size cut-offs of 0.22 or 0.45 ,m. We define conditions for rapid membrane-based cell concentration and recovery that has the potential to supplant enrichment steps that require a day or more. This approach has the added benefit of facilitating examination of a large amount of fluid volume by reducing its volume to a range that is compatible with the microliter scales of biochip or other biosensor detection systems. © 2004 Wiley Periodicals, Inc. [source]


A novel role for the LisRK two-component regulatory system in listerial osmotolerance

CLINICAL MICROBIOLOGY AND INFECTION, Issue 8 2005
R. D. Sleator
Abstract Understanding how pathogenic bacteria sense and respond to environmental signals, including those involved in triggering virulence gene expression, is a fundamental biological goal. It is now known that the two-component regulatory system LisRK has a novel role in osmosensing and osmoregulation in the intracellular foodborne pathogen Listeria monocytogenes. Furthermore, htrA, a gene linked to osmotolerance and virulence potential in L. monocytogenes, is now known to be under the transcriptional control of LisRK. [source]