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splenic norepinephrine and serum corticosterone level fluctuations associated with bacteria-induced stress.corticosterone (cort) and norepinephrine (ne), two effector molecules of the hypothalamic-pituitary-adrenal (hpa) and the sympathetic-lymphoid (sl) axes, respectively, differentially influence murine host resistance to listeria monocytogenes (lm). serum cort and splenic ne levels early (< or =24 h) after infection correlated positively with host resistance, as long as the lm burden did not exceed approximately 10(6) cfu lm per spleen. as previously reported, mice with right-circling preference ( ...200415316243
roles of reactive oxygen species and heme oxygenase-1 in modulation of alveolar macrophage-mediated pulmonary immune responses to listeria monocytogenes by diesel exhaust particles.diesel exhaust particles (dep) have been shown to suppress alveolar macrophage (am)-mediated pulmonary immune responses to listeria monocytogenes in vivo. in this study, effects of dep-derived reactive oxygen species (ros) and heme oxygenase (ho)-1 on am-mediated immune responses to l. monocytogenes were investigated. brown norway rats were intratracheally inoculated with 100,000 l. monocytogenes, and am were isolated at 7 days post-infection. exposure to dep or their organic extract (edep), but ...200415319486
immunosuppressive treatment inhibits the development of amebic liver abscesses in hamsters.the aim of the present study was to determine if the inflammation and/or immunosuppression induced by entamoeba histolytica may contribute to amebic invasion.200415328476
optimization of rapid detection of escherichia coli o157:h7 and listeria monocytogenes by pcr and application to field test.for rapid detection of escherichia coli o157:h7 and listeria monocytogenes, simple methods for sample preparation and pcr were established and applied to a field test. to improve specificity, primer sets lp43-lp44 and c(+)-d(-) were selected for e. coli o157:h7 and l. monocytogenes, respectively. through centrifugation and partial heat treatment after enrichment, e. coli o157:h7 and l. monocytogenes were detected at 1 initial cfu without genomic dna extraction in the culture and with artificiall ...200415330527
survival and recovery of viable but nonculturable listeria monocytogenes cells in a nutritionally depleted medium.survival of a desiccated five-strain listeria monocytogenes mixture during storage in sand at 4 degrees c for 2 months was determined using the acridine orange direct count method with novobiocin and plate counts. samples of inoculated sand were taken every 2 weeks, incubated at 37 degrees c for 6 h, stained with acridine orange, and then examined with a fluorescence microscope. elongated viable but nonculturable cells were most frequently observed during weeks 2 and 4. at weeks 6 and 8, most of ...200415330528
a validated pcr-based method to detect listeria monocytogenes using raw milk as a food model--towards an international standard.a pcr assay with an internal amplification control was developed for listeria monocytogenes. the assay has a 99% detection probability of seven cells per reaction. when tested against 38 l. monocytogenes strains and 52 nontarget strains, the pcr assay was 100% inclusive (positive signal from target) and 100% exclusive (no positive signal from nontarget). the assay was then evaluated in a collaborative trial involving 12 european laboratories, where it was tested against an additional 14 target a ...200415330529
high-resolution genotyping of listeria monocytogenes by fluorescent amplified fragment length polymorphism analysis compared to pulsed-field gel electrophoresis, random amplified polymorphic dna analysis, ribotyping, and pcr-restriction fragment length polymorphism analysis.the purpose of this study was to evaluate fluorescent amplified fragment length polymorphism (aflp) analysis for the inter- and intraspecies differentiation of a collection of 96 strains of listeria monocytogenes and 10 non-l. monocytogenes strains representing six other listeria species of different origin. the aflp technique was compared with three other molecular typing methods--ribotyping, random amplified polymorphic dna analysis (rapd), and pulsed-field gel electrophoresis (pfge)--in terms ...200415330530
thermal resistance of listeria monocytogenes, salmonella heidelberg, and escherichia coli o157:h7 at elevated temperatures.a continuous-flow apparatus was developed to measure thermal resistance (d- and z-values) of microorganisms at temperatures above 65 degrees c. this apparatus was designed to test whether vegetative microorganisms exhibited unusually high thermal resistance that prevented them from being completely eliminated at temperatures applicable to vacuum-steam-vacuum processes (116 to 157 degrees c). the apparatus was composed of a high-pressure liquid chromatography pump, a heating unit, and a cooling u ...200415330531
high-pressure processing of gorgonzola cheese: influence on listeria monocytogenes inactivation and on sensory characteristics.the presence of listeria monocytogenes on the rind of gorgonzola cheese is difficult to avoid. this contamination can easily occur as a consequence of handling during ripening. the aims of this study were to determine the efficiency of high-pressure processing (hpp) for inactivation of l. monocytogenes on cheese rind and to evaluate the influence of hpp treatments on sensory characteristics. gorgonzola cheese rinds, after removal, were inoculated (about 7.0 log cfu/g) with l. monocytogenes strai ...200415330532
fate of listeria monocytogenes in bovine manure-amended soil.the survival and growth of listeria monocytogenes in soil amended with bovine manure was studied under different environmental conditions of temperature, nutrients, and soil microflora. autoclaved soil was compared with unautoclaved soil for assessing the influence of competitive soil microflora on the survival of l. monocytogenes. initial l. monocytogenes cell numbers of 5 to 6 log cfu/g survived for up to 43, 43, and 14 days in manure-amended autoclaved soil at 5, 15, and 21 degrees c, respect ...200415330533
optimizing concentration and timing of a phage spray application to reduce listeria monocytogenes on honeydew melon tissue.a phage cocktail was applied to honeydew melon pieces 1, 0.5, and 0 h before contamination with listeria monocytogenes strain lcdc 81-861 and 0.5, 1, 2, and 4 h after contamination. the phage application was most effective when applied 1, 0.5, or 0 h before contamination with l. monocytogenes, reducing pathogen populations by up to 6.8 log units after 7 days of storage. this indicates that under commercial conditions, if contamination occurs at the time of cutting, phage would have to be applied ...200415330534
effects of high-pressure processing on the safety, quality, and shelf life of ready-to-eat meats.ready-to-eat (rte) meats (low-fat pastrami, strassburg beef, export sausage, and cajun beef) were pressure treated at 600 mpa, 20 degrees c, for 180 s to evaluate the feasibility of using high-pressure processing (hpp) for the safe shelf-life extension of these products. after processing, samples were stored at 4 degrees c for 98 days during which time microbiological enumeration and enrichments were performed. additionally, sensory analyses were undertaken to determine consumer acceptability an ...200415330538
exploitation of host cell cytoskeleton and signalling during listeria monocytogenes entry into mammalian cells.deciphering how listeria monocytogenes exploits the host cell machinery to invade mammalian cells during infection isa key issue for the understanding how this food-borne pathogen causes a pleiotropic disease ranging from gastro-enteritis to meningitis and abortions. using multidisciplinary approaches, essentially combining bacterial genetics and cell biology, we have identified two bacterial proteins critical for entry into target cells, inla and inlb. their cellular ligands have been also iden ...200415332304
republication of the article "exploitation of host cell cytoskeleton and signalling during listeria monocytogenes entry into mammalian cells". 200415332305
[design of a hazard analysis and critical control points (haccp) plan to assure the safety of a bologna product produced by a meat processing plant].the hazard analysis and critical control point (haccp) is a systematic integral program used to identify and estimate the hazards (microbiological, chemical and physical) and the risks generated during the primary production, processing, storage, distribution, expense and consumption of foods. to establish a program of haccp has advantages, being some of them: to emphasize more in the prevention than in the detection, to diminish the costs, to minimize the risk of manufacturing faulty products, ...200415332359
potential influence of the first pcr cycles in real-time comparative gene quantifications.there is an underlying assumption in real-time pcr that the amplification efficiency is equal from the first cycles until a signal can be detected. in this study, we evaluated this assumption by analyzing genes with known gene copy number using real-time pcr comparative gene quantifications. listeria monocytogenes has six 23s rrna gene copies and one copy of the hlya gene. we determined 23s rrna gene copy numbers between 0.9 and 1.6 relative to hlya when applying the comparative gene quantificat ...200415335216
involvement of the mpo operon in resistance to class iia bacteriocins in listeria monocytogenes.high resistance to class iia bacteriocins in listeria monocytogenes has been clearly linked to lack of expression of the mptacd operon, encoding the eiit man mannose pts permease. also, intermediate resistance has been associated with membrane phospholipid modifications in the spontaneous mutants l. monocytogenes b73-v1 and b73-v2. we constructed a new mutant of l. monocytogenes that was interrupted in mpoa, and which also exhibited an intermediate resistance phenotype. the mpoabcd operon putati ...200415336400
role of lipid rafts in e-cadherin-- and hgf-r/met--mediated entry of listeria monocytogenes into host cells.listeria monocytogenes uptake by nonphagocytic cells is promoted by the bacterial invasion proteins internalin and inlb, which bind to their host receptors e-cadherin and hepatocyte growth factor receptor (hgf-r)/met, respectively. here, we present evidence that plasma membrane organization in lipid domains is critical for listeria uptake. cholesterol depletion by methyl-beta-cyclodextrin reversibly inhibited listeria entry. lipid raft markers, such as glycosylphosphatidylinositol-linked protein ...200415337781
soft listeria: actin-based propulsion of liquid drops.we study the motion of oil drops propelled by actin polymerization in cell extracts. drops deform and acquire a pearlike shape under the action of the elastic stresses exerted by the actin comet, a tail of cross-linked actin filaments. we solve this free boundary problem and calculate the drop shape taking into account the elasticity of the actin gel and the variation of the polymerization velocity with normal stress. the pressure balance on the liquid drop imposes a zero propulsive force if gra ...200415244616
essential oils: their antibacterial properties and potential applications in foods--a review.in vitro studies have demonstrated antibacterial activity of essential oils (eos) against listeria monocytogenes, salmonella typhimurium, escherichia coli o157:h7, shigella dysenteria, bacillus cereus and staphylococcus aureus at levels between 0.2 and 10 microl ml(-1). gram-negative organisms are slightly less susceptible than gram-positive bacteria. a number of eo components has been identified as effective antibacterials, e.g. carvacrol, thymol, eugenol, perillaldehyde, cinnamaldehyde and cin ...200415246235
listeria monocytogenes isolated from cold-smoked fish products in osaka city, japan.listeria monocytogenes contamination of ready-to-eat seafood products commercially available in osaka was examined between 1999 and 2000. l. monocytogenes was isolated from 12 (13%) of the 95 products tested. all positive samples were from cold-smoked fish with 9 being obtained during the summer. thirteen isolates of l. monocytogenes were typed by pulsed-field gel electrophoresis (pfge) and polymerase chain reaction (pcr)-based typing methods. isolates of the same serotype originating from the s ...200415246243
cd8+ t cell contraction is controlled by early inflammation.pathogen-specific cd8(+) t cells expand in number after infection and then their numbers invariably contract by 90-95%, leaving a stable memory cell pool. the chief features of this response are programmed early after infection; however, the factors regulating contraction are mostly undefined. here we show that antibiotic treatment before listeria monocytogenes infection induced numbers of protective memory cd8(+) t cells similar to those in control infected mice, by a pathway without contractio ...200415247915
chalk and cheese. 200415248310
looking at big brothers for clues. 200415250878
antimicrobial effects of sanitizers against planktonic and sessile listeria monocytogenes cells according to the growth phase.this study was designed to investigate the individual or combined effects of sanitizers on survival of planktonic or sessile listeria monocytogenes cells at different phase of growth. the sanitizers tested included: (i) acetic acid (ph 5.0), (ii) naoh (ph 12.0), (iii) 10% na2so4, (iv) 10% na2so4 and acetic acid (ph 5.0), (v) 10% na2so4 and naoh (ph 12.0), (vi) a quaternary ammonium (20 ppm) and (vii) glyceryl monolaurate (75 ppm). results revealed a great efficacy of alkaline treatments on both ...200415251203
single-chain fv antibody with specificity for listeria monocytogenes.single chain antibodies (scfv) exhibiting specific binding to listeria monocytogenes strains were isolated from a pool of random scfvs expressed on the surface of filamentous bacteriophages. positive selection (panning) using l. monocytogenes was used to enrich for phage clones with the desired binding affinity, and negative selection using l. innocua and l. ivanovii was used to remove phages expressing cross-reactive antibody fragments. a single phage clone, p4:a8, was selected using two indepe ...200415251420
characterization of mesentericin st99, a bacteriocin produced by leuconostoc mesenteroides subsp. dextranicum st99 isolated from boza.lactic acid bacteria isolated from boza, a cereal-fermented beverage from belogratchik, bulgaria, were screened for the production of bacteriocins. with the first screening, 13 of the 52 isolates inhibited the growth of listeria innocua and lactobacillus plantarum. the cell-free supernatant of one of these strains, classified as leuconostoc mesenteroides subsp. dextranicum st99, inhibited the growth of bacillus subtilis, enterococcus faecalis, several lactobacillus spp., lactococcus lactis subsp ...200415252717
oral immunization with recombinant listeria monocytogenes controls virus load after vaginal challenge with feline immunodeficiency virus.recombinant listeria monocytogenes has many attractive characteristics as a vaccine vector against human immunodeficiency virus (hiv). wild-type and attenuated listeria strains expressing hiv gag have been shown to induce long-lived mucosal and systemic t-cell responses in mice. using the feline immunodeficiency virus (fiv) model of hiv we evaluated recombinant l. monocytogenes in a challenge system. five cats were immunized with recombinant l. monocytogenes that expresses the fiv gag and delive ...200415254192
genome update: annotation quality in sequenced microbial genomes. 200415256543
intraspecific phylogeny and lineage group identification based on the prfa virulence gene cluster of listeria monocytogenes.listeria monocytogenes is a serious food-borne pathogen that can cause invasive disease in humans and other animals and has been the leading cause of food recalls due to microbiological concerns in recent years. in order to test hypotheses regarding l. monocytogenes lineage composition, evolution, ecology, and taxonomy, a robust intraspecific phylogeny was developed based on prfa virulence gene cluster sequences from 113 l. monocytogenes isolates. the results of the multigene phylogenetic analys ...200415262937
chemical conjugation of heterologous proteins on the surface of cowpea mosaic virus.genetic economy leads to symmetric distributions of chemically identical subunits in icosaherdal and helical viruses. modification of the subunit genes of a variety of viruses has permitted the display of polypeptides on both the infectious virions and virus particles made in expression systems. icosahedral chimeric particles of this type often display novel properties resulting in high local concentrations of the insert. here we report an extension of this concept in which entire proteins were ...200415264868
an update on the medical management of listeriosis.it is still not quite well understood why there is no optimal or even a satisfactory antibiotic therapy for listeriosis. although almost all listeria strains that induce sepsis, meningitis and encephalitis, as well as many other manifestations--in particular, in immunocompromised individuals--are susceptible to most of the common antibiotics, the cure rate is only approximately 70%. the most effective regimen still consists of a combination of an aminopenicillin (amoxicillin or ampicillin) plus ...200415264987
neutrophil involvement in cross-priming cd8+ t cell responses to bacterial antigens.substantial cd8(+) t cell responses are generated after infection of mice with recombinant listeria monocytogenes strains expressing a model epitope (lymphocytic choriomeningitis virus np(118-126)) in secreted and nonsecreted forms. l. monocytogenes gains access to the cytosol of infected cells, where secreted ags can be accessed by the endogenous mhc class i presentation pathway. however, the route of presentation of the nonsecreted ag in vivo remains undefined. in this study we show that neutr ...200415265934
ena/vasp proteins: multifunctional regulators of actin cytoskeleton dynamics.the spatial and temporal regulation of the actin cytoskeleton is fundamental to several cellular processes as diverse as cell motility and immune responses. at the molecular level, the remodelling of the actin cytoskeleton depends on two key events: actin filament nucleation and elongation. seminal studies on the actin-based intracellular motility of the bacterial pathogen listeria monocytogenes have been instrumental for the characterisation of a class of actin filament elongating factors, the ...200414977545
paneth cell alpha-defensins from rhesus macaque small intestine.antimicrobial peptides are secreted by small intestinal paneth cells as components of innate immunity. to investigate the role of alpha-defensins in enteric host defenses in nonhuman primates, alpha-defensin cdnas were isolated, alpha-defensin peptides were purified from rhesus macaque small bowel, and the bactericidal activities of the peptides were measured. six rhesus enteric alpha-defensin (red) cdnas, red-1 to red-6, were identified in a jejunum cdna library; the deduced red peptides exhibi ...200414977952
identification of srv, a prfa-like regulator of group a streptococcus that influences virulence.we have identified a crp/fnr-like transcriptional regulator of streptococcus pyogenes that when inactivated attenuates virulence. the gene, named srv for streptococcal regulator of virulence, encodes a 240-amino-acid protein with 53% amino acid similarity to prfa, a transcriptional activator of virulence in listeria monocytogenes.200414977990
protective t cell response against intracellular pathogens in the absence of toll-like receptor signaling via myeloid differentiation factor 88.toll-like receptors (tlr) have been indicated as germline-encoded receptors for sensing a variety of pathogens. although the role of tlr in innate immunity is beyond question, their function in acquired immunity, in particular in t cell immunity, is less clear. here, we used experimental listeria monocytogenes infection of mice to analyze requirements for tlr2, tlr4 and the central tlr adaptor protein myeloid differentiation factor 88 (myd88) in the generation of specific t cell responses. we de ...200414978015
depletion of cd4+ t cells during immunization with nonviable listeria monocytogenes causes enhanced cd8+ t cell-mediated protection against listeriosis.immunization of mice with nonviable listeria monocytogenes generates an insufficient cd8(+) t cell response and consequently only limited protection against subsequent l. monocytogenes infection. we have recently demonstrated that depletion of regulatory cd4(+) t cells during immunization significantly enhances cd8(+) t cell responses. in the present study, we determined the impact of cd4(+) t cell depletion on the cd8(+) t cell response against heat-killed listeria. treatment of mice with anti- ...200414978123
differential roles of multiple signal peptidases in the virulence of listeria monocytogenes.most bacteria contain one type i signal peptidase (spase i) for cleavage of signal peptides from exported and secreted proteins. here, we identified a locus encoding three contiguous spase i genes in the genome of listeria monocytogenes. the deduced sip proteins (denoted sipx, sipy and sipz) are significantly similar to sips and sipt, the major spase i proteins of bacillus subtilis (38% to 44% peptidic identity). we studied the role of these multiple signal peptidases in bacterial pathogenicity ...200414982622
listeria monocytogenes virulence proteins induce surface expression of fas ligand on t lymphocytes.virulence factors secreted by listeria monocytogenes are known to interfere with host cellular signalling pathways. we investigated whether l. monocytogenes modulates t-cell receptor signalling by examining surface expression of proteins known to be upregulated on activated t cells. in vitro culture of murine splenocytes with l. monocytogenes resulted in a specific and dose-dependent upregulation of fas ligand (fasl). induction of fasl expression was also observed for pathogenic listeria ivanovi ...200414982640
listeria monocytogenes encephalitis mimicking west nile encephalitis.we present a case of a 50-year-old man who presented to winthrop-university hospital in the midst of the 2002 west nile encephalitis (wne) outbreak with the cardinal clinical findings of wne, ie, fever, encephalopathy, weakness, and muscle tremors. during the summer of 2002, several cases of aseptic meningitis/viral encephalitis were admitted to our emergency room weekly. in addition, cases of wne were being admitted at the same time. during this period we had 3 cases of wne. our patient present ...200414983142
use of pcr primers derived from a putative transcriptional regulator gene for species-specific determination of listeria monocytogenes.listeria monocytogenes is an opportunistic bacterial pathogen that has accounted for an important portion of human foodborne diseases worldwide. in this study, through comparative analysis of l. innocua and l. monocytogenes genomic sequences, we selected a l. monocytogenes specific gene (lmo0733) that has the potential for specific detection of l. monocytogenes. using pcr primers (lmo0733f and lmo0733r) derived from this gene, a specific fragment of 453 bp was amplified only from genomic dna of ...200414984777
bacterial infection of human hematopoietic stem cells induces monocytic differentiation.differentiation of hematopoietic stem cells (hscs) can be influenced by different stimuli, including cytotoxic agents, certain cytokines, and contact with pathogens. infection may result in dysregulation of these important progenitor cells and therefore interfere with the availability of blood cells. in this study we analyzed the effect of bacterial infection on hscs concerning surface marker expression and cytokine release. listeria monocytogenes and yersinia enterocolitica accelerated maturati ...200414987733
visualization of tumors and metastases in live animals with bacteria and vaccinia virus encoding light-emitting proteins.we have shown that bacteria injected intravenously into live animals entered and replicated in solid tumors and metastases. the tumor-specific amplification process was visualized in real time using luciferase-catalyzed luminescence and green fluorescent protein fluorescence, which revealed the locations of the tumors and metastases. escherichia coli and three attenuated pathogens (vibrio cholerae, salmonella typhimurium, and listeria monocytogenes) all entered tumors and replicated. similarly, ...200414990953
a contribution to the improvement of listeria monocytogenes enumeration in cold-smoked salmon.for the enumeration of listeria monocytogenes in food, a sensitive enumeration method based on membrane filtration followed by transfer of the filter to a selective medium has been developed. this study was carried out with cold-smoked salmon, a product likely to be contaminated with l. monocytogenes. the operating protocol utilizes three filtration runs in parallel (5, 15 and 30 ml) of a 1 in 10 dilution of the salmon suspension through 0.45-microm pore-size cellulose ester membranes, and then ...200414996455
incidence of listeria monocytogenes in two milk processing environments, and assessment of listeria monocytogenes blood agar for isolation.a year-long survey of two northern ireland milk processing plants for listeria monocytogenes was carried out. sample sites included the milk processing environment (walls, floors, drains, and steps), processing equipment, raw and pasteurised milk. the fda listeria-selective enrichment procedure was used to process samples and an additional agar medium, l. monocytogenes blood agar (lmba), was utilized as part of the isolation procedure in order to compare its performance to that of the recommende ...200414996460
bacteria-mediated dna transfer in gene therapy and vaccination.the use of live attenuated bacterial vaccine strains allows the targeted delivery of macromolecules to mammalian cells and tissues via the mucosal route. depending on their specific virulence mechanisms and inherent metabolic preferences, bacteria invade certain cell types and body niches where they consequently deliver their cargo. recently, the ability of attenuated strains of salmonella, shigella and yersinia spp., as well as listeria monocytogenes and invasive escherichia coli, to deliver eu ...200414998775
efficacy and tolerability of clo2-generating gloves.the transmission of pathogenic microorganisms by the hands of workers continues to be a problem in the medical field and the food industry. compliance with hand hygiene is often poor, and gloves may be contaminated after being donned and may transmit microorganisms. a novel, patented technology allows materials to be impregnated with microspheres that, when activated by light or moisture, generate clo2 at sustained rates to produce a disinfecting microatmosphere. gloves that were seeded with bac ...200414999631
cytotoxic t-lymphocyte-, and helper t-lymphocyte-oriented dna vaccination.dna vaccines have advantages over other types of vaccines in that they can induce strong cellular immune responses, namely cytotoxic t lymphocytes (ctl) and helper t lymphocytes (th). dna vaccines are therefore considered a promising alternative to attenuated live vaccines in the field of infectious diseases. so far, various dna vaccines have been generated and tried to induce a particular cellular immune response by virtue of recombinant dna technology. dna vaccines have been designed for effic ...200415000749
folding and stability of the leucine-rich repeat domain of internalin b from listeri monocytogenes.internalin b (inlb), a surface protein of the human pathogen listeria monocytogenes, promotes invasion into various host cell types by inducing phagocytosis of the entire bacterium. the n-terminal half of inlb (residues 36-321, inlb321), which is sufficient for this process, contains a central leucine-rich repeat (lrr) domain that is flanked by a small alpha-helical cap and an immunoglobulin (ig)-like domain. here we investigated the spectroscopic properties, stability and folding of inlb321 and ...200415003459
suppurative gastritis in balb/c mice infected with listeria monocytogenes via the intragastric route.suppurative gastritis was demonstrated in balb/c mice 3 days after intragastric inoculation with 10(9) organisms of listeria monocytogenes strain atcc19113 (serotype 3). also tested were four other strains of mice (c3h, c57bl/6, fvb and icr) and three other strains of l. monocytogenes (hpb 3 [serotype 4b], hpb 410 [serotype 1/2a] and hpb 503 [serotype 1/2b]). after inoculation with atcc19113 the numbers of bacteria found in the stomach wall were greater in c57bl/6 and icr mice than in c3h and fv ...200415003470
evaluation of the microfoss system for the detection of listeria species in environmental samples.the microfoss system was evaluated for its ability to detect listeria species in environmental samples. the sensitivity and specificity of the microfoss were determined in relation to a standard culture method for listeria detection. the sensitivities of both the microfoss and standard culture methods were similar (88.4%-microfoss, 90.7%-culture) based on the total number of positive results obtained by both methods. the microfoss system detected listeria spp. in 12 samples, which were not detec ...200415003682
cutting edge: long-lived cd8 memory and protective immunity in the absence of cd40 expression on cd8 t cells.cd8 t cells need cd4 t cells to develop into long-lived, functional memory cells that provide protection against pathogen rechallenge. we investigated whether signaling via cd40 expressed on the cd8 cells themselves is involved in this cooperation. in murine responses to listeria monocytogenes and lymphocytic choriomeningitis virus, we found no evidence of any requirement for cd40-cd40 ligand interaction at this level. no differences were observed between cd40(-/-) and cd40(+/+) cd8 t cells that ...200415004136
prolonged antigen presentation, apc-, and cd8+ t cell turnover during mycobacterial infection: comparison with listeria monocytogenes.we expressed the ctl epitope of ova (ova(257-264)) in an acute (listeria monocytogenes (lm)-ova) and a chronic intracellular pathogen (mycobacterium bovis (bcg)-ova), to evaluate the kinetics of ag presentation. lm-ova proliferated rapidly in vivo, resulting in profound lm-ova expansion within the first 24 h of infection, culminating in the generation of a potent cd8+ t cell response, which peaked on day 7 but underwent a rapid attrition subsequently. in contrast, bcg-ova exhibited reduced growt ...200415004149
increased dendritic cell numbers impair protective immunity to intracellular bacteria despite augmenting antigen-specific cd8+ t lymphocyte responses.dendritic cells (dcs) reside in tissues, where they function as sentinels, providing an essential link between innate and adaptive immunity. increasing the numbers of dcs in vivo augments t cell responses, and can cause dramatic ctl-dependent tumor regression. to determine whether greater dc numbers promoted t cell-mediated protection in the context of host defense against intracellular bacteria, we treated mice with flt3 ligand (flt3-l) to increase dcs in vivo and challenged them with listeria ...200415004177
biophysical parameters influence actin-based movement, trajectory, and initiation in a cell-free system.using a biochemically complex cytoplasmic extract to reconstitute actin-based motility of listeria monocytogenes and polystyrene beads coated with the bacterial protein acta, we have systematically varied a series of biophysical parameters and examined their effects on initiation of motility, particle speed, speed variability, and path trajectory. bead size had a profound effect on all aspects of motility, with increasing size causing slower, straighter movement and inhibiting symmetry-breaking. ...200415004224
listeria monocytogenes actin-based motility varies depending on subcellular location: a kinematic probe for cytoarchitecture.intracellular listeria monocytogenes actin-based motility is characterized by significant individual variability, which can be influenced by cytoarchitecture. l. monocytogenes was used as a probe to transmit information about structural variation among subcellular domains defined by mitochondrial density. by analyzing the movement of a large population of l. monocytogenes in ptk2 cells, we found that mean speed and trajectory curvature were significantly larger for bacteria moving in mitochondri ...200415004231
quantitative detection of listeria monocytogenes and listeria innocua by real-time pcr: assessment of hly, iap, and lin02483 targets and amplifluor technology.we developed and assessed real-time pcr (rti-pcr) assays for the detection and quantification of the food-borne pathogen listeria monocytogenes and the closely related nonpathogenic species l. innocua. the target genes were hly and iap for l. monocytogenes and lin02483 for l. innocua. the assays were 100% specific, as determined with 100 listeria strains and 45 non-listeria strains, and highly sensitive, with detection limits of one target molecule in 11 to 56% of the reactions with purified dna ...200415006755
characteristics of a new enantioselective thermostable dipeptidase from brevibacillus borstelensis bcs-1 and its application to synthesis of a d-amino-acid-containing dipeptide.a new thermostable dipeptidase gene was cloned from the thermophile brevibacillus borstelensis bcs-1 by genetic complementation of the d-glu auxotroph escherichia coli wm335 on a plate containing d-ala-d-glu. nucleotide sequence analysis revealed that the gene included an open reading frame coding for a 307-amino-acid sequence with an m(r) of 35,000. the deduced amino acid sequence of the dipeptidase exhibited 52% similarity with the dipeptidase from listeria monocytogenes. the enzyme was purifi ...200415006780
pbp2229-mediated nisin resistance mechanism in listeria monocytogenes confers cross-protection to class iia bacteriocins and affects virulence gene expression.it was previously shown that enhanced nisin resistance in some mutants was associated with increased expression of three genes, pbp2229, hpk1021, and lmo2487, encoding a penicillin-binding protein, a histidine kinase, and a protein of unknown function, respectively. in the present work, we determined the direct role of the three genes in nisin resistance. interruption of pbp2229 and hpk1021 eliminated the nisin resistance phenotype. interruption of hpk1021 additionally abolished the increase in ...200415006792
maternal listeriosis in pregnancy associated with measles virus infection.a case of maternal listeriosis associated with measles infection is described. maternal listeriosis without fetal or neonatal involvement is relatively rare. this case was diagnosed early and treated appropriately, and the baby showed no symptoms or signs of feto-maternal infection.200415009615
auto, a surface associated autolysin of listeria monocytogenes required for entry into eukaryotic cells and virulence.listeria monocytogenes is an opportunistic food-borne human and animal pathogen. several surface proteins expressed by this intracellular pathogen are critical for the infectious process. by in silico analysis we compared the surface protein repertories of l. monocytogenes and of the non-pathogenic species listeria innocua and identified a gene encoding a surface protein of l. monocytogenes absent in l. innocua. this gene that we named aut encodes a protein (auto) of 572 amino acids containing a ...200415009888
influence of bovine manure as fertilizer on the bacteriological quality of organic iceberg lettuce.to investigate the bacteriological quality, and the occurrence of selected pathogenic bacteria from organically grown iceberg lettuce fertilized with bovine manure in the form of compost, firm manure and slurry in a 2-year field trial.200415012817
the interplay between classical and alternative isoprenoid biosynthesis controls gammadelta t cell bioactivity of listeria monocytogenes.isoprenoids are synthesised either through the classical, mevalonate pathway, or the alternative, non-mevalonate, 2-c-methyl-d-erythritol 4-phosphate (mep) pathway. the latter is found in many microbial pathogens and proceeds via (e)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate (hmb-pp), a potent activator of human vgamma9/vdelta2 t cells. listeria monocytogenes is the only pathogenic bacterium known to contain both pathways concurrently. strategic gene knockouts demonstrate that either pathway i ...200415013758
listeria monocytogenes-induced endogenous endophthalmitis: bioultrasonic findings.to report bioultrasonic findings in listeria monocytogenes-induced endophthalmitis (lmie) that have not been described previously.200415013893
comparative genomic analysis of the sigb operon in listeria monocytogenes and in other gram-positive bacteria.the stress-responsive, alternative sigma factor sigmab has been described in members of three gram-positive genera, bacillus, listeria, and staphylococcus. in these bacteria, sigmab appears to play an important role in facilitating rapid adaptation to and survival in stressful environments. sigmab activity is regulated through a complex system of phosphatases and kinases encoded by rsb (regulator of sigma b) genes. we describe the sigb operon structure for the facultative intracellular pathogen ...200415018101
characterization of the calcium-binding sites of listeria monocytogenes inlb.the listeria monocytogenes protein inlb promotes invasion of mammalian cells through activation of the receptor tyrosine kinase met. the inlb n-cap, a approximately 40 residue part of the domain that binds met, was previously observed to bind two calcium ions in a novel and unusually exposed manner. because subsequent work raised questions about the existence of these calcium-binding sites, we assayed calcium binding in solution to the inlb n-cap. we show that calcium ions are bound with dissoci ...200415020228
does etanercept monotherapy enhance the risk of listeria monocytogenes meningitis? 200415020347
sortase b, a new class of sortase in listeria monocytogenes.sortases are transamidases that covalently link proteins to the peptidoglycan of gram-positive bacteria. the genome of the pathogenic bacterium listeria monocytogenes encodes two sortases genes, srta and srtb. the srta gene product anchors internalin and some other lpxtg-containing proteins to the listerial surface. here, we focus on the role of the second sortase, srtb. whereas srta acts on most of the proteins in the peptidoglycan fraction, srtb appears to target minor amounts of surface polyp ...200415028680
preventing listeria contamination in foods.keeping ready-to-eat foods cold is key to reducing listeriosis, a serious infection in humans. that's one of the conclusions of a recent food and drug administration risk assessment on the relationships between foodborne listeriosis and human health.200415032197
listeria monocytogenes and listeriosis: a review of hazard characterisation for use in microbiological risk assessment of foods.considerable effort has been put into the application of quantitative microbiological risk assessment for listeria monocytogenes, and data are available for england and wales (probably more so than most other countries) on the adverse health effects, together with incidence data on different age and risk groups for human l. monocytogenes infections. this paper reviews aspects of listeria and human listeriosis, especially from a public health perspective and provide hazard characterisation data, ...200415033265
growth of listeria monocytogenes in melon, watermelon and papaya pulps.growth of listeria monocytogenes in low-acid fruits (melon, watermelon and papaya) at different times of incubation and at temperatures of 10, 20 and 30 degrees c was studied. fruit pulp portions with an average ph of 5.87, 5.50 and 4.87 for melon, watermelon and papaya, respectively, were obtained aseptically, homogenized, weighed and inoculated with suspensions (approximately 10(2) cfu/g) of l. monocytogenes. generation times of 7.12, 13.03 and 15.05 h at 10 degrees c, 1.74, 2.17 and 6.42 h at ...200415033271
effects of several environmental factors on the anti-listeria monocytogenes activity of an essential oil of picea excelsa.the effects of several environmental factors on the anti-listeria monocytogenes activity of an essential oil of picea excelsa were explored by determination of active concentrations using two methods and with survival curves. in trial conditions, the serovars 1/2c and 4b behaved similarly. a dose of 0.2-0.3% (v/v) of essential oil was bactericidal for 10(5)-10(7) cells contained in 1 ml of tryptone soy broth yeast extract at ph 6 and 7 incubated at 13 and 37 degrees c and of medium supplemented ...200415033272
subpopulations of mouse blood monocytes differ in maturation stage and inflammatory response.blood monocytes are well-characterized precursors for macrophages and dendritic cells. subsets of human monocytes with differential representation in various disease states are well known. in contrast, mouse monocyte subsets have been characterized minimally. in this study we identify three subpopulations of mouse monocytes that can be distinguished by differential expression of ly-6c, cd43, cd11c, mbr, and cd62l. the subsets share the characteristics of extensive phagocytosis, similar expressio ...200415034056
the ly-6chigh monocyte subpopulation transports listeria monocytogenes into the brain during systemic infection of mice.mononuclear phagocytes can be used by intracellular pathogens to disseminate throughout the host. in the bloodstream these cells are generically referred to as monocytes. however, blood monocytes are a heterogeneous population, and the exact identity of the leukocyte(s) relevant for microbial spreading is not known. experiments reported in this study used listeria monocytogenes-infected mice to establish the phenotype of parasitized blood leukocytes and to test their role in systemic disseminati ...200415034057
attachment of listeria monocytogenes on ready-to-eat meats.five individual strains of listeria monocytogenes and a mixed cocktail of all five were studied for attachment on frankfurters, ham, bologna, and roast beef relative to their cell surface characteristics. the ratio of strongly attached (sessile) l. monocytogenes cells compared with total (sessile and planktonic) attached cells on ready-to-eat meats was also determined. because bacterial cell surfaces were characterized by net negative charge and hydrophobicity, electrostatic interaction chromato ...200415035357
temperature effect on listeria monocytogenes growth in the event of contamination of cooked pork products.the aim of this study was to describe the effect of temperature on the growth of listeria monocytogenes in the event of postprocess contamination of packaged pork meats. this study was carried out in two steps. in the first step, the effect of temperature on l. monocytogenes growth rates was determined in duplicates at 13 temperatures between 2 and 43 degrees c by turbidimetric methods and adjusted by a quantitative secondary model. then, seven sets of growth kinetics were collected by challenge ...200415035358
radiation resistance and virulence of listeria monocytogenes scott a following starvation in physiological saline.the influence of starvation on the resistance of listeria monocytogenes scott a to electron beam irradiation in 0.85% (wt/vol) nacl (saline) and in ground pork was investigated. exponential- or stationary-phase cells (control) were grown at 35 degrees c in tryptic soy broth supplemented with 0.6% yeast extract. washed cells were starved for 12 days in saline, and virulence of the pathogen was evaluated at 0, 8, and 12 days during starvation. samples of saline and irradiation-sterilized ground po ...200415035359
development and characterization of an antimicrobial packaging film coating containing nisin for inhibition of listeria monocytogenes.the purpose of this study was to develop and characterize a packaging film coating containing nisin. a spot-on-lawn assay was used to determine the effect of acid type (ascorbic, acetic, hydrochloric, lactic) and nisin level (equal increments from 10,000 iu to 9 iu) to be used in the formulation of the film coating. zones of inhibition were measured after incubation on tryptic soy agar (37 degrees c, 48 h). low-density polyethylene films coated with differing levels of nisin were characterized b ...200415035360
inhibition of listeria monocytogenes on the surface of individually packaged hot dogs with a packaging film coating containing nisin.the objective of this study was to determine the effectiveness of packaging films coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing 10,000, 7,500, 2,500, or 156.3 iu/ml nisin for controlling listeria monocytogenes on the surfaces of vacuum-packaged hot dogs. barrier film coated with a methylcellulose/hydroxypropyl methylcellulose-based solution containing nisin or no nisin (control) was heat sealed to form individual pouches. hot dogs were placed in control an ...200415035361
membrane fusion induced by the catalytic activity of a phospholipase c/sphingomyelinase from listeria monocytogenes.listeria monocytogenes is a bacterium responsible for localized and generalized infections in humans and animals. it has the ability to spread from the cytoplasm of an infected cell to neighboring cells without becoming exposed to the extracellular space. the bacterium secretes a phospholipase c (plc(lm)) that is active on glycerophospholipids, e.g., phosphatidylcholine, and on sphingomyelin; thus, plc(lm) should be described more appropriately as a phospholipase c/sphingomyelinase. we have obta ...200415035639
t cell responses to listeria monocytogenes.owing to its unique intracellular biology that allows it to gain access to the host cell cytosol, listeria monocytogenes induces potent, protective cd8 responses. the study of these responses has served as a paradigm to understand cell-mediated immunity to microbial pathogens. the availability of mutants specifically defective in unique aspects of the intracellular biology of this pathogen has greatly aided these studies. during the past few years, progress has been made to understand the contri ...200415036139
dendritic cells: the host achille's heel for mucosal pathogens?mucosal surfaces represent the main sites of interaction with environmental microorganisms and antigens. sentinel cells, including epithelial cells and dendritic cells (dcs), continuously sense the environment and coordinate defenses for the protection of mucosal tissues. dcs play a central role in the control of adaptive immune responses owing to their capacity to internalize foreign materials, to migrate into lymph nodes and to present antigens to naive lymphocytes. some pathogenic microorgani ...200415036324
the probiotic escherichia coli strain nissle 1917 interferes with invasion of human intestinal epithelial cells by different enteroinvasive bacterial pathogens.the probiotic escherichia coli strain nissle 1917 (mutaflor) of serotype o6:k5:h1 was reported to protect gnotobiotic piglets from infection with salmonella enterica serovar typhimurium. an important virulence property of salmonella is invasion of host epithelial cells. therefore, we tested for interference of e. coli strain nissle 1917 with salmonella invasion of int407 cells. simultaneous administration of e. coli strain nissle 1917 and salmonella resulted in up to 70% reduction of salmonella ...200415039098
injury recovery of foodborne pathogens in high hydrostatic pressure treated milk during storage.bacteria are expected to be injured or killed by high hydrostatic pressure (hhp). this depends on pressure levels, species and strain of the microorganism and subsequent storage. injured bacteria may be repaired which could affect the microbiological quality of foodstuffs with an important safety consideration especially in low acid food products. in this study two gram-positive (listeria monocytogenes ca and staphylococcus aureus 485) and two gram-negative (escherichia coli o157:h7 933 and salm ...200415039101
induction of protective cellular immunity against mycobacterium tuberculosis by recombinant attenuated self-destructing listeria monocytogenes strains harboring eukaryotic expression plasmids for antigen 85 complex and mpb/mpt51.we report here the induction of specific protective cellular immunity against mycobacterium tuberculosis by the employment of vaccination with recombinant attenuated listeria monocytogenes strains. we constructed self-destructing attenuated l. monocytogenes delta 2 strains carrying eukaryotic expression plasmids for the antigen 85 complex (ag85a and ag85b) and for mpb/mpt51 (mycobacterial protein secreted by m. bovis bcg/mycobacterial protein secreted by m. tuberculosis) molecules. infection of ...200415039321
toll-like receptor 2 is required for optimal control of listeria monocytogenes infection.the control of listeria monocytogenes infection depends on the rapid activation of the innate immune system, likely through toll-like receptors (tlr), since mice deficient for the common adapter protein of tlr signaling, myeloid differentiation factor 88 (myd88), succumb to listeria infection. in order to test whether tlr2 is involved in the control of infections, we compared the host response in tlr2-deficient mice with that in wild-type mice. here we show that tlr2-deficient mice are more susc ...200415039335
dna vaccination with gp96-peptide fusion proteins induces protection against an intracellular bacterial pathogen.effective vaccination using in vitro peptide-loaded heat-shock proteins (hsp), tumor-derived hsp and hsp fusion proteins has been shown in viral, parasite and tumor model systems. we demonstrate protective dna vaccination using gp96-peptide fusion proteins against the intracellular bacterial pathogen listeria monocytogenes in a mouse model. in contrast to previous studies using pathogen-derived hsp as vaccine vehicles, we used recombinant endogenous (mus musculus) gp96 (grp94) as a carrier for i ...200415039390
p47 gtpases: regulators of immunity to intracellular pathogens.activation of the innate immune system by interferon-gamma (ifn-gamma is crucial for host resistance to infection. ifn-gamma induces the expression of a wide range of mediators that undermine the ability of pathogens to survive in host cells, including a newly discovered family of 47-kda gtpases. elimination of different p47 gtpases in mice by gene targeting severely cripples ifn-gamma-regulated defence against toxoplasma gondii, listeria monocytogenes, mycobacterium spp. and other pathogens. in ...200415040583
prevalence of antimicrobial resistance in bacteria isolated from central nervous system specimens as reported by u.s. hospital laboratories from 2000 to 2002.bacterial infections of the central nervous system, especially acute infections such as bacterial meningitis require immediate, invariably empiric antibiotic therapy. the widespread emergence of resistance among bacterial species is a cause for concern. current antibacterial susceptibility data among central nervous system (cns) pathogens is important to define current prevalence of resistance.200415043754
listeria monocytogenes: comparative interpretation of mouse virulence assay.being an opportunistic bacterial pathogen, listeria monocytogenes demonstrates significant strain variations in virulence and pathogenicity. the availability of laboratory procedures to ascertain the pathogenic potential of l. monocytogenes bacteria would greatly enhance the control and prevention of listerial infections. as a method that measures all virulent determinants, mouse virulence assay has been frequently used for assessing l. monocytogenes virulence. the pathogenic potential of a give ...200415043883
a generic approach for the detection of whole listeria monocytogenes cells in contaminated samples using surface plasmon resonance.the opportunistic food pathogen listeria monocytogenes is of great concern to the food industry and its rapid detection is of major importance. this paper describes the detection of l. monocytogenes with a polyclonal antibody by means of a new subtractive inhibition assay using a biacore 3000 biosensor. incubating l. monocytogenes cells and antibody for a short period of time, followed by subsequent separation of free unbound antibody with a stepwise centrifugation process, allowed the detection ...200415046767
protection from bacterial infection by a single vaccination with replication-deficient mutant herpes simplex virus type 1.adaptive immune responses in which cd8(+) t cells recognize pathogen-derived peptides in the context of major histocompatibility complex class i molecules play a major role in the host defense against infection with intracellular pathogens. cells infected with intracellular bacteria such as listeria monocytogenes, salmonella enterica serovar typhimurium, or mycobacterium tuberculosis are directly lysed by cytotoxic cd8(+) t cells. for this reason, current vaccines for intracellular pathogens, su ...200415047818
mini-review: presentation of pathogen-derived antigens in vivo.most intracellular pathogens induce robust t cell responses upon infection of mammalian hosts. in most cases, these t cell responses are protective and result in pathogen clearance. it is therefore important to determine how t cells are primed and how they differentiate into cytokine-secreting and/or cytotoxic effector cells. in contrast to b cells, which recognize soluble ag, cd8(+) and cd4(+) t cells react to ag-derived peptides bound to mhc i or mhc ii molecules, respectively. therefore, eluc ...200415048701
in vitro transcription of the listeria monocytogenes virulence genes inlc and mpl reveals overlapping prfa-dependent and -independent promoters that are differentially activated by gtp.most known virulence genes of listeria monocytogenes are regulated by the transcriptional factor prfa. using our recently established in vitro transcription system, we have studied the prfa-dependent promoter (pinlc) regulating the expression of the small, secreted internalin c. prfa-dependent and prfa-independent transcription is observed starting from pinlc in vitro and in vivo, suggesting the presence of two apparently overlapping promoters both of which use the same -10 box. although the prf ...200415049809
gw domains of the listeria monocytogenes invasion protein inlb are required for potentiation of met activation.the listeria monocytogenes protein inlb promotes intracellular invasion by activating the receptor tyrosine kinase met. earlier studies have indicated that the lrr fragment of inlb is sufficient for met activation, but we show that this is not the case unless the lrr fragment is artificially dimerized through a disulphide bond. in contrast, activation of met proceeds through monomers of intact inlb and, at physiologically relevant concentrations, requires coordinated action in cis of both inlb n ...200415049825
biofilm formation by salmonella spp. and listeria monocytogenes on plastic surface.to investigate the biofilm formation by 122 salmonella spp. and 48 listeria monocytogenes strains on a plastic surface.200415059216
lack of apoptosis in listeria monocytogenes-infected thymocytes from mice fed with dietary lipids.the potential action of certain fatty acids has been studied since the early 1970s. numerous effects on immune system functions have been related to dietary lipid administration; therefore, several of them have been applied in the treatment of inflammatory disorders. nevertheless, n-3 polyunsaturated fatty acids may affect host resistance to infectious diseases. in addition, several studies have demonstrated that certain fatty acids are involved in apoptosis induction. here, we have examined the ...200415060735
exploitation of host cell cytoskeleton and signalling during listeria monocytogenes entry into mammalian cells.deciphering how listeria monocytogenes exploits the host cell machinery to invade mammalian cells during infection is a key issue for the understanding how this food-borne pathogen causes a pleiotropic disease ranging from gastro-enteritis to meningitis and abortions. using multidisciplinary approaches, essentially combining bacterial genetics and cell biology, we have identified two bacterial proteins critical for entry into target cells, inla and inlb. their cellular ligands have been also ide ...200415060982
atypical colonial morphology and low recoveries of listeria monocytogenes strains on oxford, palcam, rapid'l.mono and aloa solid media.the performance of four commercial media, polymyxin-acriflavine-licl-ceftazidime-aesculin-mannitol (palcam), oxford, rapid'l.mono (bio-rad, marne la coquette, france) and agar listeria according to ottaviani and agosti (aloa: aes laboratoire, combourg, france; biolife, milan, italy), used to detect and enumerate 176 belgian strains of listeria monocytogenes of human and food origin, was evaluated. four strains showed a low recovery and/or atypical colonies on one or more media. these results sho ...200415063065
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