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virulent shigella flexneri affects secretion, expression, and glycosylation of gel-forming mucins in mucus-producing cells.mucin glycoproteins are secreted in large amounts by the intestinal epithelium and constitute an efficient component of innate immune defenses to promote homeostasis and protect against enteric pathogens. in this study, our objective was to investigate how the bacterial enteropathogen shigella flexneri, which causes bacillary dysentery, copes with the mucin defense barrier. we report that upon in vitro infection of mucin-producing polarized human intestinal epithelial cells, virulent s. flexneri ...201323876800
effects of subtherapeutic concentrations of antimicrobials on gene acquisition events in yersinia, proteus, shigella, and salmonella recipient organisms in isolated ligated intestinal loops of swine.to assess antimicrobial resistance and transfer of virulence genes facilitated by subtherapeutic concentrations of antimicrobials in swine intestines.201323879845
noncanonical inflammasome activation by intracellular lps independent of tlr4.gram-negative bacteria including escherichia coli, citrobacter rodentium, salmonella typhimurium, and shigella flexneri are sensed in an ill-defined manner by an intracellular inflammasome complex that activates caspase-11. we show that macrophages loaded with synthetic lipid a, e. coli lipopolysaccharide (lps), or s. typhimurium lps activate caspase-11 independently of the lps receptor toll-like receptor 4 (tlr4). consistent with lipid a triggering the noncanonical inflammasome, lps containing ...201323887873
infrequent cross-transmission of shigella flexneri 2a strains among villages of a mountainous township in taiwan with endemic shigellosis.shigellosis is rare in taiwan, with an average annual incidence rate of 1.68 cases per 100,000 persons in 2000-2007. however, the incidence rate for a mountainous township in eastern taiwan, zhuoxi, is 60.2 times the average rate for the entire country. traveling between zhuoxi's 6 villages (v1-v6) is inconvenient. disease transmission among the villages/tribes with endemic shigellosis was investigated in this study.201323899288
in situ structural analysis of the yersinia enterocolitica injectisome.injectisomes are multi-protein transmembrane machines allowing pathogenic bacteria to inject effector proteins into eukaryotic host cells, a process called type iii secretion. here we present the first three-dimensional structure of yersinia enterocolitica and shigella flexneri injectisomes in situ and the first structural analysis of the yersinia injectisome. unexpectedly, basal bodies of injectisomes inside the bacterial cells showed length variations of 20%. the in situ structures of the y. e ...201323908767
oxalis corniculata (oxalidaceae) leaf extract exerts in vitro antimicrobial and in vivo anticolonizing activities against shigella dysenteriae 1 (nt4907) and shigella flexneri 2a (2457t) in induced diarrhea in suckling mice.in this study, the extract of a green leafy vegetable oxalis corniculata (oxalidaceae) was evaluated for its in vitro antibacterial and in vivo anti colonizing effect against common intestinal pathogenic bacteria. methanolic extract (80%) of oxalis corniculata (oxalidaceae) leaf contained a polyphenol content of 910 mg gallic acid equivalent per gram of dry weight and the yield was 8%. the flavonoid content was 2.353 g quercetin equivalent per 100 g of the extract. in vitro studies indicated tha ...201323909903
metal-based carboxamide-derived compounds endowed with antibacterial and antifungal activity.a series of three bioactive thiourea (carboxamide) derivatives, n-(dipropylcarbamothioyl)-thiophene-2-carboxamide (l(1)), n-(dipropylcarbamothioyl)-5-methylthiophene-2-carboxamide (l(2)) and 5-bromo-n-(dipropylcarbamothioyl)furan-2-carboxamide (l(3)) and their cobalt(ii), copper(ii), nickel(ii) and zinc(ii) complexes (1)-(12) have been synthesized and characterized by their ir,(1)h-nmr spectroscopy, mass spectrometry and elemental analysis data. the crystal structure of one of the ligand, n-(dip ...201423914928
modulators of antibiotic activity from ipomoea murucoides.reinvestigation of the chcl3-soluble extract from the flowers of ipomoea murucoides, through preparative-scale recycling hplc, yielded three pentasaccharides of 11-hydroxyhexadecanoic acid, murucoidins xvii-xix, in addition to the known murucoidin iii and v, all of which were characterized by nmr spectroscopy and mass spectrometry. these compounds were found to be macrolactones of the known pentasaccharides simonic acid b and operculinic acid a. the acylating groups corresponded to acetic, (2s)- ...201323920226
identification and characterization of a novel shigella flexneri serotype yv in china.shigella flexneri is the major cause of bacterial shigellosis in developing countries. s. flexneri is divided into at least 19 serotypes, the majority of which are modifications of the same basic o-antigen by glucosylation and/or o-acetylation of its sugar residues by phage encoded serotype-converting genes. recently, a plasmid encoded phosphoethanolamine (petn) modification of the o-antigen has been reported, which is responsible for the presence of the masf iv-1 determinant and results in conv ...201323936172
lps unmasking of shigella flexneri reveals preferential localisation of tagged outer membrane protease icsp to septa and new poles.the shigella flexneri outer membrane (om) protease icsp (sopa) is a member of the enterobacterial omptin family of proteases which cleaves the polarly localised om protein icsa that is essential for shigella virulence. unlike icsa however, the specific localisation of icsp on the cell surface is unknown. to determine the distribution of icsp, a haemagglutinin (ha) epitope was inserted into the non-essential icsp om loop 5 using splicing by overlap extension (soe) pcr, and icsp(ha) was characteri ...201323936222
human naip and mouse naip1 recognize bacterial type iii secretion needle protein for inflammasome activation.inflammasome mediated by central nucleotide-binding and oligomerization domain (nod)-like receptor (nlr) protein is critical for defense against bacterial infection. here we show that type iii secretion system (t3ss) needle proteins from several bacterial pathogens, including salmonella typhimurium, enterohemorrhagic escherichia coli, shigella flexneri, and burkholderia spp., can induce robust inflammasome activation in both human monocyte-derived and mouse bone marrow macrophages. needle protei ...201323940371
shigella flexneri 3a outer membrane protein c epitope is recognized by human umbilical cord sera and associated with protective activity.shigella flexneri 3a is one of the five major strains of the shigella genus responsible for dysentery, especially among children, in regions of high poverty and poor sanitation. the outer membrane proteins (omp) of this bacterium elicit immunological responses and are considered a prime target for vaccine development. when injected into mice they elicit a protective immunological response against a lethal dose of the pathogen. the omps from s. flexneri 3a were isolated and resolved by two-dimens ...201323940590
o-antigen protects gram-negative bacteria from histone killing.beyond their traditional role of wrapping dna, histones display antibacterial activity to gram-negative and -positive bacteria. to identify bacterial components that allow survival to a histone challenge, we selected resistant bacteria from homologous escherichia coli libraries that harbor plasmids carrying pieces of the chromosome in different sizes. we identified genes required for exopolysaccharide production and for the synthesis of the polysaccharide domain of the lipopolysaccharide, called ...201323951089
structural insights into virb-dna complexes reveal mechanism of transcriptional activation of virulence genes.virb activates transcription of virulence genes in shigella flexneri by alleviating heat-stable nucleoid-structuring protein-mediated promoter repression. virb is unrelated to the conventional transcriptional regulators, but homologous to the plasmid partitioning proteins. we determined the crystal structures of virb hth domain bound by the cis-acting site containing the inverted repeat, revealing that the virb-dna complex is related to parb-pars-like complexes, presenting an example that a parb ...201323985969
analysis of different prognostic indicators for malnutrition and shigella flexneri infection among the children in bangladesh.the present study investigates into some socio-economic, demographic, and nutritional features that can predispose bangladeshi children to malnutrition and shigella flexneri infection. significant prognostic indicators associated with malnutrition were mother's illiteracy (unadjusted odds ratio, or = 2.580; 95% confidence interval, ci = 1.134-5.867 and adjusted odds ratio, ora, 3.814; 95% ci = 1.124-12.943), low birth weight (or = 3.143; 95% ci = 1.2-8.232 and ora = 2.404; 95% ci = 0.870-6.644) ...201223997331
small-molecule inhibitor of the shigella flexneri master virulence regulator virf.virf is an arac family transcriptional activator that is required for the expression of virulence genes associated with invasion and cell-to-cell spread by shigella flexneri, including multiple components of the type three secretion system (t3ss) machinery and effectors. we tested a small-molecule compound, se-1 (formerly designated ossl_051168), which we had identified as an effective inhibitor of the arac family proteins rhas and rhar, for its ability to inhibit virf. cell-based reporter gene ...201324002059
characterization and complete genome sequence of the shigella bacteriophage psf-1.shigellosis is a global health problem, and shigella flexneri is the major cause of this disease. in this study, we isolated a virulent siphoviridae bacteriophage (phage), psf-1, that infects s. flexneri. this phage was isolated from the han river in korea and was found to infect s. flexneri, shigella boydii, and shigella sonnei. one-step growth analysis revealed that this phage has a short latent period (10 min) and a large burst size (86.86 pfu/cell), indicating that psf-1 has good host infect ...201324012542
complete genome sequence of sfii, a serotype-converting bacteriophage of the highly prevalent shigella flexneri serotype 2a.sfii is a serotype-converting temperate bacteriophage of the highly prevalent shigella flexneri serotype 2a. we isolated the sfii phage from a wild-type strain of s. flexneri serotype 2a. here, we present the complete genome sequence of this phage.201324029753
molecular epidemiology of shigella spp strains isolated in two different metropolitam areas of southeast brazil.shigella spp., the human pathogen responsible for shigellosis, is highly infectious even at low levels. the incidence rate of shigellosis varies with geographical distribution, location human development index, and age groups, being higher among children aged under 5 years. in brazil, a few works indicate that shigellosis cases are underestimated, with s. flexneri and s. sonnei strains being the major agents responsible for the shigellosis cases. the present study used pulsed field gel electroph ...200924031415
proinflammatory signal transduction pathway induced by shigella flexneri porins in caco-2 cells.the recognition of bacterial components on the intestinal epithelial cells occurs through the toll-like receptors and is followed by the induction of an effective innate immune response. we analyzed receptor expression and signaling pathways involved in activation of human colon adenocarcinoma cells after stimulation with porins and lps of shigella flexneri. we also analyzed the expression and production of some cytokines, of intercellular adhesion molecule-1, of antimicrobial peptides human β-d ...200924031417
detection of shigella in lettuce by the use of a rapid molecular assay with increased sensitivity.a multiplex polymerase chain reaction (pcr) assay to be used as an alternative to the conventional culture method in detecting shigella and enteroinvasive escherichia coli (eiec) virulence genes ipah and ial in lettuce was developed. efficacy and rapidity of the molecular method were determined as compared to the conventional culture. lettuce samples were inoculated with different shigella flexneri concentrations (from 10 cfu/ml to 10(7) cfu/ml). dna was extracted directly from lettuce after ino ...201024031579
protective immunity by oral immunization with heat-killed shigella strains in a guinea pig colitis model.the protective efficacy of and immune response to heat-killed cells of monovalent and hexavalent mixtures of six serogroups/serotypes of shigella strains (shigella dysenteriae 1, shigella flexneri 2a, s. flexneri 3a, s. flexneri 6, shigella boydii 4, and shigella sonnei) were examined in a guinea pig colitis model. a monovalent or hexavalent mixture containing 1 × 10(7) of each serogroup/serotype of heat-killed shigella cells was administered orally on days 0, 7, 14 and 21. on day 28, the immuni ...201324033533
hypoxic stress, hepatocytes and caco-2 viability and susceptibility to shigella flexneri invasion.inflammation due to shigella flexneri can cause damage to the colonic mucosa and cell death by necrosis and apoptosis. this bacteria can reach the bloodstream in this way, and the liver through portal veins. hypoxia is a condition present in many human diseases, and it may induce bacterial translocation from intestinal lumen. we studied the ability of s. flexneri to invade rat hepatocytes and caco-2 cells both in normoxic and hypoxic microenvironments, as well as morphological and physiological ...201524037289
the zebrafish as a new model for the in vivo study of shigella flexneri interaction with phagocytes and bacterial autophagy.autophagy, an ancient and highly conserved intracellular degradation process, is viewed as a critical component of innate immunity because of its ability to deliver cytosolic bacteria to the lysosome. however, the role of bacterial autophagy in vivo remains poorly understood. the zebrafish (danio rerio) has emerged as a vertebrate model for the study of infections because it is optically accessible at the larval stages when the innate immune system is already functional. here, we have characteri ...201324039575
combination of extracts from aristolochia cymbifera with streptomycin as a potential antibacterial drug.the appearance of new antibiotic-resistant bacteria is a societal problem that requires the development of new alternative treatments. therefore, this work evaluated the antibacterial activity of ethanolic (ehi), dichloromethanic (edi) and hexanic (ehe) extracts from aristolochia cymbifera stems and the combination of these extracts with an antimicrobial drug to develop a new antibacterial therapy. the edi, ehe and ehi extracts were obtained by maceration using three different solvents. the mini ...201324040585
shigella flexneri enteritis in risk-taking hiv-infected msm. 201424055803
isolation and characterization of antimicrobial constituents of searsia chirindensis l. (anacardiaceae) leaf extracts.searsia chirindensis is used in south african traditional medicine for management of bacterial infections such as diarrhoea. aim of the study was to examine the phytochemical composition from the leaves of searsia chirindensis that is responsible for the ethnomedicinal use of this plant.201324060408
characterization of a novel fusion protein from ipab and ipad of shigella spp. and its potential as a pan-shigella vaccine.shigellosis is an important disease in the developing world, where about 90 million people become infected with shigella spp. each year. we previously demonstrated that the type three secretion apparatus (t3sa) proteins ipab and ipad are protective antigens in the mouse lethal pulmonary model. in order to simplify vaccine formulation and process development, we have evaluated a vaccine design that incorporates both of these previously tested shigella antigens into a single polypeptide chain. to ...201324060976
synthesis of some novel bis[1, 2, 4]triazolo[3, 4-b][1, 3, 4]thiadiazine derivatives for antimicrobial evaluation.a new series of novel bis[1, 2, 4]triazolo[3, 4-b][1, 3, 4]thiadiazines 7a-j has been synthesized by the reaction of [5, 5'-methylenebis(3-methylbenzofuran-7, 5-diyl)]bis[(4-amino-5-thioxo-4, 5-dihydro-1h-1, 2, 4-triazol-3-yl)methanone] (6) with a variety of phenacyl bromides in ethanol under reflux for 6 h. all the newly synthesized compounds were tested for in vitro activity against certain strains of bacteria such as escherichia coli, klebsiella pneumoniae, shigella dysenteriae and shigella f ...201124062120
impact of reclaimed water irrigation on antibiotic resistance in public parks, beijing, china.the abundance and distribution of antibiotics and antibiotic resistance genes (args) in soils from six parks using reclaimed water in beijing, china, were characterized. three classes of commonly used antibiotics (tetracycles, quinolones, and sulfonamides) were analyzed by liquid chromatography-tandem mass spectrometry (lc-ms/ms). the highest concentrations of tetracyclines and quinolones were 145.2 μg kg(-1) and 79.2 μg kg(-1), respectively. detected tetg, tetw, suli, and sulii genes were quant ...201424071635
production of microbial medium from defatted brebra (milletia ferruginea) seed flour to substitute commercial peptone agar.to investigate and optimize microbial media that substitute peptone agar using brebra seed defatted flour.201324075344
role of porin proteins in acquisition of transferrin iron by enteropathogens.acquisition of iron from key innate immune defence proteins such as transferrin (tf) and lactoferrin is an important mechanism by which pathogenic bacteria obtain essential iron for growth within their host. bacterial species that do not produce siderophores often use specific tf-binding proteins, the best characterized being the neisseriaceae-type tf-binding proteins tbpa and tbpb. previous work from our laboratory has shown that siderophore-producing enteric species such as escherichia coli al ...201324089578
isolation, characterization and comparative genomics of bacteriophage sfiv: a novel serotype converting phage from shigella flexneri.shigella flexneri is the major cause of shigellosis in the developing countries. the o-antigen component of the lipopolysaccharide is one of the key virulence determinants required for the pathogenesis of s. flexneri. the glucosyltransferase and/or acetyltransferase genes responsible for the modification of the o-antigen are encoded by temperate serotype converting bacteriophage present in the s. flexneri genome. several serotype converting phages have previously been isolated and characterized, ...201324090466
[ctx-m-type extended-spectrum β-lactamase in shigella flexneri isolates from pediatric patients with acute diarrhea]. 201324100837
analysis of the proteome of intracellular shigella flexneri reveals pathways important for intracellular growth.global proteomic analysis was performed with shigella flexneri strain 2457t in association with three distinct growth environments: s. flexneri growing in broth (in vitro), s. flexneri growing within epithelial cell cytoplasm (intracellular), and s. flexneri that were cultured with, but did not invade, henle cells (extracellular). compared to in vitro and extracellular bacteria, intracellular bacteria had increased levels of proteins required for invasion and cell-to-cell spread, including ipa, ...201324101689
an alternative outer membrane secretion mechanism for an autotransporter protein lacking a c-terminal stable core.autotransporter (at) proteins are a broad class of virulence factors from gram-negative pathogens. at outer membrane (om) secretion appears simple in many regards, yet the mechanism that enables transport of the central at 'passenger' across the om remains unclear. om secretion efficiency for two at passengers is enhanced by approximately 20 kda stable core at the c-terminus of the passenger, but studies on a broader range of at proteins are needed in order to determine whether a stability diffe ...201324118465
spa13 of shigella flexneri has a dual role: chaperone escort and export gate-activator switch of the type iii secretion system.the type iii secretion apparatus (t3sa) is used by numerous gram-negative pathogens to inject virulence factors into eukaryotic cells. the shigella flexneri t3sa spans the bacterial envelope and its assembly requires the products of ~20 mxi and spa genes. despite progress made in understanding how the t3sa is assembled, the role of several predicted soluble components, such as spa13, remains elusive. here, we show that the secretion defect of the spa13 mutant is associated with lack of t3sa asse ...201424126350
mait cells detect and efficiently lyse bacterially-infected epithelial cells.mucosal associated invariant t cells (mait) are innate t lymphocytes that detect a large variety of bacteria and yeasts. this recognition depends on the detection of microbial compounds presented by the evolutionarily conserved major-histocompatibility-complex (mhc) class i molecule, mr1. here we show that mait cells display cytotoxic activity towards mr1 overexpressing non-hematopoietic cells cocultured with bacteria. the nk receptor, cd161, highly expressed by mait cells, modulated the cytokin ...201324130485
a contribution of mdfa to resistance to fluoroquinolones in shigella flexneri.in this study, we measured the drug resistance conferred by mdfa mutations in two shigella flexneri strains. a mutant in mdfa genes was constructed by polymerase chain reaction-based, one-step inactivation of chromosomal genes. the antimicrobial susceptibility of parent and mutant strains to fluoroquinolones was determined by minimal inhibitory concentration (mics). the △mdfa mutants were somewhat more susceptible to fluoroquinolones than the parent strains. the low level changes in mics of the ...201124159476
enhanced type iii secretion system expression of atypical shigella flexneri ii:(3)4,7(8).we aimed at evaluating the virulence of atypical shigella flexneri ii:(3)4,7(8) by dna microarray and invasion assay.201224159518
epidemiological characteristics of imported shigellosis in korea, 2010-2011.shigellosis is a global disease as food poisoning by infection of shigella spp (s. dysenteriae, s. flexneri, s. boydii and s. sonnei). in korea, approximately 500 cases of shigellosis have reported every year since 2004, and imported shigellosis is increasing gradually from 2006 in particular. according to increase of numbers of overseas travelers, the numbers of patients diseased with imported shigellosis is also increasing. we need continuous surveillance studies network (ssn) for control of i ...201324159548
intracellular shigella remodels its lps to dampen the innate immune recognition and evade inflammasome activation.lps is a potent bacterial effector triggering the activation of the innate immune system following binding with the complex cd14, myeloid differentiation protein 2, and toll-like receptor 4. the lps of the enteropathogen shigella flexneri is a hexa-acylated isoform possessing an optimal inflammatory activity. symptoms of shigellosis are produced by severe inflammation caused by the invasion process of shigella in colonic and rectal mucosa. here we addressed the question of the role played by the ...201324167293
a creb3-arf4 signalling pathway mediates the response to golgi stress and susceptibility to pathogens.treatment of cells with brefeldin a (bfa) blocks secretory vesicle transport and causes a collapse of the golgi apparatus. to gain more insight into the cellular mechanisms mediating bfa toxicity, we conducted a genome-wide haploid genetic screen that led to the identification of the small g protein adp-ribosylation factor 4 (arf4). arf4 depletion preserves viability, golgi integrity and cargo trafficking in the presence of bfa, and these effects depend on the guanine nucleotide exchange factor ...201324185178
transposition of isecp1 modulates blactx-m-55-mediated shigella flexneri resistance to cefalothin.the aim of this study was to uncover the mechanisms underlying shigella flexneri resistance to cefalothin. in this study, a resistance-related s. flexneri isolate, s. flexneri ydc, was obtained from s. flexneri mel-1998023/zz pre-incubated with cefalothin at a dose of 0.5 × the minimum inhibitory concentration. the isecp1 coding element was identified upstream of bla(ctx-m-55) in s. flexneri ydc. to further determine the role of isecp1 in s. flexneri resistance, plasmids containing bla(ctx-m-55) ...201324207017
n-terminus of ipab provides a potential anchor to the shigella type iii secretion system tip complex protein ipad.the type iii secretion system (t3ss) is an essential virulence factor for shigella flexneri , providing a conduit through which host-altering effectors are injected directly into a host cell to promote uptake. the type iii secretion apparatus (t3sa) is composed of a basal body, external needle, and regulatory tip complex. the nascent needle is a polymer of mxih capped by a pentamer of invasion plasmid antigen d (ipad). exposure to bile salts (e.g., deoxycholate) causes a conformational change in ...201324236510
isolation and molecular characterization of salmonella enterica, escherichia coli o157:h7 and shigella spp. from meat and dairy products in egypt.foodborne pathogens are a major threat to food safety, especially in developing countries where hygiene and sanitation facilities are often poor. salmonella enterica, escherichia coli o157:h7 and shigella spp. are among the major causes of outbreaks of foodborne diseases. this large-scale study investigated the prevalence of these foodborne pathogens in meat (beef and chicken) and dairy products collected from street vendors, butchers, retail markets and slaughterhouses in egypt. a total of 1600 ...201424239976
the host and the flora.to prevent bacterial overgrowth, colonization of the epithelium and subsequent translocation, the gastrointestinal tract maintains an effective mucosal barrier. besides mucus the most important components of this protective system are epithelial antimicrobial peptides such as defensins, the cathelicidin ll-37, lysozyme, phospholipase a, and proteins with additional antimicrobial properties such as ubiquicidin, ribosomal proteins or histones. commensal species may tolerate intestinal antimicrobia ...201324246976
[o-antigen modification and serotype conversion of shigella flexneri]. 201324257184
characterization of extended-spectrum beta-lactamase-producing clinical isolates of shigella flexneri. 201324288956
subversion of inflammasome activation and pyroptosis by pathogenic bacteria.activation of the inflammasome occurs in response to a notably high number of pathogenic microbes and is a broad innate immune response that effectively contributes to restriction of pathogen replication and generation of adaptive immunity. activation of these platforms leads to caspase-1- and/or caspase-11-dependent secretion of proteins, including cytokines, and induction of a specific form of cell death called pyroptosis, which directly or indirectly contribute for restriction of pathogen rep ...201324324933
temperature-regulated expression of outer membrane proteins in shigella flexneri.bacteria exist widely in a diversity of natural environments. in order to survive adverse conditions such as nutrient depletion, biochemical and biological disturbances, and high temperature, bacteria have developed a wide variety of coping mechanisms. temperature is one of the most important factors that can enhance the expression of microbial proteins. this study was conducted to investigate how outer membrane proteins (omps) of the bacterium shigella flexneri respond to stress, especially dur ...201324330657
a shigella effector dampens inflammation by regulating epithelial release of danger signal atp through production of the lipid mediator ptdins5p.upon infection with shigella flexneri, epithelial cells release atp through connexin hemichannels. however, the pathophysiological consequence and the regulation of this process are unclear. here we showed that in intestinal epithelial cell atp release was an early alert response to infection with enteric pathogens that eventually promoted inflammation of the gut. shigella evolved to escape this inflammatory reaction by its type iii secretion effector ipgd, which blocked hemichannels via the pro ...201324332032
impact of dynasore an inhibitor of dynamin ii on shigella flexneri infection.shigella flexneri remains a significant human pathogen due to high morbidity among children < 5 years in developing countries. one of the key features of shigella infection is the ability of the bacterium to initiate actin tail polymerisation to disseminate into neighbouring cells. dynamin ii is associated with the old pole of the bacteria that is associated with f-actin tail formation. dynamin ii inhibition with dynasore as well as sirna knockdown significantly reduced shigella cell to cell spr ...201324367704
cgtase-catalysed cis-glucosylation of l-rhamnosides for the preparation of shigella flexneri 2a and 3a haptens.we report the enzymatic synthesis of α-d-glucopyranosyl-(1→4)-α-l-rhamnopyranoside and α-d-glucopyranosyl-(1→3)-α-l-rhamnopyranoside by using a wild-type transglucosidase in combination with glucoamylase and glucose oxidase. it was shown that bacillus circulans 251 cyclodextrin glucanotransferase (cgtase, ec 2.1.4.19) can efficiently couple an α-l-rhamnosyl acceptor to a maltodextrin molecule with an α-(1→4) linkage, albeit in mixture with the α-(1→3) regioisomer, thus giving two glucosylated ac ...201424376024
dissemination and serotype modification potential of psfxv_2, an o-antigen petn modification plasmid in shigella flexneri.the o-antigens of all shigella flexneri serotypes, except serotype 6, share a linear tetrasaccharide repeat composed of one n-acetylglucosamine and three l-rhamnose residues, and differences between the serotypes are due to modification of various monosaccharide residues with glucosyl and/or o-acetyl and/or phosphoethanolamine (petn) groups. plasmid-borne opt (formerly lpt-o) gene encoding a petn transferase which modifies the o-antigens of s. flexneri serotype x, 4a and y strains and converts t ...201424379081
development and preclinical evaluation of a trivalent, formalin-inactivated shigella whole-cell vaccine.studies were undertaken to manufacture a multivalent shigella inactivated whole-cell vaccine that is safe, effective, and inexpensive. by using several formalin concentrations, temperatures, and incubation periods, an optimized set of inactivation conditions was established for shigella flexneri 2a, s. sonnei, and s. flexneri 3a to produce inactivated whole cells expressing a full repertoire of ipa proteins and lipopolysaccharide (lps). the inactivation conditions selected were treatment with 0. ...201424403527
effect of wild-type shigella species and attenuated shigella vaccine candidates on small intestinal barrier function, antigen trafficking, and cytokine release.bacterial dysentery due to shigella species is a major cause of morbidity and mortality worldwide. the pathogenesis of shigella is based on the bacteria's ability to invade and replicate within the colonic epithelium, resulting in severe intestinal inflammatory response and epithelial destruction. although the mechanisms of pathogenesis of shigella in the colon have been extensively studied, little is known on the effect of wild-type shigella on the small intestine and the role of the host respo ...201424416363
plasmid-mediated sulfamethoxazole resistance encoded by the sul2 gene in the multidrug-resistant shigella flexneri 2a isolated from patients with acute diarrhea in dhaka, bangladesh.in this study, mechanisms of plasmid-mediated sulfamethoxazole resistances in the clinical strains of multi-drug resistant (mdr) shigella flexneri 2a were elucidated for the first time in bangladesh. from 2006 to 2011, a total of 200 s. flexneri 2a strains were randomly selected from the stock of the enteric and food microbiology laboratory of icddr,b. antimicrobial susceptibility of the strains showed 73%, 98%, 93%, 58%, 98%, 64% and 4% resistance to trimethoprim-sulfamethoxazole, nalidixic aci ...201424416393
ph and acidity in lactic-fermenting cereal gruels: effects on viability of enteropathogenic microorganisms.survival of bacillus cereus, campylobacter jejuni, enterotoxigenic escherichia coli, salmonella typhimurium and shigella flexneri during lactic acid fermentation of cereal gruels prepared from low-tannin (white) and high-tannin (red) sorghum varieties was studied. a previously fermented gruel (starter culture, sc) recycled daily or stored for 7, 14 or 28 days, germinated cereal flour (power flour, pf), or a combination of pf and sc (pf+sc) were used as starters. at 24 h, the ph of all gruels wit ...199424421191
inhibited growth of common enteropathogenic bacteria in lactic-fermented cereal gruels.a natural lactic fermentation of mixtures of water and whole flour of either maize or high-tannin sorghum was obtained either before or after cooking to a weaning gruel: the preparations had a final ph of about 3.8 (range 3.67 to 4.00) and a ratio of lactic acid to acetic acid of 9∶1 (w/w). the growth of added (about 10(7) c.f.u./g gruel) gram-negative intestinal pathogenic bacteria, enterotoxigenicescherichia coli, campylobacter jejuni, shigella flexneri andsalmonella typhimurium, was strongly ...199224425608
relationship between o-antigen chain length and resistance to colicin e2 in shigella flexneri.the shigella flexneri polysaccharide co-polymerase class 1a (pcp1a) protein, wzzbsf, regulates lps o-antigen (oag) chain length to confer short (s)-type oag chains of ~10-17 oag repeat units (rus). the s-type oag chains affect shigella flexneri virulence as they influence icsa-mediated actin-based motility. however, they do not confer resistance to complement; this is conferred by the very-long (vl)-type oag chains determined by wzzb(phs2). colicins are bacterial proteins produced by some escher ...201424425769
genomic portrait of the evolution and epidemic spread of a recently emerged multidrug-resistant shigella flexneri clone in china.shigella flexneri is the major cause of shigellosis in developing countries. a new s. flexneri serotype, xv, appeared in 2000 and replaced serotype 2a as the most prevalent serotype in china. serotype xv is a variant of serotype x, with phosphoethanolamine modification of its o antigen mediated by a plasmid that contained the opt gene. serotype xv isolates belong to sequence type 91 (st91). in this study, whole-genome sequencing of 59 s. flexneri isolates of 14 serotypes (serotypes 1 to 4, y, yv ...201424452172
intradermal delivery of shigella ipab and ipad type iii secretion proteins: kinetics of cell recruitment and antigen uptake, mucosal and systemic immunity, and protection across serotypes.shigella is one of the leading pathogens contributing to the vast pediatric diarrheal disease burden in low-income countries. no licensed vaccine is available, and the existing candidates are only partially effective and serotype specific. shigella type iii secretion system proteins ipab and ipad, which are conserved across shigella spp., are candidates for a broadly protective, subunit-based vaccine. in this study, we investigated the immunogenicity and protective efficacy of ipab and ipad admi ...201424453241
electron tomography and simulation of baculovirus actin comet tails support a tethered filament model of pathogen propulsion.several pathogens induce propulsive actin comet tails in cells they invade to disseminate their infection. they achieve this by recruiting factors for actin nucleation, the arp2/3 complex, and polymerization regulators from the host cytoplasm. owing to limited information on the structural organization of actin comets and in particular the spatial arrangement of filaments engaged in propulsion, the underlying mechanism of pathogen movement is currently speculative and controversial. using electr ...201424453943
a substrate-fusion protein is trapped inside the type iii secretion system channel in shigella flexneri.the type iii secretion system (t3ss) is a macromolecular complex used by gram-negative bacteria to secrete effector proteins from the cytoplasm across the bacterial envelope in a single step. for many pathogens, the t3ss is an essential virulence factor that enables the bacteria to interact with and manipulate their respective host. a characteristic structural feature of the t3ss is the needle complex (nc). the nc resembles a syringe with a basal body spanning both bacterial membranes and a long ...201424453973
age-dependent association among helicobacter pylori infection, serum pepsinogen levels and immune response of children to live oral cholera vaccine cvd 103-hgr.through its effects on gastric secretion, we hypothesized that helicobacter pylori infection may influence oral immunization. accordingly, we examined the association between h. pylori infection, serum pepsinogen (pg) (measures for h. pylori gastritis) and vibriocidal antibody (a correlate of protection) seroconversion following oral immunization with cvd 103-hgr live cholera vaccine among children of different ages.201424454714
a gene knock-in method used to purify plasmid pspi12 from salmonella enterica serovar pullorum and characterization of ipaj.a small plasmid with 4080 bp long, designated pspi12, was purified from salmonella enterica serovar pullorum using a gene knock-in method by inserting a kanamycin resistance cassette in the plasmid. the g+c content of the plasmid was 51.8%, which is in the range of salmonella genomic dna. a sequence analysis revealed that pspi12 had 99.1% homology to psfd10, which was first reported in the vaccine strain s. enterica serovar chloreaesuis c500, but not prevalent among other strains of s. chloreaes ...201424468333
eata, an immunogenic protective antigen of enterotoxigenic escherichia coli, degrades intestinal mucin.enterotoxigenic escherichia coli (etec) is a major cause of morbidity and mortality due to infectious diarrhea in developing countries for which there is presently no effective vaccine. a central challenge in etec vaccinology has been the identification of conserved surface antigens to formulate a broadly protective vaccine. here, we demonstrate that eata, an immunogenic secreted serine protease of etec, contributes to virulence by degrading muc2, the major protein present in the small intestina ...201324478066
the vps/vacj abc transporter is required for intercellular spread of shigella flexneri.the vps/vacj abc transporter system is proposed to function in maintaining the lipid asymmetry of the outer membrane. mutations in vps or vacj in shigella flexneri resulted in increased sensitivity to lysis by the detergent sodium dodecyl sulfate (sds), and the vpsc mutant showed minor differences in its phospholipid profile compared to the wild type. vpsc mutants were unable to form plaques in cultured epithelial cells, but this was not due to a failure to invade, to replicate intracellularly, ...201424478081
case of shigella flexneri infection with treatment failure due to azithromycin resistance in an hiv-positive patient. 201424488332
multiplex pcr (polymerase chain reaction) assay for detection of e. coli o157:h7, salmonella sp., vibrio cholerae and vibrio parahaemolyticus in spiked shrimps (penaeus monodon).the coastal aquaculture mainly shrimps constitute major export sector in bangladesh and is increasingly shaped by international trade conditions and by national responses to those stringent quality and safety standards. pcr based validated methods for detection of major bacterial pathogens in shrimp might be very useful tool for ensuring quality and safety standards of exportable shrimps. the objective of this study was to evaluate overall performance (sensitivity and specificity) of the multipl ...201324498789
identification of an o-acyltransferase gene (oacb) that mediates 3- and 4-o-acetylation of rhamnose iii in shigella flexneri o antigens.o antigen (o polysaccharide) is an important and highly variable cell component present on the surface of cells which defines the serospecificity of gram-negative bacteria. most o antigens of shigella flexneri, a cause of shigellosis, share a backbone composed of →2)-α-l-rhap(iii)-(1→2)-α-l-rhap(ii)-(1→3)-α-l-rhap(i)-(1→3)-β-d-glcpnac-(1→ repeats, which can be modified by adding various substituents, giving rise to 19 serotypes. the known modifications include glucosylation on various sugar resi ...201424509314
shigellemia in a post renal transplant patient: a case report and literature review.shigellemia is a complication of shigellosis that occurs generally in malnourished children. in adults, shigellemia is usually seen in immunocompromised individuals. here we report the first case of shigellemia in a renal transplant patient from india. the patient had history of diarrhea, which was treated symptomatically. subsequently, the patient developed high-grade fever and blood culture was positive for shigella flexneri. recovery was uneventful after the initiation of antimicrobial therap ...201424518636
oral administration of live shigella vaccine candidates in rhesus monkeys show no evidence of competition for colonization and immunogenicity between different serotypes.live oral monovalent shigella flexneri 2a vaccine candidates as well as bivalent formulations with shigella sonnei were evaluated in a rhesus monkey model for colonization and immunogenicity. freshly harvested suspensions of s. flexneri 2a vaccine candidates wrsf2g12 and wrsf2g15 as well as s. sonnei vaccine candidate wrss3 were nasogastrically administered to groups of rhesus monkeys, macaca mulatta, either in a monovalent form or when combined with each other. the animals were monitored daily ...201424522159
plantaricin ld1: a bacteriocin produced by food isolate of lactobacillus plantarum ld1.plantaricin ld1, a bacteriocin produced by lactobacillus plantarum ld1, was characterized for biochemical and antimicrobial properties. bacteriocin showed stability at high temperatures (100 °c for 20 min and 121 °c for 15 min under 15 psi pressure), in a ph range of 2.0-8.0 and also in the presence of organic solvents, surfactants and detergents. the crude preparation was not affected by catalase, amylase and lipase but activity was reduced in the presence of pepsin, trypsin and proteinase k sh ...201424522411
a fluorescent reporter reveals on/off regulation of the shigella type iii secretion apparatus during entry and cell-to-cell spread.numerous pathogenic gram-negative bacteria use a type three secretion apparatus (t3sa) to translocate effector proteins into host cells. detecting and monitoring the t3sa of intracellular bacteria within intact host cells has been challenging. taking advantage of the tight coupling between t3s effector-gene transcription and t3sa activity in shigella flexneri, together with a fast-maturing green fluorescent protein, we developed reporters to monitor t3sa activity in real time. these reporters re ...201424528864
[data on biological characteristics of shigella flexneri]. 195324543445
[result of serological studies of standard cultures of shigella flexneri obtained from various museum collections]. 195324543446
[stability of changed properties of streptomycin-resistant strain of shigella flexneri after prolonged preservation]. 201424544446
potential novel antibiotics from hts targeting the virulence-regulating transcription factor, virf, from shigella flexneri.virf is an arac-type transcriptional regulator responsible for activating the transcription of virulence genes required for the intracellular invasion and cell-to-cell spread of shigella flexneri. gene disruption studies have validated virf as a potential target for an anti-virulence therapy to treat shigellosis by determining that virf is necessary for virulence, but not required for bacterial viability. using a bacteria-based, β-galactosidase reporter assay we completed a high-throughput scree ...201424549153
conformational diversity of o-antigen polysaccharides of the gram-negative bacterium shigella flexneri serotype y.o-antigen polysaccharides constitute the outer protective layer of most gram-negative bacteria, important for the bacterium's survival and adaption within its host. although important for many functions, the three-dimensional structure of the dense polysaccharide coat remains to be elucidated. in this study, we present a systematic numerical investigation of o-antigen polysaccharide chains of shigella flexneri serotype y composed of one up to four tetrasaccharide repeat units. to bridge the gap ...201424559142
synthesis, structures, spectroscopy and antimicrobial properties of complexes of copper(ii) with salicylaldehyde n-substituted thiosemicarbazones and 2,2'-bipyridine or 1,10-phenanthroline.among the biometals (cu, co, ni-cofactors in many enzymes), copper derivatives of o, n, s-donor salicylaldehyde thiosemicarbazones have received considerable attention owing to their potential biological applications. eight new complexes of salicylaldehyde-n-substituted thiosemicarbazones [5-meo-2-ho-c₆h₄-c(2)(h)n(3)-n(2)h-c(1)(s)-n(1)hr; r = me, h2l(1); et, h₂l(1), ph, h₂l(3), h, h₂l(4)] with copper(ii), namely, [cu(κ(3)-o,n,s-l)( κ(2)-n,n-l')] {(l)(2-) = (l(1))(2-), l' = bipy, 1, phen, 2; (l)( ...201424583354
polar localization of phon2, a periplasmic virulence-associated factor of shigella flexneri, is required for proper icsa exposition at the old bacterial pole.proper protein localization is critical for bacterial virulence. phon2 is a virulence-associated atp-diphosphohydrolase (apyrase) involved in icsa-mediated actin-based motility of s. flexneri. herein, by analyzing a δphon2 mutant of the s. flexneri strain m90t and by generating phon2::ha fusions, we show that phon2, is a periplasmic protein that strictly localizes at the bacterial poles, with a strong preference for the old pole, the pole where icsa is exposed, and that it is required for proper ...201424587292
development of an aotus nancymaae model for shigella vaccine immunogenicity and efficacy studies.several animal models exist to evaluate the immunogenicity and protective efficacy of candidate shigella vaccines. the two most widely used nonprimate models for vaccine development include a murine pulmonary challenge model and a guinea pig keratoconjunctivitis model. nonhuman primate models exhibit clinical features and gross and microscopic colonic lesions that mimic those induced in human shigellosis. challenge models for enterotoxigenic escherichia coli (etec) and campylobacter spp. have be ...201424595138
new insights into the crosstalk between shigella and t lymphocytes.subversion of host immune responses is the key infection strategy employed by most, if not all, human pathogens. modulation of the host innate response by pathogens has been vastly documented. yet, especially for bacterial infections, it was only recently that cells of the adaptive immune response were recognized as targets of bacterial weapons such as the type iii secretion system (t3ss) and its effector proteins. in this review, we focus on the recent advances made in the understanding of how ...201424613405
rabbit monoclonal antibodies directed at the t3ss effector protein yopm identify human pathogenic yersinia isolates.the yersinia outer protein m (yopm) is a type 3 secretion system (t3ss)-dependent effector protein of yersinia enterocolitica, yersinia pseudotuberculosis and yersinia pestis. although yopm is indispensable for full virulence, its molecular functions still remain largely elusive. recently, we could identify the recombinant yopm (ryopm) protein derived from the y. enterocolitica strain 8081 (jb580) as a cell-penetrating protein, which down-regulates the expression of various pro-inflammatory cyto ...201424636859
tyrosine kinases, drugs, and shigella flexneri dissemination.shigella flexneri is an enteropathogenic bacterium responsible for approximately 100 million cases of severe dysentery each year. s. flexneri colonization of the human colonic epithelium is supported by direct spread from cell to cell, which relies on actin-based motility. we have recently uncovered that, in intestinal epithelial cells, s. flexneri actin-based motility is regulated by the bruton's tyrosine kinase (btk). consequently, treatment with ibrutinib, a specific btk inhibitor currently u ...201724637806
serological identification and prevalence of a novel o-antigen epitope linked to 3- and 4-o-acetylated rhamnose iii of lipopolysaccharide in shigella flexneri.shigella flexneri is the major cause of shigellosis in developing countries. all serotypes except for serotype 6 share an o-antigen backbone composed of a → 2)-α-l-rhap(iii)-(1 → 2)-α-l-rhap(ii)-(1 → 3)-α-l-rhap(i)-(1 → 3)-β-d-glcpnac-(1 → tetrasaccharide repeat. it can be modified by the addition of a glucosyl group to one or more sugar residues and/or an o-acetyl group to rha(i) and/or a phosphoethanolamine to rha(ii) and/or rha(iii). these modifications give rise to type i-, ic-, ii-, iv-, an ...201424671799
ompa and ompc are critical host factors for bacteriophage sf6 entry in shigella.despite being essential for successful infection, the molecular cues involved in host recognition and genome transfer of viruses are not completely understood. bacterial outer membrane proteins a and c co-purify in lipid vesicles with bacteriophage sf6, implicating both outer membrane proteins as potential host receptors. we determined that outer membrane proteins a and c mediate sf6 infection by dramatically increasing its rate and efficiency. we performed a combination of in vivo studies with ...201424673644
probiotic potential of lactobacillus plantarum ld1 isolated from batter of dosa, a south indian fermented food.lactobacillus plantarum ld1 was isolated from dosa batter and identified by biochemical, physiological and genetic methods. species level identification was done by 16s rdna amplification and sequencing. the probiotic potential of strain ld1 was assessed by different standard parameters. cell surface hydrophobicity was recorded to be 62% with sat value <0.007 m. seventy-eight percent of viable count was found after treatment with simulated gastric juice containing pepsin (ph 2.0). bile salt tole ...201424676724
draft genome sequences of the type strains of shigella flexneri held at public health england: comparison of classical phenotypic and novel molecular assays with whole genome sequence.public health england (phe) holds a collection of shigella flexneri type strains isolated between 1949 and 1972 representing 15 established serotypes and one provisional type, e1037. in this study, the genomes of all 16 phe type strains were sequenced using the illumina hiseq platform. the relationship between core genome phylogeny and serotype was examined.201424684748
[preparation and identification of the polyclonal antibody against gapdh protein from shigella flexneri m90t].to prepare mouse polyclonal antibodies against shigella flexneri m90t glyceraldehyde-3-phosphate dehydrogenase (gapdh), and verify its titer and specificity.201424721410
icsa is a shigella flexneri adhesin regulated by the type iii secretion system and required for pathogenesis.following contact with the epithelium, the enteric intracellular bacterial pathogen shigella flexneri invades epithelial cells and escapes intracellular phagosomal destruction using its type iii secretion system (t3ss). the bacterium replicates within the host cell cytosol and spreads between cells using actin-based motility, which is mediated by the virulence factor icsa (virg). whereas s. flexneri invasion is well characterized, adhesion mechanisms of the bacterium remain elusive. we found tha ...201424721572
murine solid tumours as a novel model to study bacterial biofilm formation in vivo.bacteria of many species are able to invade and colonize solid tumours in mice. we have focused on salmonella enterica serovar typhimurium. detailed analysis revealed that such tumour-invading salmonella form biofilms, thus providing a versatile in vivo test system for studying bacterial phenotypes and host-pathogen interactions. it appears that biofilm formation by s. typhimurium is induced as a defence against the immune system of the host, and in particular against neutrophils. further, we ex ...201424724621
role of intracellular carbon metabolism pathways in shigella flexneri virulence.shigella flexneri, which replicates in the cytoplasm of intestinal epithelial cells, can use the embden-meyerhof-parnas, entner-doudoroff, or pentose phosphate pathway for glycolytic carbon metabolism. to determine which of these pathways is used by intracellular s. flexneri, mutants were constructed and tested in a plaque assay for the ability to invade, replicate intracellularly, and spread to adjacent epithelial cells. mutants blocked in the embden-meyerhof-parnas pathway (pfkab and pykaf mut ...201424733092
dynamin-related protein drp1 and mitochondria are important for shigella flexneri infection.shigella infection in epithelial cells induces cell death which is accompanied by mitochondrial dysfunction. in this study the role of the mitochondrial fission protein, drp1 during shigella infection in hela cells was examined. significant lactate dehydrogenase (ldh) release was detected in the culture supernatant when hela cells were infected with shigella at a high multiplicity of infection. drp1 inhibition with mdivi-1 and sirna knockdown significantly reduced ldh release. hela cell death wa ...201424755420
the periplasmic enzyme, ansb, of shigella flexneri modulates bacterial adherence to host epithelial cells.s. flexneri strains, most frequently linked with endemic outbreaks of shigellosis, invade the colonic and rectal epithelium of their host and cause severe tissue damage. here we have attempted to elucidate the contribution of the periplasmic enzyme, l-asparaginase (ansb) to the pathogenesis of s. flexneri. using a reverse genetic approach we found that ansb mutants showed reduced adherence to epithelial cells in vitro and attenuation in two in vivo models of shigellosis, the caenorhabditis elega ...201424762742
genetic characterization of shigella spp. isolated from diarrhoeal and asymptomatic children.phenotypic and genetic characteristics of shigella spp. isolated from diarrhoeal and asymptomatic children aged up to 5 years were analysed in this study. in total, 91 and 17 isolates were identified from diarrhoeal (case) and asymptomatic (control) children, respectively. all the isolates were tested for antimicrobial resistance, the presence of integrons, plasmid-mediated quinolone resistance (pmqr), virulence-associated genes and shigella pathogenicity island (sh-pai). the majority of the shi ...201424790083
decay of genetic markers for fecal bacterial indicators and pathogens in sand from lake superior.beach sands impact water quality and pathogen loads, however, the comparative decay of the fecal indicator bacteria (fib) enterococcus spp. and escherichia coli, and pathogens in freshwater sand have not been examined. in this study, freshwater sand microcosms were inoculated with sewage and pure cultures of bacterial pathogens to compare relative decay rates. the abundance of culturable enterococcus spp. and e. coli, genetic markers for enterococcus spp. (entero1), total bacteroides (allbac), a ...201424793108
ntrbc and nac contribute to efficient shigella flexneri intracellular replication.shigella flexneri two-component regulatory systems (tcrs) are responsible for sensing changes in environmental conditions and regulating gene expression accordingly. we examined 12 tcrs that were previously uncharacterized for potential roles in s. flexneri growth within the eukaryotic intracellular environment. we demonstrate that the tcrs evgsa, ntrbc, and rstba systems are required for wild-type plaque formation in cultured epithelial cells. the phenotype of the ntrbc mutant depended in part ...201424794563
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