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the structure of the salmonella typhimurium type iii secretion system needle shows divergence from the flagellar system.the type iii secretion system (t3ss) is essential for the infectivity of many pathogenic gram-negative bacteria. the t3ss contains proteins that form a channel in the inner and outer bacterial membranes, as well as an extracellular needle that is used for transporting and injecting effector proteins into a host cell. the homology between the t3ss and the bacterial flagellar system has been firmly established, based upon both sequence similarities between respective proteins in the two systems an ...201020060835
osmoregulated periplasmic glucans synthesis gene family of shigella flexneri.osmoregulated periplasmic glucans (opgs) of food- and water-borne enteropathogen shigella flexneri were characterized. opgs were composed of 100% glucose with 2-linked glucose as the most abundant residue with terminal glucose, 2-linked and 2,6-linked glucose also present in high quantities. most dominant backbone polymer chain length was seven glucose residues. individual genes from the opg gene family comprising of a bicistronic operon opggh, opgb, opgc and opgd were mutagenized to study their ...201020062978
tracking the dynamic interplay between bacterial and host factors during pathogen-induced vacuole rupture in real time.escape into the host cell cytosol following invasion of mammalian cells is a common strategy used by invasive pathogens. this requires membrane rupture of the vesicular or vacuolar compartment formed around the bacteria after uptake into the host cell. the mechanism of pathogen-induced disassembly of the vacuolar membrane is poorly understood. we established a novel, robust and sensitive fluorescence microscopy method that tracks the precise time point of vacuole rupture upon uptake of gram-nega ...201020070313
the extreme c terminus of shigella flexneri ipab is required for regulation of type iii secretion, needle tip composition, and binding.type iii secretion systems (t3sss) are widely distributed virulence determinants of gram-negative bacteria. they translocate bacterial proteins into host cells to manipulate them during infection. the shigella t3ss consists of a cytoplasmic bulb, a transmembrane region, and a hollow needle protruding from the bacterial surface. the distal tip of mature, quiescent needles is composed of ipad, which is topped by ipab. physical contact with host cells initiates secretion and leads to assembly of a ...201020086081
th17 cells are the dominant t cell subtype primed by shigella flexneri mediating protective immunity.the t cell response to shigella, the causative agent of bacillary dysentery, remains poorly understood. using a murine model of infection, we report that shigella flexneri primes predominately il-17a- and il-22-producing th17 cells. shigella-specific th1 cells are only significantly induced on secondary infection, whereas specific th2 and cd8(+) t cells are undetectable. apart from th17 cells that are primed in a mhc class ii- and il-6-dependent, but il12/23p40-independent manner, we identified ...201020089698
identification of active site residues in the shigella flexneri glucosyltransferase gtrv.the serotype-specific glucosyltransferase, gtrv, is responsible for glucosylation of the o-antigen repeating unit of shigella flexneri serotype 5a strains. gtrv is an integral inner membrane protein with two essential periplasmic loops: the large loop 2 and the c-terminal loop 10. in this study, the full length of the loop 2 was shown to be necessary for gtrv function. site-directed mutagenesis within this loop revealed that conserved aromatic and charged amino acids have a critical role in the ...201020334579
a soluble form of the pilus protein fima targets the vdac-hexokinase complex at mitochondria to suppress host cell apoptosis.inhibition of apoptotic response of host cells during an early phase of infection is a strategy used by many enteroinvasive bacterial pathogens to enhance their survival. here, we report the identification of a soluble form of the pilus protein fima from the culture supernatants of e. coli k1, salmonella, and shigella that can potently inhibit bax-mediated release of cytochrome c from isolated mitochondria. similar to the infected cells, hct116 cells stably expressing fima display a delay in the ...201020347420
34 kda momp of shigella flexneri promotes tlr2 mediated macrophage activation with the engagement of nf-kappab and p38 map kinase signaling.the 34 kda major outer membrane protein (momp) of shigella flexneri 2a induces combinatorial expression of tlr2 and tlr6 on peritoneal macrophages of balb/c mice. between the two best-characterized tlrs, to date, tlr2 and tlr4, which are chiefly responsible for recognizing majority of bacterial products, tlr2 alone participates in recognition of 34 kda momp. in addition to tlrs, momp enhances the mrna expression of myd88 and traf6 and induces the nuclear translocation of nf-kappab as well as act ...201020347487
long-term downregulation of protease-activated receptor-2 expression in distal colon in rats following bacillary dysentery.the aim of this study was to determine changes of par-2 expression in distal colon and the sensitivity of colonic muscle to sligrl-nh2, the par-2-activating peptide (par-2-ap) following bacillary dysentery. shigella flexneri was administrated intragastrically in healthy male rats to induce bacillary dysentery. the effect of sligrl-nh2 on the motility of colonic muscle strips were examined. the expression of par-2 was determined by immunohistochemistry and western blotting. intragastric administr ...201020347884
structure of shigella ipgb2 in complex with human rhoa: implications for the mechanism of bacterial guanine nucleotide exchange factor mimicry.a common theme in bacterial pathogenesis is the manipulation of eukaryotic cells by targeting the cytoskeleton. this is in most cases achieved either by modifying actin, or indirectly via activation of key regulators controlling actin dynamics such as rho-gtpases. a novel group of bacterial virulence factors termed the wxxxe family has emerged as guanine nucleotide exchange factors (gefs) for these gtpases. the precise mechanism of nucleotide exchange, however, has remained unclear. here we repo ...201020363740
innate ifn-gamma production by subsets of natural killer cells, natural killer t cells and gammadelta t cells in response to dying bacterial-infected macrophages.interferon-gamma (ifn-gamma) activation of macrophages is a crucial step in the early innate defence against bacterial infection. this innate ifn-gamma is thought to be produced mainly by natural killer (nk) cells through activation with interleukin (il)-12p70 secreted by macrophages and dendritic cells (dcs) that have sensed bacterial products. however, a number of reports have shown that bacterial stimuli are unable to induce macrophages and/or dcs to produce sufficient amounts of il-12p70 unl ...201020415785
production and immunogenicity of recombinant ferric enterobactin protein (fepa).ferric siderophore complexes are produced by most bacteria to acquire iron, a vital element. these complexes are transported across the outer membrane by receptor proteins commonly known as fepa (ferric enterobactin protein). in this study we attempted to evaluate the immunogenicity of the membrane protein fepa, aiming at inhibition of iron uptake to protect invasion of the host by the bacterium.201020418143
tracking the secretion of fluorescently labeled type iii effectors from single bacteria in real time.a large number of gram negative pathogens use a specialized needle-like molecular machine known as type iii secretion (t3s) system. this highly sophisticated molecular device consists of a basal body spanning the two bacterial membranes and a protruding needle structure that is connected to a distal translocator complex. the main features of the t3s system are (i) activation after host cellular membrane contact and (ii) the ability to "inject" effectors into host cells through the needle apparat ...201020419414
neutrophil antimicrobial proteins enhance shigella flexneri adhesion and invasion.shigella flexneri is an enteric pathogen that causes massive inflammation and destruction of the human intestinal epithelium. neutrophils are the first cells of the innate immune system recruited to the site of infection. these cells can attack microbes by phagocytosis, neutrophil extracellular trap (net) formation and degranulation. here, we investigated how neutrophil degranulation affects virulence and show that exposure of shigella to granular proteins enhances infection of epithelial cells. ...201020331641
the proteome of shigella flexneri 2a 2457t grown at 30 and 37 degrees c.to upgrade the proteome reference map of shigella flexneri 2a 2457t, the protein expression profiles of log phase and stationary phase cells grown at 30 and 37 degrees c were thoroughly analyzed using multiple overlapping narrow ph range (between ph 4.0 and 11.0) two-dimensional gel electrophoresis. a total of 723 spots representing 574 protein entries were identified by maldi-tof/tof ms, including the majority of known key virulence factors. 64 hypothetical proteins and six misannotated protein ...201020164057
prevalence of plasmid-mediated quinolone-resistance determinants in shigella flexneri isolates from anhui province, china.quinolones are used extensively to treat shigella flexneri infection, and plasmid-mediated quinolone resistance (pmqr) determinants were recently reported. a total of 26 s. flexneri isolates collected from anhui province, china, in 2005 were screened for pmqr determinants, bla gene, gyra and parc genes, by pcr and sequencing. pmqr determinants were present in 53.8% (14 of 26) of isolates and qnra(1), qnrs(1), qnrs(2), aac(6')-ib-cr and qepa were present in 30.8, 11.5, 3.8, 19.2 and 11.5% of thos ...201020203702
[rectal prolapse in a neonate with shigella diarrhea].a case of neonatal rectal prolapse during shigella diarrhea is described. a 10 days neonate exclusively breast fed, whose 2 years old brother has had the same process 2 weeks ago. medical treatment with intravenous ceftriaxone resolved rectal prolapse in 48 hours. stool cultures showed the presence of shigella flexneri ii resistant to amoxicillin; blood and cerebrospinal fluid, cultures were negative. conclusion: rectal prolapse is an uncommon complication seen in infants with shigella diarrhea. ...201020204227
shigella mediated depletion of macrophages in a murine breast cancer model is associated with tumor regression.a tumor promoting role of macrophages has been described for a transgenic murine breast cancer model. in this model tumor-associated macrophages (tams) represent a major component of the leukocytic infiltrate and are associated with tumor progression. shigella flexneri is a bacterial pathogen known to specificly induce apotosis in macrophages. to evaluate whether shigella-induced removal of macrophages may be sufficient for achieving tumor regression we have developed an attenuated strain of s. ...201020221397
high-throughput screening of the virulence regulator virf: a novel antibacterial target for shigellosis.shigella flexneri is a human enteropathogen that infects about 165 million people and claims more than 1 million lives per year worldwide. although shigellosis has been considered a disease of the "third world," like many other contagious diseases, it does occur in developed countries. the emergence of drug and multidrug-resistant strains of shigella emphasizes the need for novel antibiotic development. virf, an arac-type transcriptional regulator, is responsible for the expression of all downst ...201020237205
requirement for formin-induced actin polymerization during spread of shigella flexneri.actin polymerization in the cytosol and at the plasma membrane is locally regulated by actin nucleators. several microbial pathogens exploit cellular actin polymerization to spread through tissue. the movement of the enteric pathogen shigella flexneri, both within the cell body and from cell to cell, depends on actin polymerization. during intercellular spread, actin polymerization at the bacterial surface generates protrusions of the plasma membrane, which are engulfed by adjacent cells. in the ...201019841078
virulence, inflammatory potential, and adaptive immunity induced by shigella flexneri msbb mutants.the ability of genetically detoxified lipopolysaccharide (lps) to stimulate adaptive immune responses is an ongoing area of investigation with significant consequences for the development of safe and effective bacterial vaccines and adjuvants. one approach to genetic detoxification is the deletion of genes whose products modify lps. the msbb1 and msbb2 genes, which encode late acyltransferases, were deleted in the shigella flexneri 2a human challenge strain 2457t to evaluate the virulence, infla ...201019884336
a bacterial e3 ubiquitin ligase ipah9.8 targets nemo/ikkgamma to dampen the host nf-kappab-mediated inflammatory response.nf-kappab (nuclear factor kappab) has a pivotal role in many cellular processes, including the inflammatory and immune responses and, therefore, its activation is tightly regulated by the ikk (ikappab kinase) complex and by ikappabalpha degradation. when shigella bacteria multiply within epithelial cells they release peptidoglycans, which are recognized by nod1 and stimulate the nf-kappab pathway, thus leading to a severe inflammatory response. here, we show that ipah9.8, a shigella effector pos ...201020010814
identification of antibacterial and antifungal pharmacophore sites for potent bacteria and fungi inhibition: indolenyl sulfonamide derivatives.synthesis of seven new indolenyl sulfonamides, have been prepared by the condensation reaction of indole-3-carboxaldehyde with different sulfonamides such as, sulphanilamide, sulfaguanidine, sulfathiazole, sulfamethoxazole, sulfisoxazole, sulfadiazine and sulfamethazine. these synthesized compounds have been used as potential ligands for complexation with some selective divalent transition metal ions (cobalt, copper, nickel & zinc). structure of the synthesized ligands has been deduced from thei ...201020005022
emergence of resistance to third-generation cephalosporin in shigella--a case report.the emergence of ciprofloxacin resistance in shigella has shifted the attention to cephalosporins. the first occurrence of third generation cephalosporin-resistant shigella flexneri was from france. this article reports the first case of cephalosporin-resistant s. flexneri from india. a 12-month-old child was admitted for a 20-day episode of loose stools, non-fetid, with mucus and blood. the stool sample showed the presence of blood and mucus and s. flexneri which was resistant to ampicillin, na ...201019955258
emergence of a new multidrug-resistant serotype x variant in an epidemic clone of shigella flexneri.shigella spp. are the causative agent of shigellosis with shigella flexneri serotype 2a being the most prevalent in developing countries. epidemiological surveillance in china found that a new serotype of s. flexneri appeared in 2001 and replaced serotype 2a in 2003 as the most prevalent serotype in henan province. the new serotype also became the dominant serotype in 7 of the 10 other provinces under surveillance in china by 2007. the serotype was identified as a variant of serotype x. it diffe ...201019955273
global analysis of a plasmid-cured shigella flexneri strain: new insights into the interaction between the chromosome and a virulence plasmid.shigella flexneri is an important human pathogen that causes dysentery, and remains a significant threat to public health, particularly in developing countries. the virulence of this pathogen is dependent on an acquired virulence plasmid. to investigate the crosstalk between the bacterial chromosome and the exogenous virulence plasmid, a virulence plasmid-cured strain was constructed using plasmid incompatibility. the global patterns of gene expression of this strain compared with the wild-type ...201020000779
inactivation of escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri on spinach leaves by x-ray.several recent foodborne disease outbreaks associated with leafy green vegetables, including spinach, have been reported. x-ray is a non-thermal technology that has shown promise for reducing pathogenic and spoilage bacteria on spinach leaves. inactivation of inoculated escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri on spinach leaves using x-ray at different doses (0.1, 0.2, 0.3, 0.5, 0.75, 1.0, 1.5 and 2.0 kgy) was studied. the effect of x-ray on col ...201019913687
effects of x-ray radiation on escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri inoculated on shredded iceberg lettuce.the main goal of this investigation was to study the efficacy of x-ray doses (0.1, 0.2, 0.3, 0.5, 0.75, 1.0, 1.5 and 2.0 kgy) on inoculated escherichia coli o157: h7, listeria monocytogenes, salmonella enterica and shigella flexneri on shredded iceberg lettuce. the second goal was to study the effect of x-ray on the inherent microflora counts and visual color of shredded iceberg lettuce during storage at 4 degrees c for 30 days. treatment with 1.0 kgy x-ray significantly reduced the population o ...201019913700
differentiation and identification of shigella spp. and enteroinvasive escherichia coli in environmental waters by a molecular method and biochemical test.both shigella spp. and enteroinvasive escherichia coli (eiec) are important human pathogens that are responsible for the majority of cases of endemic bacillary dysentery. however, they are difficult to identify and differentiate by biochemical tests or molecular methods alone. in this study, we developed a procedure to detect shigella spp. and eiec from environmental water samples using membrane filtration followed by nutrient broth enrichment, isolation using selective culture plates, and ident ...201019917511
solution nmr structures of proteins vpa0419 from vibrio parahaemolyticus and yiis from shigella flexneri provide structural coverage for protein domain family pfam 04175. 201019927321
characterization of wrss2 and wrss3, new second-generation virg(icsa)-based shigella sonnei vaccine candidates with the potential for reduced reactogenicity.live, attenuated shigella vaccine candidates, such as shigella sonnei strain wrss1, shigella flexneri 2a strain sc602, and shigella dysenteriae 1 strain wrsd1, are attenuated principally by the loss of the virg(icsa) protein. these candidates have proven to be safe and immunogenic in volunteer trials and in one study, efficacious against shigellosis. one drawback of these candidate vaccines has been the reactogenic symptoms of fever and diarrhea experienced by the volunteers, that increased in a ...201019932216
a new multiplex pcr for differential identification of shigella flexneri and shigella sonnei and detection of shigella virulence determinants.most of the multiplex pcr (mpcr) used to identify shigella do not discriminate between shigella species or serotypes. we designed a mpcr to differentiate between s. flexneri and s. sonnei strains based on the detection of markers associated with the she pathogenicity island described in shigella. in addition, specific primers were included to detect the shigella virulence determinants shet-1 and shet-2 enterotoxin genes. the analysis of 304 shigella strains from chile and 79 shigella strains fro ...201019765332
differential expression of enteric neuroimmune-network in invasive and acute watery diarrhoea.we aimed to evaluate the changes of nerve morphology and distribution of neurotransmitters and neuropeptides in the rectum of shigella flexneri-infected patients and in the duodenum of vibrio cholerae o1-infected patients. nerve morphology was observed by transmission electron microscopy. immunoreactivity of nerve growth factor (ngf), neurotransmitters and neuropeptides in tissues were studied by immunohistochemistry. ultrastructural analysis of intestinal biopsy revealed persisting axons degene ...201019650770
phenotypic and genotypic characterization of shigella spp. with reference to its virulence genes and antibiogram analysis from river narmada.water samples of the river narmada from origin to end were analyzed for the presence of shigellae. analysis of 40 water samples by biotyping, serotyping, and molecular typing were done. out of all 40 isolates, 23 were identified as shigella flexneri, 10 as shigella sonnei, and seven as shigella dysenteriae. serotyping was found to be a better identification method than biotyping since biotyping was not found to be very sharp. in the present investigation, amplified ribosomal dna restriction anal ...201019501495
mutagenesis and chemical cross-linking suggest that wzz dimer stability and oligomerization affect lipopolysaccharide o-antigen modal chain length control.in shigella flexneri, the polysaccharide copolymerase (pcp) protein wzz(sf) confers a modal length of 10 to 17 repeat units (rus) to the o-antigen (oag) component of lipopolysaccharide (lps). pcps form oligomeric structures believed to be related to their function. to identify functionally important regions within wzz(sf), random in-frame linker mutagenesis was used to create mutants with 5-amino-acid insertions (termed wzz(i) proteins), and dna sequencing was used to locate the insertions. anal ...201020453100
carbon metabolism of intracellular bacterial pathogens and possible links to virulence.new technologies such as high-throughput methods and 13c-isotopologue-profiling analysis are beginning to provide us with insight into the in vivo metabolism of microorganisms, especially in the host cell compartments that are colonized by intracellular bacterial pathogens. in this review, we discuss the recent progress made in determining the major carbon sources and metabolic pathways used by model intracellular bacterial pathogens that replicate either in the cytosol or in vacuoles of infecte ...201020453875
acid stress response in enteropathogenic gammaproteobacteria: an aptitude for survival.enteric bacteria such as escherichia coli have acquired a wide array of acid stress response systems to counteract the extreme acidity encountered when invading the host's digestive or urinary tracts. these acid stress response systems are both enzyme and chaperone based. the 3 main enzyme-based acid resistance pathways are glutamate-, arginine-, and lysine-decarboxylase pathways. they are under a complex regulatory network allowing the bacteria to fine tune its response to the external environm ...201020453931
microarray analysis of shigella flexneri-infected epithelial cells identifies host factors important for apoptosis inhibition.shigella flexneri inhibits apoptosis in infected epithelial cells. in order to understand the pro-survival effects induced by the bacteria, we utilized apoptosis-specific microarrays to analyze the changes in eukaryotic gene expression in both infected and uninfected cells in the presence and absence of staurosporine, a chemical inducer of the intrinsic pathway of apoptosis. the goal of this research was to identify host factors that contribute to apoptosis inhibition in infected cells.201020429941
modulation of shigella virulence in response to available oxygen in vivo.bacteria coordinate expression of virulence determinants in response to localized microenvironments in their hosts. here we show that shigella flexneri, which causes dysentery, encounters varying oxygen concentrations in the gastrointestinal tract, which govern activity of its type three secretion system (t3ss). the t3ss is essential for cell invasion and virulence. in anaerobic environments (for example, the gastrointestinal tract lumen), shigella is primed for invasion and expresses extended t ...201020436458
phenotypic characterization and genomic analysis of the shigella sonnei bacteriophage sp18.a novel bacteriophage that infects shigella sonnei was isolated from the gap river in korea, and its phenotypic and genomic characteristics were investigated. the virus, called sp18, showed morphology characteristic of the family myoviridae, and phylogenetic analysis of major capsid gene (gp23) sequences classified it as a t4-like phage. based on host spectrum analysis, it is lytic to s. sonnei, but not to shigella flexneri, shigella boydii or members of the genera escherichia and salmonella. py ...201020437154
antimicrobial resistance trends of shigella serotypes in new york city, 2006-2009.shigellosis is the third most common enteric bacterial infection in the united states. although infection is typically self-limiting, empiric treatment is often prescribed. because of increasing antimicrobial resistance to shigella, empiric treatment options are decreasing. identifying resistance patterns can inform empiric treatment recommendations. the goals of our study were to examine risk factors associated with antimicrobial resistance of shigella and examine issues related to empiric trea ...201020438349
genome-wide analysis of the h-ns and sfh regulatory networks in salmonella typhimurium identifies a plasmid-encoded transcription silencing mechanism.the conjugative inchi1 plasmid psfr27 from shigella flexneri 2a strain 2457t encodes the sfh protein, a paralogue of the global transcriptional repressor h-ns. sfh allows psfr27 to be transmitted to new bacterial hosts with minimal impact on host fitness, providing a 'stealth' function whose molecular mechanism has yet to be determined. the impact of the sfh protein on the salmonella enterica serovar typhimurium transcriptome was assessed and binding sites for sfh in the salmonella typhimurium g ...201020444106
molecular mechanisms of necroptosis: an ordered cellular explosion.for a long time, apoptosis was considered the sole form of programmed cell death during development, homeostasis and disease, whereas necrosis was regarded as an unregulated and uncontrollable process. evidence now reveals that necrosis can also occur in a regulated manner. the initiation of programmed necrosis, 'necroptosis', by death receptors (such as tumour necrosis factor receptor 1) requires the kinase activity of receptor-interacting protein 1 (rip1; also known as ripk1) and rip3 (also kn ...201020823910
a disulfide driven domain swap switches off the activity of shigella ipah9.8 e3 ligase.we show that the monomeric form of shigella ipah9.8 e3 ligase catalyses the ubiquitination of human u2af35 in vitro, providing a molecular mechanism for the observed in vivo effect. we further discover that under non-reducing conditions ipah9.8 undergoes a domain swap driven by the formation of a disulfide bridge involving the catalytic cysteine and that this dimer is unable to catalyse the ubiquitination of u2af35. the crystal structure of the domain-swapped dimer is presented. the redox inacti ...201020831869
the effects of x-ray radiation on escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri inoculated on whole roma tomatoes.in the last two decades several foodborne disease outbreaks associated with produce were reported. tomatoes, in particular, have been associated with several multi-state salmonella outbreaks. inactivation of inoculated escherichia coli o157:h7, listeria monocytogenes, salmonella enterica and shigella flexneri on whole roma tomato surfaces by x-ray at 0.1, 0.5, 0.75, 1.0, and 1.5 kgy was studied. the main purpose of this study was to achieve a 5 log reduction in consistent with the recommendation ...201020832685
formulation and immunogenicity studies of type iii secretion system needle antigens as vaccine candidates.bacterial infections caused by shigella flexneri, salmonella typhimurium, and burkholderia pseudomallei are currently difficult to prevent due to the lack of a licensed vaccine. here we present formulation and immunogenicity studies for the three type iii secretion system (ttss) needle proteins mxih(δ5), prgi(δ5), and bsal(δ5) (each truncated by five residues at its c terminus) as potential candidates for vaccine development. these antigens are found to be thermally stabilized by the presence of ...201020845448
formulation and immunogenicity of a potential multivalent type iii secretion system-based protein vaccine.the virulence of many pathogenic gram-negative bacteria is dependent upon their type iii secretion (tts) systems. here, we discuss initial formulation studies of five tts needle tip proteins ipad (shigella flexneri), bipd (burkholderia pseudomallei), sipd (salmonella spp.), lcrv (yersinia spp.), and pcrv (pseudomonas aeruginosa) as targets for subunit vaccines. excipient screening and subsequent assays lead to the selection of 10% sucrose and 5% dextrose as an optimal stabilizer combination for ...201020845449
dysbiosis of fecal microbiota in crohn's disease patients as revealed by a custom phylogenetic microarray.a custom phylogenetic microarray composed of small subunit ribosomal rna probes, representing ≈500 bacterial species from the human and animal gut, was developed and evaluated for analysis of gut microbial diversity using fecal samples from healthy subjects and crohn's disease (cd) patients.201020848492
defensins play a crucial role in protecting mice against oral shigella flexneri infection.an earlier study revealed that 4-day-old mice, but not older mice, were infected with invasive shigella strains. here we attempted to determine the underlying mechanism that induces inflammation in the intestines of neonate mice after oral shigella infection. wild-type balb/c mice of different ages (7, 14, and 35 days old) were orally administered gfp-expressing shigella flexneri 5a m90t strain (5 x 10⁹ cfu) and analyzed for colonization 6h following infection. we found that shigella localized i ...201020888321
viable but nonculturable state of foodborne pathogens in grapefruit juice: a study of laboratory.several foodborne human pathogens, when exposed to harsh conditions, enter viable but nonculturable (vbnc) state; however, still open is the question whether vbnc pathogens could be a risk for public health, because, potentially, they can resuscitate. moreover, cultural methods for food safety control were not able to detect vbnc forms of foodborne bacteria. particularly, it has not been established whether food chemophysical characteristics can induce vbnc state in contaminating pathogen bacter ...201020932087
domains of the shigella flexneri type iii secretion system ipab protein involved in secretion regulation.type iii secretion systems (t3sss) are key determinants of virulence in many gram-negative bacterial pathogens. upon cell contact, they inject effector proteins directly into eukaryotic cells through a needle protruding from the bacterial surface. host cell sensing occurs through a distal needle "tip complex," but how this occurs is not understood. the tip complex of quiescent needles is composed of ipad, which is topped by ipab. physical contact with host cells initiates secretion and leads to ...201020937761
combination of two separate binding domains defines stoichiometry between type iii secretion system chaperone ipgc and translocator protein ipab.type iii secretion systems (ttsss) utilized by enteropathogenic bacteria require the presence of small, acidic virulence-associated chaperones for effective host cell infection. we adopted a combination of biochemical and cellular techniques to define the chaperone binding domains (cbds) in the translocators ipab and ipac associated with the chaperone ipgc from shigella flexneri. we identified a novel cbd in ipab and furthermore precisely mapped the boundaries of the cbds in both translocator pr ...201020937829
expression of bacterial virulence factors and cytokines during in vitro macrophage infection by enteroinvasive escherichia coli and shigella flexneri: a comparative study.enteroinvasive escherichia coli (eiec) and shigella spp cause bacillary dysentery in humans by invading and multiplying within epithelial cells of the colonic mucosa. although eiec and shigella share many genetic and biochemical similarities, the illness caused by shigella is more severe. thus, genomic and structure-function molecular studies on the biological interactions of these invasive enterobacteria with eukaryotic cells have focused on shigella rather than eiec. here we comparatively stud ...201020944993
surveillance of shigellosis by real-time pcr suggests underestimation of shigellosis prevalence by culture-based methods in a population of rural china.shigellosis is a leading public health issue in china, especially in children under 5 years of age. the disease burden of shigellosis is usually underestimated by conventional culture. in this study, real-time pcr was applied to detect shigella infection in parallel with routine culture, to investigate the true burden of disease caused by shigella spp.201020951728
enhancement of reactive oxygen species production and chlamydial infection by the mitochondrial nod-like family member nlrx1.chlamydia trachomatis infections cause severe and irreversible damage that can lead to infertility and blindness in both males and females. following infection of epithelial cells, chlamydia induces production of reactive oxygen species (ros). unconventionally, chlamydiae use ros to their advantage by activating caspase-1, which contributes to chlamydial growth. nlrx1, a member of the nod-like receptor family that translocates to the mitochondria, can augment ros production from the mitochondria ...201020959452
ikkα contributes to canonical nf-κb activation downstream of nod1-mediated peptidoglycan recognition.during pathogen infection, innate immunity is initiated via the recognition of microbial products by pattern recognition receptors and the subsequent activation of transcription factors that upregulate proinflammatory genes. by controlling the expression of cytokines, chemokines, anti-bacterial peptides and adhesion molecules, the transcription factor nuclear factor-kappa b (nf-κb) has a central function in this process. in a typical model of nf-κb activation, the recognition of pathogen associa ...201020976174
atypical class 1 integron coexists with class 1 and class 2 integrons in multi-drug resistant shigella flexneri isolates from china.the antimicrobial resistance and the character of integrons were determined in 58 shigella flexneri strains isolated from china. all isolates were multi-drug resistant and found to carry integrons of class 1 (94.8%), class 2 (100%), or both (94.8%). no inti3 was detected. the typical class 1 integrons were found in conjugative plasmids and could be transferred to the recipient e. coli dh5α. the gene cassettes of typical class 1 integrons dfra17-aada5 and dfra12-orff-aada2 were detected in 54 str ...201020976456
notes from the field: emergence of shigella flexneri 2a resistant to ceftriaxone and ciprofloxacin --- south carolina, october 2010.on october 20, 2010, the south carolina department of health and environmental control and cdc began investigating a cluster of three diarrheal illnesses caused by multidrug-resistant shigella flexneri 2a. the index case occurred in a girl aged 2 years who experienced the onset of diarrhea on september 25 and was hospitalized the next day because of a seizure and fever. on september 30, her brother, aged 6 years, was hospitalized with vomiting, bloody diarrhea, and hyponatremia. three days later ...201021160457
[study on the integration site and arrangement of sfii and sfx prophages in shigella flexneri serotype 2b strains.]objective: to study the integration site and arrangement of sfii and sfx prophages in shigella flexneri serotype 2b strains. methods: a series of primers were designed based on potential integration site of sfii and sfx prophages in shigella flexneri serotype 2b strains, and pcr were performed for 50 serotype 2b strains to amplify special genes located in host and prophages. pcr products were sequenced to identify integration sites and arrangement of sfii and sfx. results: in all the serotype 2b ...201021162847
emergence of a novel shigella flexneri serotype 4s strain that evolved from a serotype x variant in china.this paper describes the first isolation of a new shigella flexneri serotype, designated 4s, in beijing, china. genotypic and phenotypic profiling suggests that this isolate is a clone of the s. flexneri serotype x variant reference strain. of particular concern is the multidrug resistance exhibited by this isolate.201021177890
cutting edge: nlrc5-dependent activation of the inflammasome.the nucleotide-binding domain leucine-rich repeat-containing proteins, nlrs, are intracellular sensors of pathogen-associated molecular patterns and damage-associated molecular patterns. a subgroup of nlrs can form inflammasome complexes, which facilitate the maturation of procaspase 1 to caspase 1, leading to il-1β and il-18 cleavage and secretion. nlrc5 is predominantly expressed in hematopoietic cells and has not been studied for inflammasome function. rna interference-mediated knockdown of n ...201021191067
enterobacteriaceae associated with eggs of podocnemis expansa and podocnemis unifilis (testudines:chelonia) in nonpolluted sites of national park of araguaia plains, brazil.fertile eggs of podocnemis expansa and podocnemis unifilis were investigated for the presence of enterobacteria, as these two endangered species have the potential for conservation measures that include egg transfer. knowledge of normal microflora associated with turtles and turtle eggs would help effectively manage the transfer of these eggs among institutions. thirty eggs of each species were collected, aseptically transferred, cracked inside plastic bags containing tetrathionate broth, and sp ...201021370647
ribonucleases and bacterial virulence.bacterial stress responses provide them the opportunity to survive hostile environments, proliferate and potentially cause diseases in humans and animals. the way in which pathogenic bacteria interact with host immune cells triggers a complicated series of events that include rapid genetic re-programming in response to the various host conditions encountered. viewed in this light, the bacterial host-cell induced stress response (hcisr) is similar to any other well-characterized environmental str ...201021375713
effects of backbone substitutions on the conformational behavior of shigella flexneri o-antigens: implications for vaccine strategy.the o-antigen (o-ag), the polysaccharide part of the lipopolysaccharide, is the major target of the serotype-specific protective humoral response elicited upon host infection by shigella flexneri, the main causal agent of the endemic form of bacillary dysentery. the o-ag repeat units (rus) of 12 s. flexneri serotypes share the tetrasaccharide backbone →2)-α-l-rhap-(1 → 2)-α-l-rhap-(1 → 3)-α-l-rhap-(1 → 3)-β-d-glcpnac-(1→, with site-selective glucosylation(s) and/or o-acetylation defining the ser ...201021030536
genetic characterization of atypical shigella flexneri isolated in korea.three types of serotypically atypical shigella flexneri strains were isolated from 2007 to 2008 in patients at the korea national institute of health (nih). these strains were characterized and compared with serologically typical s.flexneri. one type of strain either displayed nonreacting typing or grouping sera, reacting strongly only with polyb antisera, which indicates this strain is s. flexneri (polyb:un). the second type displayed reactions with one of the typing sera (iv) and did not bind ...201021030833
counting bacteria on a microfluidic chip.this paper reports a lab-on-a-chip device that counts the number of bacteria flowing through a microchannel. the bacteria number counting is realized by a microfluidic differential resistive pulse sensor (rps). by using a single microfluidic channel with two detecting arm channels placed at the two ends of the sensing section, the microfluidic differential rps can achieve a high signal-to-noise ratio. this method is applied to detect and count bacteria in aqueous solution. the detected rps signa ...201021035606
laboratory based surveillance of travel-related shigella sonnei and shigella flexneri in alberta from 2002 to 2007.abstract: between 2002 and 2007, travel related cases of shigella sonnei and s. flexneri in alberta, canada were acquired from central america, the indian subcontinent and north america. of this group, resistance to ciprofloxacin and nalidixic acid was identified in isolates from patients who had travelled to the indian subcontinent. this study provides a canadian perspective to a growing body of literature linking ciprofloxacin and nalidixic acid resistance to travel to the indian subcontinent. ...201021040566
safety, dose, immunogenicity, and transmissibility of an oral live attenuated shigella flexneri 2a vaccine candidate (sc602) among healthy adults and school children in matlab, bangladesh.in double-blind trials in bangladesh, 88 adults, and 79 children (8-10 years) were randomized to receive either a single oral dose of 1 × 10(4), 1 × 10(5) or 1 × 10(6)cfu of sc602 (a live, attenuated shigella flexneri 2a strain vaccine) or placebo. in the adult outpatient 1 × 10(6) cfu group, severe joint pain and body aches were reported by one and two vaccinees respectively. in the adult inpatient trial, sc602 was isolated from 3 volunteers, pre-vaccination antibody titers were high, and fourf ...201021040694
evidence of cellular immune response to outer membrane protein of salmonella typhimurium in patients with enthesitis-related arthritis subtype of juvenile idiopathic arthritis.enthesitis-related arthritis subtype of juvenile idiopathic arthritis (jia-era) clinically resembles reactive arthritis (rea). in patients with rea the immune response is targeted at the outer membrane protein (omp) of salmonella typhimurium. we studied the immune response in jia-era to s. typhimurium omp.201021041273
prevalence of shigellosis diarrhoea in a paediatrics population: hospital based survey in bangui, central african republic.shigellosis is still a major public health problem in sub-saharan countries, especially among children.201021045359
research progress in shigella in the postgenomic era.gram-negative, facultative intracellular anaerobes of the genus shigella, the principal etiologic agents of shigellosis, continue to pose a threat to public health. shigellosis causes 1.1 million deaths with over 164 million annual cases. the shigella spp. can be divided into four serogroups: shigella dysenteriae, shigella flexneri, shigella boydii and shigella sonnei. the completion of seven shigella genome sequences of representative strains from each of the shigella species has introduced an ...201021046319
[antibacterial antibodies in human immunoglobulins and sera: past and present].to measure levels of several types of antibacterial antibodies in preparations of normal human immunoglobulin as well as in samples of donor sera obtained in 1965 and 2009.201021061576
prevalence and characterization of human shigella infections in henan province, china, in 2006.in 2006, 3,531 fecal samples were collected from patients with diarrhea in henan province, china. a total of 467 (13.2%) shigella strains were isolated and serotyped. seventy-one shigella flexneri strains were characterized by mic determination, pulsed-field gel electrophoresis (pfge), and detection of genes encoding cephalosporin resistance. most infections were caused by s. flexneri variant x [iv:(7),8] (27.6%), s. sonnei (24.2%), and s. flexneri 2a (20.8%). however, large regional differences ...201021068291
the host outer membrane proteins ompa and ompc are associated with the shigella phage sf6 virion.assembly of dsdna bacteriophage is a precisely programmed process. potential roles of host cell components in phage assembly haven't been well understood. it was previously reported that two unidentified proteins were present in bacteriophage sf6 virion (casjens et al, 2004, j.mol.biol. 339, 379-394, fig. 2a). using tandem mass spectrometry, we have identified the two proteins as outer membrane proteins (omps) ompa and ompc from its host shigella flexneri. the transmission electron cryo-microsco ...201021071053
anaerobic environment of the intestine primes pathogenic shigella for infection.marteyn et al. have investigated the role of oxygen and the regulator fnr in infection by the intracellular enteric pathogen shigella flexneri. fnr is active under anaerobic conditions like those present in the lumen of the distal intestine. fnr causes elongation of a secretion apparatus required for bacterial entry into cells and represses secretion of proteins that trigger entry. higher oxygen levels present at the intestinal cell surface are sufficient to inactivate fnr, thereby derepressing ...201021073287
shigella flexneri spa15 crystal structure verified in solution by double electron electron resonance.shigella flexneri spa15 is a chaperone of the type 3 secretion system, which binds a number of effectors to ensure their stabilization prior to secretion. one of these effectors is ipgb1, a mimic of the human ras-like rho guanosine triphosphatase rhog. in this study, spa15 alone and in complex with ipgb1 has been studied by double electron electron resonance, an experiment that gives distance information showing the spacial separation of attached spin labels. this distance is explained by determ ...201021075116
entrapment of intracytosolic bacteria by septin cage-like structures.actin-based motility is used by various pathogens for dissemination within and between cells. yet host factors restricting this process have not been identified. septins are gtp-binding proteins that assemble as filaments and are essential for cell division. however, their role during interphase has remained elusive. here, we report that septin assemblies are recruited to different bacteria that polymerize actin. we observed that intracytosolic shigella either become compartmentalized in septin ...201021075354
extended-spectrum ß-lactamase production in shigella flexneri.emergence of multidrug-resistant strains of shigella is a growing concern across the globe. third-generation cephalosporins are used for treating infections caused by multidrug-resistant shigellae. however, resistance to these cephalosporin antibiotics due to extended-spectrum ß-lactamases, has emerged as a new problem. so far extended-spectrum ß-lactamases producing shigella has not been reported from pakistan. we report such a case in shigella flexneri from an 8-year old girl with acute dysent ...201021078255
enteropathogenic e. coli non-lee encoded effectors nleh1 and nleh2 attenuate nf-κb activation.enteric bacterial pathogens have evolved sophisticated strategies to evade host immune defences. some pathogens deliver anti-inflammatory effector molecules into the host cell cytoplasm via a type iii secretion system (t3ss). enteropathogenic escherichia coli (epec) inhibits inflammation by an undefined, t3ss-dependent mechanism. two proteins encoded outside of the epec locus of enterocyte effacement (lee) pathogenicity island, non-lee-encoded effector h1 (nleh1) and h2 (nleh2), display sequence ...201021091507
cell-cell propagation of nf-κb transcription factor and map kinase activation amplifies innate immunity against bacterial infection.the enteroinvasive bacterium shigella flexneri uses multiple secreted effector proteins to downregulate interleukin-8 (il-8) expression in infected epithelial cells. yet, massive il-8 secretion is observed in shigellosis. here we report a host mechanism of cell-cell communication that circumvents the effector proteins and strongly amplifies il-8 expression during bacterial infection. by monitoring proinflammatory signals at the single-cell level, we found that the activation of the transcription ...201021093316
isolation and characterization of shigella flexneri g3, capable of effective cellulosic saccharification under mesophilic conditions.a novel shigella strain (shigella flexneri g3) showing high cellulolytic activity under mesophilic, anaerobic conditions was isolated and characterized. the bacterium is gram negative, short rod shaped, and nonmotile and displays effective production of glucose, cellobiose, and other oligosaccharides from cellulose (avicel ph-101) under optimal conditions (40°c and ph 6.5). approximately 75% of the cellulose was hydrolyzed in modified atcc 1191 medium containing 0.3% cellulose, and the oligosacc ...201021097577
conformational changes in ipad from shigella flexneri upon binding bile salts provide insight into the second step of type iii secretion.shigella flexneri uses its type iii secretion apparatus (ttsa) to inject host-altering proteins into targeted eukaryotic cells. the ttsa is composed of a basal body and an exposed needle with invasion plasmid antigen d (ipad) forming a tip complex that controls secretion. the bile salt deoxycholate (doc) stimulates recruitment of the translocator protein ipab into the maturing ttsa needle tip complex. this process appears to be triggered by a direct interaction between doc and ipad. fluorescence ...201021126091
lactobacillus plantarum lipoteichoic acid down-regulated shigella flexneri peptidoglycan-induced inflammation.bacterial peptidoglycans (pgns) are recognized by the host's innate immune system. this process is mediated by the nod/card family of proteins, which induces inflammation by activating nuclear factor (nf)-κb. excessive activation of monocytes by shigella flexneri pgn (flexpgn) leads to serious inflammatory diseases such as intestinal bowel diseases (ibd) and crohn's disease. in this study, we examined whether lactobacillus plantarum lipoteichoic acid (plta) could attenuate the pro-inflammatory s ...201021129777
enteric glia protect against shigella flexneri invasion in intestinal epithelial cells: a role for s-nitrosoglutathione.enteric glial cells (egcs) are important regulators of intestinal epithelial barrier (ieb) functions. egc-derived s-nitrosoglutathione (gsno) has been shown to regulate ieb permeability. whether egcs and gsno protect the ieb during infectious insult by pathogens such as shigella flexneri is not known.201021139062
the shigella t3ss needle transmits a signal for mxic release, which controls secretion of effectors.type iii secretion systems (t3sss) are key determinants of virulence in many gram-negative bacteria, including animal and plant pathogens. they inject 'effector' proteins through a 'needle' protruding from the bacterial surface directly into eukaryotic cells after assembly of a 'translocator' pore in the host plasma membrane. secretion is a tightly regulated process, which is blocked until physical contact with a host cell takes place. host cell sensing occurs through a distal needle 'tip comple ...201021143311
antimicrobial resistance patterns and prevalence of class 1 and 2 integrons in shigella flexneri and shigella sonnei isolated in uzbekistan.abstract:201021143880
the type iii effectors nlee and nleb from enteropathogenic e. coli and ospz from shigella block nuclear translocation of nf-kappab p65.many bacterial pathogens utilize a type iii secretion system to deliver multiple effector proteins into host cells. here we found that the type iii effectors, nlee from enteropathogenic e. coli (epec) and ospz from shigella, blocked translocation of the p65 subunit of the transcription factor, nf-kappab, to the host cell nucleus. nf-kappab inhibition by nlee was associated with decreased il-8 expression in epec-infected intestinal epithelial cells. ectopically expressed nlee also blocked nuclear ...201020485572
regulation of high-affinity iron acquisition homologues in the tsetse fly symbiont sodalis glossinidius.sodalis glossinidius is a facultative intracellular bacterium that is a secondary symbiont of the tsetse fly (diptera: glossinidae). since studies with other facultative intracellular bacteria have shown that high-affinity iron acquisition genes are upregulated in vivo, we investigated the regulation of several sodalis genes that encode putative iron acquisition systems. these genes, sg1538 (hemt) and sg1516 (sita), are homologous to genes encoding periplasmic heme and iron/manganese transporter ...201020494987
[antibacterial activity of recombinant thanatin expressed by e.coli er2566].to express antibacterial peptide thanatin in the prokaryotic expression system and test its antibacterial activity.201020501392
the 33 carboxyl-terminal residues of spa40 orchestrate the multi-step assembly process of the type iii secretion needle complex in shigella flexneri.the type iii secretion apparatus (t3sa) is a central virulence factor of many gram-negative bacteria. its overall morphology consists of a cytoplasmic region, inner- and outer-membrane sections and an extracellular needle. in shigella, the length of the needle is regulated by spa32. to understand better the role of spa32 we searched for its interacting partners using a two-hybrid screen in yeast. we found that spa32 interacts with the 33 c-terminal residues (cc*) of spa40, a member of the conser ...201020507885
[analysis on bacillary dysentery surveillance data collected from the national surveillance system in 2007.].to improve the national surveillance plan on bacillary dysentery and to increase the sensitivity of the surveillance system on the disease.201020510059
["autophagy and microorganisms": hotspots of a mini-symposium]. 201020510155
crystallization and preliminary crystallographic studies of corc, a magnesium-ion transporter.corc is a magnesium transporter that is involved in the mg(2+)-efflux function of the cora transporter system, an mg(2+) channel, from shigella flexneri. native corc was purified and crystallized in the native form and in a ligand-free form and diffraction data sets were collected to 2.9 and 3.4 a resolution, respectively. the native corc crystals belonged to space group p2(1)2(1)2(1), with unit-cell parameters a = 64.31, b = 74.44, c = 132.78 a. the ligand-free corc crystals belonged to space g ...201020516599
a novel anti-virulence gene revealed by proteomic analysis in shigella flexneri 2a.abstract:201020540790
immunochemical studies of shigella flexneri 2a and 6, and shigella dysenteriae type 1 o-specific polysaccharide-core fragments and their protein conjugates as vaccine candidates.there is no licensed vaccine for the prevention of shigellosis. our approach to the development of a shigella vaccines is based on inducing serum igg antibodies to the o-specific polysaccharide (o-sp) domain of their lipopolysaccharides (lps). we have shown that low molecular mass o-sp-core (o-spc) fragments isolated from shigella sonnei lps conjugated to proteins induced significantly higher antibody levels in mice than the full length o-sp conjugates. this finding is now extended to the o-spc ...201020542498
protein refolding is required for assembly of the type three secretion needle.pathogenic gram-negative bacteria use a type three secretion system (ttss) to deliver virulence factors into host cells. although the order in which proteins incorporate into the growing ttss is well described, the underlying assembly mechanisms are still unclear. here we show that the ttss needle protomer refolds spontaneously to extend the needle from the distal end. we developed a functional mutant of the needle protomer from shigella flexneri and salmonella typhimurium to study its assembly ...201020543831
structures of the o-antigens of escherichia coli o13, o129, and o135 related to the o-antigens of shigella flexneri.o-polysaccharides (o-antigens) were isolated from escherichia coli o13, o129, and o135 and studied by chemical analyses along with 2d (1)h and (13)c nmr spectroscopy. they were found to possess a common -->2)-l-rha-(alpha1-->2)-l-rha-(alpha1-->3)-l-rha-(alpha1-->3)-d-glcnac-(beta1--> backbone, which is a characteristic structural motif of the o-polysaccharides of shigella flexneri types 1-5. in both the bacterial species, the backbone is decorated with lateral glucose residues or/and o-acetyl gr ...201020546712
generation of chitin-derived oligosaccharides toxic to pathogenic bacteria using chia74, an endochitinase native to bacillus thuringiensis.to demonstrate that an endochitinase (chia74) native to bacillus thuringiensis can be used to generate chitin-derived oligosaccharides (ogs) with antibacterial activity against a number of aetiological agents of disease, including bacteria that cause diarrhoeal and emetic syndromes in humans.201020557451
newer insights into the mechanism of action of psidium guajava l. leaves in infectious diarrhoea.psidium guajava l., myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. however, the effect of the leaf extract of p. guajava on the pathogenesis of infectious diarrhoea has not been studied. the present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of p. guajava on parameters associated with pathogenicity of infectious diarrhoea. the aim was to understand its possible mecha ...201020584265
escape of intracellular shigella from autophagy requires binding to cholesterol through the type iii effector, icsb.type iii secretion systems are present in many pathogenic bacteria and mediate the translocation of bacterial effectors into host cells. identification of host targets of these effectors is crucial for understanding bacterial virulence. icsb, a type iii secretion effector, helps shigella to evade the host autophagy defense system by binding to the autophagy protein, atg5. here, we show that icsb is able to interact specifically with cholesterol. the cholesterol binding domain (cbd) of icsb is lo ...201020599519
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