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differential regulation of caspase-1 activation, pyroptosis, and autophagy via ipaf and asc in shigella-infected macrophages.shigella infection, the cause of bacillary dysentery, induces caspase-1 activation and cell death in macrophages, but the precise mechanisms of this activation remain poorly understood. we demonstrate here that caspase-1 activation and il-1beta processing induced by shigella are mediated through ipaf, a cytosolic pattern-recognition receptor of the nucleotide-binding oligomerization domain (nod)-like receptor (nlr) family, and the adaptor protein apoptosis-associated speck-like protein containin ...200717696608
omptin proteins: an expanding family of outer membrane proteases in gram-negative enterobacteriaceae.the escherichia coli k-12 outer membrane protein ompt is a prototype of a unique family of bacterial endopeptidases known as the omptins. this family includes ompt and ompp of e. coli, sopa of shigella flexneri, pgte of salmonella enterica, and pla of yersinia pestis. despite their sequence similarities, the omptins vary in their reported functions. the ompt protease is characterized by narrow cleavage specificity defined by the extracellular loops of the beta-barrel protruding above the lipid b ...200717710644
spontaneous zygogenesis, a wide-ranging mating process in bacteria.spontaneous zygogenesis (or z-mating) in escherichia coli, unlike f-mediated conjugation, promotes formation of complete zygotes. most z-mating products have proven to be phenotypically unstable, losing part of the phenotype for which they were selected. persistent z-mating products appear as stable genetic recombinants or yield subclones of two types: either both parental types or one of them plus a recombinant type, and the ability to promote spontaneous zygogenesis can appear in all emerging ...200717720456
an inducible lambdoid prophage encoding cytolethal distending toxin (cdt-i) and a type iii effector protein in enteropathogenic escherichia coli.cytolethal distending toxins (cdts) are inhibitory cyclomodulins, which block eukaryotic cell proliferation and are produced by a diverse group of gram-negative bacteria, including escherichia coli strains associated with intestinal and extraintestinal infections. however, the mode of transmission of the toxin gene clusters among diverse bacterial pathogens is unclear. we found that cdt-i produced by enteropathogenic e. coli strains associated with diarrhea is encoded by a lambdoid prophage, whi ...200717726095
intracellular type iii secretion by cytoplasmic shigella flexneri promotes caspase-1-dependent macrophage cell death.the gram-negative bacterium shigella flexneri triggers pro-inflammatory apoptotic cell death in macrophages, which is crucial for the onset of an acute inflammatory diarrhoea termed bacillary dysentery. the mxi-spa type iii secretion system promotes bacterial uptake and escape into the cytoplasm, where, dependent on the translocator/effector protein ipab, caspase-1 [interleukin (il)-1beta-converting enzyme] and its substrate il-1beta are activated. here, we show that in the course of a macrophag ...200717768231
[total and specific iga in colostrum and milk of mothers of natal-rio grande do norte, brasil].to determine the concentration of total secretory iga and evaluate the repertoire of iga antibodies to enteropathogenic escherichia coli and shigella flexneri antigens in colostrums and milk from mothers in natal, rn.200517768806
antibody response in man to injection of the specific antigen of type v shigella paradysenteriae. 194417772139
cross-species cluster co-conservation: a new method for generating protein interaction networks.co-conservation (phylogenetic profiles) is a well-established method for predicting functional relationships between proteins. several publicly available databases use this method and additional clustering strategies to develop networks of protein interactions (cluster co-conservation (ccc)). ccc has previously been limited to interactions within a single target species. we have extended ccc to develop protein interaction networks based on co-conservation between protein pairs across multiple sp ...200717803817
identification of the mxih needle protein residues responsible for anchoring invasion plasmid antigen d to the type iii secretion needle tip.the pathogenesis of shigella flexneri requires a functional type iii secretion apparatus to serve as a conduit for injecting host-altering effector proteins into the membrane and cytoplasm of the targeted cell. the type iii secretion apparatus is composed of a basal body and an exposed needle that is an extended polymer of mxih with a 2.0-nm inner channel. invasion plasmid antigen d (ipad) resides at the tip of the needle to control type iii secretion. the atomic structures of mxih and ipad have ...200717827155
transcriptional profile induced by furazolidone treatment of shigella flexneri.shigella flexneri is a facultative intracellular pathogen responsible for endemic shigellosis especially in developing countries. furazolidone, a nitrofuran derivative, is very effective against the infection with s. flexneri. to examine potential effects of furazolidone on this germ, a whole-genome dna microarray was constructed and transcriptional profiles of the responses to furazolidone were determined. the expressing data revealed adaptive responses of s. flexneri to oxidative stress induce ...200717851659
isolation and antibiotic susceptibility of salmonella and shigella strains isolated from children in gaza, palestine from 1999 to 2006.diarrhea and acute gastroenteritis are among the leading causes of illnesses and death in infants and children throughout the world, especially in developing countries, globally, salmonella and shigella remain the major contributors to acute enteric infections and diarrhea.200817854424
plasmid-mediated quinolone resistance conferred by qnrs1 in salmonella enterica serovar virchow isolated from turkish food of avian origin.to study the molecular characteristics of the quinolone and associated ampicillin resistance mechanisms present in salmonella enterica serovar virchow isolated from turkish foods.200717881633
dynamic proteome changes of shigella flexneri 2a during transition from exponential growth to stationary phase.shigella flexneri is an infectious pathogen that causes dysentery to human, which remains a serious threat to public health, particularly in developing countries. in this study, the global protein expression patterns of s. flexneri during transition from exponential growth to stationary phase in vitro were analyzed by using 2-d page combined with maldi-tof ms. in a time-course experiment with five time points, the relative abundance of 49 protein spots varied significantly. interestingly, a puta ...200717893076
the type iii secretion system of proteus mirabilis hi4320 does not contribute to virulence in the mouse model of ascending urinary tract infection.the gram-negative enteric bacterium proteus mirabilis is a frequent cause of urinary tract infections (utis) in individuals with long-term indwelling catheters or with complicated urinary tracts. the recent release of the p. mirabilis strain hi4320 genome sequence has facilitated identification of potential virulence factors in this organism. genes appearing to encode a type iii secretion system (ttss) were found in a low gc-content pathogenicity island in the p. mirabilis chromosome. this islan ...200717893161
o-antigen modal chain length in shigella flexneri 2a is growth-regulated through rfah-mediated transcriptional control of the wzy gene.shigella flexneri 2a 2457t produces lipopolysaccharide (lps) with two o-antigen (oag) chain lengths: a short (s-oag) controlled by wzzb and a very long (vl-oag) determined by wzz(phs-2). this study demonstrates that the synthesis and length distribution of the s. flexneri oag are under growth-phase-dependent regulation. quantitative electrophoretic analysis showed that the vl-oag increased during growth while the s-oag distribution remained constant. increased production of vl-oag correlated wit ...200717906147
identification of newly recognized serotype 1c as the most prevalent shigella flexneri serotype in northern rural vietnam.we investigated the identity of 37 shigella flexneri strains that had previously been isolated from northern rural vietnam (son tay province) and described as untypable. twenty-four isolates reacted with masf 1c, a monoclonal antibody specific for s. flexneri serotype 1c. a further ten untypable isolates were found to be rough mutants (no longer expressing o-antigen) that were derived from serotype 1c strains. pulsed-field gel electrophoresis demonstrated that these strains consisted of many dif ...200817922932
a role for nod-like receptors in autophagy induced by shigella infection.shigella infection, the cause of bacillary dysentery, induces caspase-1 activation and cell death in macrophages, but the precise mechanisms remain poorly understood. in our recent study, we presented evidence that caspase-1 activation and il-1beta processing induced by shigella are mediated through ipaf, a cytosolic pattern-recognition receptor of the nucleotide-binding oligomerization domain (nod)-like receptor (nlr) family and the adaptor protein apoptosis-associated speck-like protein contai ...200817932464
vinculin binding in its closed conformation by a helix addition mechanism.vinculin links integrin receptors to the actin cytoskeleton by binding to talin. vinculin is held in an inactive, closed-clamp conformation through hydrophobic interactions between its head and tail domains, and vinculin activation has long been thought to be dependent upon severing the head-tail interaction. talin, alpha-actinin, and the invasin ipaa of shigella flexneri sever vinculin's head-tail interaction by inserting an alpha-helix into vinculin's n-terminal four-helical bundle, provoking ...200717932491
safety and immunogenicity of cvd 1208s, a live, oral deltaguaba deltasen deltaset shigella flexneri 2a vaccine grown on animal-free media.a previous phase 1 trial demonstrated that shigella flexneri 2a deleted in guaba, sen and set (strain cvd 1208) is well-tolerated and immunogenic after a single oral dose of 10(8) or 10(9) cfu. to facilitate further clinical development, the strain was reconstructed using animal-free media to conform to regulatory guidelines, and designated cvd1208s. healthy inpatient volunteers were randomized (double-blind) to receive a single oral dose of either cvd 1208s (10(8) [n = 7] or 10(9) [n = 7] cfu) ...200717938573
transcription-termination-mediated immunity and its prevention in bacteriophage sfv of shigella flexneri.the temperate phage sfv encodes the genes responsible for the serotype conversion of shigella flexneri strains from serotype y to 5a. bacteriophages often encode proteins that prevent subsequent infection by homologous phages; the mechanism by which this is accomplished is referred to as superinfection immunity. the serotype conversion mediated following lysogenization of sfv is one such mechanism. another mechanism is the putative lambda-like ci protein within sfv. this study reports the charac ...200717947546
synthesis, characterization and antibacterial activity of cobalt(iii) complexes with pyridine-amide ligands.the ligands 2-(n-(x-pyridyl)carbamoyl)pyridine (x=2, 3 or 4 for hl1-hl3, respectively) and 2,6-bis(n-(y-pyridyl)carbamoyl)pyridine (y=2, 3 or 4 for h2l4-h2l6, respectively) in their mono- and di-deprotonated forms have been used to synthesize kinetically stable cobalt(iii) compounds [co(l1-3)3] (1-3) and na[co(l4-6)2] (4-6), respectively. the co(iii) ion is in octahedral environment and is surrounded by three bidentate ligands in complexes 1-3 and two tridentate ligands in complexes 4-6. ligands ...200817959275
crystal structure of an apo form of shigella flexneri arsh protein with an nadph-dependent fmn reductase activity.the arsh gene or its homologs are a frequent part of the arsenic resistance system in bacteria and eukaryotes. although a specific biological function of the gene product is unknown, the arsh protein was annotated as a member of the nadph-dependent fmn reductase family based on a conserved (t/s)xrxxsx(t/s) fingerprint motif common for fmn binding proteins. presented here are the first crystal structure of an arsh protein from shigella flexneri refined at 1.7 a resolution and results of enzymatic ...200717962405
multilocus sequence typing analysis of shigella flexneri isolates collected in asian countries.the multilocus sequence typing scheme used previously for phylogenetic analysis of escherichia coli was applied to 107 clinical isolates of shigella flexneri. dna sequencing of 3423 bp throughout seven housekeeping genes identified eight new allele types and ten new sequence types among the isolates. s. flexneri serotypes 1-5, x and y were clustered together in a group containing many allelic variants while serotype 6 formed a distinct group, as previously established.200717965345
[rapid detection of three foodborne pathogenic bacteria by multiplex polymerase chain reaction-capillary electrophoresis with laser induced fluorescence detector].a method for monitoring foodborne pathogenic bacteria by multiplex polymerase chain reaction (pcr)--capillary electrophoresis (ce) with a laser induced fluorescence detector was developed. three sets of primers were designed to amplify the gene segments of uida gene in e. coli. o157:h7, inva gene in salmonella and ipah gene in shigella, individually. the multiple pcr system and the separation conditions of ce were optimized. using a capillary coated with linear polyacrylamide and sieving buffer ...200717970100
the pattern-recognition molecule nod1 is localized at the plasma membrane at sites of bacterial interaction.the pattern-recognition molecule nod1 is a critical sensor for bacterial derived diaminopimelic acid-containing peptidoglycan fragments which induces innate immune responses in epithelial cells. here we report the subcellular localization of this protein in human epithelial cells. nod1 is localized in the cytosol and at the plasma membrane in human cells. this membrane association is dependent on the integrity of the protein, on its signalling capacity and on an intact actin cytoskeleton. signal ...200817970764
the nlee/ospz family of effector proteins is required for polymorphonuclear transepithelial migration, a characteristic shared by enteropathogenic escherichia coli and shigella flexneri infections.enteropathogenic escherichia coli (epec) and shigella flexneri are human host-specific pathogens that infect intestinal epithelial cells. however, each bacterial species employs a different infection strategy within this environmental niche. epec attaches to the apical surface of small intestine enterocytes, causing microvillus effacement and rearrangement of the host cell cytoskeleton beneath adherent bacteria. in contrast, s. flexneri invades the large intestine epithelium at the basolateral m ...200817984206
epidemiology and clinical presentation of shigellosis in children less than five years of age in rural mozambique.rectal swabs were collected from 1354 children <5 years of age with diarrhea attending manhiça district hospital and from 227 healthy community controls. shigellosis incidence was high among children aged 12-47 months (488.4/10(5) child-years at risk). fever and dysentery were prominent clinical findings. shigella was more frequently isolated from cases than controls (6.7% versus 0.4%, p = 0.004), and from dysentery than nondysenteric diarrhea (24.1% versus 3.5%, p < 0.001). shigella flexneri 2a ...200717984817
type iii secretion effectors of the ipah family are e3 ubiquitin ligases.many bacteria pathogenic for plants or animals, including shigella spp., which is responsible for shigellosis in humans, use a type iii secretion apparatus to inject effector proteins into host cells. effectors alter cell signaling and host responses induced upon infection; however, their precise biochemical activities have been elucidated in very few cases. utilizing saccharomyces cerevisiae as a surrogate host, we show that the shigella effector ipah9.8 interrupts pheromone response signaling ...200718005683
microbial pathogen-induced necrotic cell death mediated by the inflammasome components cias1/cryopyrin/nlrp3 and asc.cryopyrin (cias1, nlrp3) and asc are components of the inflammasome, a multiprotein complex required for caspase-1 activation and cytokine il-1beta production. cias1 mutations underlie autoinflammation characterized by excessive il-1beta secretion. disease-associated cryopyrin also causes a program of necrosis-like cell death in macrophages, the mechanistic details of which are unknown. we find that patient monocytes carrying disease-associated cias1 mutations exhibit excessive necrosis-like dea ...200718005730
bacteriological and antigenic analysis of shigella paradysenteriae sonne isolated from 9 cases. 193218013462
isolation of shigella paradysenteriae type p288 of boyd from a case of acute diarrhea. 194418016092
secretory iga mediates bacterial translocation to dendritic cells in mouse peyer's patches with restriction to mucosal compartment.in addition to fulfilling its function of immune exclusion at mucosal surfaces, secretory iga (siga) ab exhibits the striking feature to adhere selectively to m cells in the mouse and human intestinal peyer's patches (pps). subsequent uptake drives the siga ab to dendritic cells (dcs), which become partially activated. using freshly isolated mouse dcs, we found that the interaction with siga was tissue and dc subtype dependent. only dcs isolated from pps and mesenteric lymph nodes interacted wit ...200718025221
the distribution of insertion sequences in the genome of shigella flexneri strain 2457t.shigella flexneri, which causes shigellosis in humans, evolved from escherichia coli. the sequencing of shigella genomes has revealed that a large number of insertion sequence (is) elements (over 200 elements) reside in the genome. although the presence of these elements has been noted previously and summarized, more detailed analyses are required to understand their evolutionary significance. here, the genome of s. flexneri strain 2457t is used to investigate the spatial distribution of is copi ...200718031340
saccharomyces boulardii interferes with shigella pathogenesis by postinvasion signaling events.saccharomyces boulardii is gaining in popularity as a treatment for a variety of diarrheal diseases as well as inflammatory bowel disease. this study was designed to examine the effect of this yeast on infection by shigella flexneri, a highly infectious and human host-adapted enteric pathogen. we investigated key interactions between the bacteria and host cells in the presence of the yeast in addition to a number of host responses including proinflammatory events and markers. although the presen ...200818032477
changing patterns of antimicrobial susceptibility of shigella serotypes isolated from children with acute diarrhea in manipal, south india, a 5 year study.this study was carried out to determine the current pattern of shigella serogroups and their antimicrobial resistance in children with acute gastroenteritis in manipal, south india. a total of 1,200 stool samples were collected from april 2001 to may 2006 in children suffering from acute gastroenteritis attending the out-patient department of pediatrics at kasturba hospital, manipal, south india. these samples were cultured for enteric pathogens. the isolates were confirmed to be shigella by bio ...200718041303
muramylpeptide shedding modulates cell sensing of shigella flexneri.bacterial infections trigger the activation of innate immunity through the interaction of pathogen-associated molecular patterns (pamps) with pattern recognition molecules (prms). the nucleotide-binding oligomerization domain (nod) proteins are intracellular prms that recognize muramylpeptides contained in peptidoglycan (pgn) of bacteria. it is still unclear how nod1 physically interacts with pgn, a structure internal to the gram-negative bacterial envelope. to contribute to the understanding of ...200818042252
cloning, expression, purification, characterization, crystallization and x-ray diffraction of bifunctional pyrimidine deaminase/reductase from shigella flexneri 2a.bifunctional pyrimidine deaminase/reductase (ribd) plays an important role during riboflavin biosynthesis in many microorganisms. the 40.4 kda ribd from shigella flexneri 2a has been cloned, expressed, purified and characterized. three crystals of ribd have been obtained by the hanging-drop technique at 291 k using peg 20k or nacl as precipitant. the ribd crystal using peg 20k as precipitant diffracted to 2.5a.200718045236
comparing invasive and non-invasive of isolated shigella flexneri by electron microscopy of cell culture, sds-page and congo red method.the aim of this study was to compare invasive and non-invasive strains of shigella flexneri isolated from tehran by a 120 kda protein band by sds-page, electron microscopy of cell culture and congo red dye methods.200718051704
structural insights into the enzymatic mechanism of the pathogenic mapk phosphothreonine lyase.the ospf family of phosphothreonine lyase, including spvc from salmonella, irreversibly inactivates the dual-phosphorylated host mapks (pt-x-py) through beta elimination. we determined crystal structures of spvc and its complex with a phosphopeptide substrate. spvc adopts a unique fold of alpha/beta type. the disordered n terminus harbors a canonical d motif for mapk substrate docking. the enzyme-substrate complex structure indicates that recognition of the phosphotyrosine followed by insertion ...200718060821
[expression profile analysis of host hela cells invasived by shigella flexneri 2a].the changes of genes expression in hela cell during the invasion with shigella species for 1h and 3h were analyzed by cdna microarrays. the data showed that the expression levels of 752 genes were altered twice or greater as compared with the control 509 of them were up-regulated, and 306 were down-regulated. it was supposed that some signal pathways in hela cell were activated, then many genes were induced, and at last comprehensive cell responses were produced, so that hela cell could prevent ...200718062254
systemic pharmacokinetics of rifaximin in volunteers with shigellosis.rifaximin is an oral antibiotic indicated for treatment of traveler's diarrhea. rifaximin pharmacokinetics were evaluated in individuals challenged with shigella flexneri. peak plasma rifaximin concentrations were low after nine consecutive doses, and no accumulation was observed. rifaximin serum levels were minimal and similar to those previously reported in studies of healthy volunteers.200818086855
antimicrobial susceptibility of shigella flexneri and s. dysenteriae isolated from stool specimens of patients with bloody diarrhoea in mwanza, tanzania.this study was conducted to determine frequency and pattern of antimicrobial susceptibility of shigella species isolated from stool specimens collected from patients presenting with bloody diarrhoea in mwanza city, tanzania. the study was carried out from october 2004 to october 2005 and involved patients attending sekou toure regional hospital and butimba health centre. bacteriological cultures were done at the national institute for medical research laboratory. a total of 489 patients (median ...200718087897
phenotypic and molecular characterization of tem-116 extended-spectrum beta-lactamase produced by a shigella flexneri clinical isolate from chickens.extended-spectrum beta-lactamases (esbls) produced by a clinical isolate of shigella flexneri from chickens were detected with confirmatory phenotypic tests of the clinical and laboratory standards institute, and minimum inhibitory concentrations of several antibacterial drugs against the isolate were determined by the twofold dilution method. the genotype and subtype of the esbl-producing s. flexneri isolate were identified by pcr amplifying of esbl genes and dna sequencing analysis. the result ...200818093137
effect of hand wash agents on controlling the transmission of pathogenic bacteria from hands to food.the goals of this study were to evaluate the effectiveness of two hand wash regimens in reducing transient bacteria on the skin following a single hand wash and the subsequent transfer of the bacteria to a ready-to-eat food item, freshly cut cantaloupe melon. the number of bacteria recovered from hands and the quantity transferred to the melon were significantly less following the use of an antibacterial soap compared with plain soap. the antimicrobial soap achieved > 3-log reductions versus esc ...200718095447
[type-determination of shigella paradysenteriae (flexner) and how to distinguish them from similar bacteria]. 194818126933
a new type of phase variation in the 103 race of shigella paradysenteriae. 194918127625
a field trial of shigella flexneri iii vaccine; serum agglutination studies. 194918137145
identification of the nadler type (r. ettinger-tulczinska, 1943) with shigella sp. q 1167 (large-sachs) and the presence of shigella paradysenteriae boyd iii & v (flexner xi & xiii) in israel. 194918145345
field trial of shigella flexneri iii vaccine; background, scope, and organization of the program. 194918146106
direct detection of shigella flexneri and salmonella typhimurium in human feces by real-time pcr.we have established a sybr green-based realtime pcr method using anydirect solution, which enhances pcr from whole blood, for direct amplification of the vira gene of shigella flexneri and the inva gene of salmonella typhimurium from human feces without prior dna purification. when we compared the efficiency of conventional or realtime pcr amplification of the vira and inva genes from the supernatant of boiled feces supplemented with s. flexneri and s. typhimurium in the presence or absence of a ...200718156776
full structural characterization of shigella flexneri m90t serotype 5 wild-type r-lps and its delta galu mutant: glycine residue location in the inner core of the lipopolysaccharide.shigella flexneri is a gram-negative bacterium responsible for serious enteric infections that occur mainly in the terminal ileum and colon. high interest in shigella, as a human pathogen, is driven by its antibiotic resistance and the necessity to develop a vaccine against its infections. vaccines of the last generation use carbohydrate moieties of the lipopolysaccharide as probable candidates. for this reason, the primary structure of the core oligosaccharide from the r-lps produced by s. flex ...200818174310
ph sensitivity of type iii secretion system tip proteins.many pathogenic gram-negative bacteria employ type iii secretion systems to transport proteins into the host cell membrane and cytoplasm to subvert normal cellular functions. the type iii secretion apparatus consists of a basal body spanning the inner and outer bacterial membranes and a needle which extends away from the bacterium. recent work has found that a special class of proteins localizes to the tip of the needle to control secretion of effector proteins. five of these tip proteins are ip ...200818175320
differential activation of human tlr4 by escherichia coli and shigella flexneri 2a lipopolysaccharide: combined effects of lipid a acylation state and tlr4 polymorphisms on signaling.the lipid a of lps activates tlr4 through an interaction with myeloid differentiation protein-2 (md-2) and the degree of lipid a acylation affects tlr4 responsiveness. two tlr4 single nucleotide polymorphisms (asp299gly and thr399ile) have been associated with lps hyporesponsiveness. we hypothesized that the combination of hypoacylation and these single nucleotide polymorphisms would exhibit a compounded effect on tlr4 signaling. hek293t transfectants expressing wild-type or polymorphic tlr4 wer ...200818178854
death from multi-resistant shigelloses: a case study from fiji.death from shigellosis is rare in developed countries, however it causes over a million deaths in developing countries worldwide annually. death from shigellosis is rare in fiji. however, the global problem of emerging multi-drug resistance raises some issues about the management of shigellosis in this country. within fiji, shigella is a notifiable disease. the fiji ministry of health recorded 68 cases of shigella in 1996, 173 cases in 1997 and 334 cases in 1998 (no data available for 1999). the ...200618181399
cytoplasmic targeting of ipac to the bacterial pole directs polar type iii secretion in shigella.type iii secretion (t3s) systems are largely used by pathogenic gram-negative bacteria to inject multiple effectors into eukaryotic cells. upon cell contact, these bacterial microinjection devices insert two t3s substrates into host cell membranes, forming a so-called 'translocon' that is required for targeting of type iii effectors in the cell cytosol. here, we show that secretion of the translocon component ipac of invasive shigella occurs at the level of one bacterial pole during cell invasio ...200818188151
bacterial actin assembly requires toca-1 to relieve n-wasp autoinhibition.actin polymerization in the mammalian cytosol can be locally activated by mechanisms that relieve the autoinhibited state of n-wasp, an initiator of actin assembly, a process that also requires the protein toca-1. several pathogenic bacteria, including shigella, exploit this host feature to infect and disseminate efficiently. the shigella outer membrane protein icsa recruits n-wasp, which upon activation at the bacterial surface mediates localized actin polymerization. the molecular role of toca ...200818191793
the chaperone ipgc copurifies with the virulence regulator mxie.the expression of a subset of shigella flexneri virulence genes is dependent upon a cytoplasmic chaperone, ipgc, and an activator from the arac/xyls family, mxie. in this paper, we report that the chaperone forms a specific and stable heteromer with mxie.200818192384
role and regulation of iron-sulfur cluster biosynthesis genes in shigella flexneri virulence.shigella flexneri, a causative agent of bacterial dysentery, possesses two predicted iron-sulfur cluster biosynthesis systems called suf and isc. s. flexneri strains containing deletion mutations in the entire suf operon (ur011) or the iscsua genes (ur022) were constructed. both mutants were defective in surviving exposure to oxidative stress. the suf mutant showed growth that was comparable to that of the parental strain in both iron-replete and iron-limiting media; however, the isc mutant show ...200818195027
molecular pathogenesis of shigella spp.: controlling host cell signaling, invasion, and death by type iii secretion.shigella spp. are gram-negative pathogenic bacteria that evolved from harmless enterobacterial relatives and may cause devastating diarrhea upon ingestion. research performed over the last 25 years revealed that a type iii secretion system (t3ss) encoded on a large plasmid is a key virulence factor of shigella flexneri. the t3ss determines the interactions of s. flexneri with intestinal cells by consecutively translocating two sets of effector proteins into the target cells. thus, s. flexneri co ...200818202440
phase 1 clinical trial of live attenuated shigella dysenteriae type-1 deltaicsa deltaent deltafep deltastxa:hgr oral vaccine sc599 in healthy human adult volunteers.twenty-eight adults received between 10(2) and 10(8)colony forming units of live shigella dysenteriae type-1 vaccine sc599, attenuated by deletion of invasion (icsa), iron chelation (ent, fep) and shiga toxin a-subunit (stxa) genes, followed by ciprofloxacin on day 4. dose-independent diarrhea or change in bowel habit was seen in 3 subjects, without dysentery, vaccinaemia or serious adverse events. hematology and biochemical parameters were unchanged. doses of 10(5) or greater induced dose-indep ...200818207287
[antimicrobial effect of 4-(adamantyl-1)-1-(1-aminobutyl)benzol].antimicrobial activity in vitro of adamantine derivative in respect of aerobic and anaerobic microorganisms has been studied. in these conditions gram-positive bacteria and some representatives of gram-negative microorganisms (shigella flexneri, s. newvcastle, enterobacter aerogenes etc.) had maximal sensitivity (mic 0.6-5.0 and 0.1-5.0 mg/ml, respectively). pseudomonas aeruginosa were resistant to this substance (mic >1 mg/ml).200718217353
regulation of expression and secretion of nleh, a new non-locus of enterocyte effacement-encoded effector in citrobacter rodentium.together with enterohemorrhagic escherichia coli and enteropathogenic escherichia coli, citrobacter rodentium is a member of the attaching-and-effacing (a/e) family of bacterial pathogens. a/e pathogens use a type iii secretion system (t3ss) to translocate an assortment of effector proteins, encoded both within and outside the locus of enterocyte effacement (lee), into the colonized host cell, leading to the formation of a/e lesions and disease. here we report the identification and characteriza ...200818223087
cmy-2-type plasmid-mediated ampc beta-lactamase finally emerging in argentina. 200818242960
on-line monitoring of microbial volatile metabolites by proton transfer reaction-mass spectrometry.a method for analysis of volatile organic compounds (vocs) from microbial cultures was established using proton transfer reaction-mass spectrometry (ptr-ms). a newly developed sampling system was coupled to a ptr-ms instrument to allow on-line monitoring of vocs in the dynamic headspaces of microbial cultures. the novel ptr-ms method was evaluated for four reference organisms: escherichia coli, shigella flexneri, salmonella enterica, and candida tropicalis. headspace vocs in sampling bottles con ...200818245241
extracellular-loop peptide antibodies reveal a predominant hemichannel organization of connexins in polarized intestinal cells.shigella, the causative agent of bacillary dysentery, invades colonic epithelial cells to elicit an intense inflammatory reaction leading to destruction of the mucosa. atp-dependent paracrine signalling induced by connexin (cx) hemichannel opening was previously shown to favor shigella flexneri invasion and dissemination in transfectants of hela cells [g. tran van nhieu, c. clair, r. bruzzone, m. mesnil, p. sansonetti and l. combettes. (2003). connexin-dependent intercellular communication incre ...200818267319
immunogenicity and efficacy of highly purified invasin complex vaccine from shigella flexneri 2a.development of a subunit vaccine for shigellosis requires identification of protective antigens and delivering these antigens in a manner that stimulates immunity comparable to that induced by natural infection. the shigella invasin complex (invaplex) vaccine is an ion-exchange-purified extract from virulent shigella that consists of lps and several other proteins, including the invasins ipab and ipac. intranasal delivery of invaplex stimulates protective immunity in small animal models for shig ...200818276045
distribution and antibiotic susceptibility of shigella isolates in bangui, central african republic.we conducted a prospective study in four urban health care centres between january 2004 and november 2005 to determine the distribution and susceptibility patterns of shigella strains causing invasive diarrhoea in bangui, central african republic. of the 155 shigella isolated, shigella flexneri (51%) and shigella dysenteriae (30%) were the most common and the most resistant to usual antibiotics, including amoxicillin, sulphamethoxazole-trimethoprim and chloramphenicol. though multi-drug resistan ...200818282240
the shf gene of a shigella flexneri homologue on the virulent plasmid paa2 of enteroaggregative escherichia coli 042 is required for firm biofilm formation.enteroaggregative escherichia coli (eaec) is an increasingly important cause of diarrhea in both developing and industrialized countries, and is characterized by strong biofilm formation on the intestinal mucosa. sequencing of the virulent plasmid paa2 of the prototype eaec 042 revealed a cluster of three open reading frames (orfs; shf, capu, and virk) ca. 93% identical to a similar cluster located in shigella flexneri. the function of the first orf shf protein is not known, but the closest well ...200818293034
terpenoid compositions, and antioxidant and antimicrobial properties of the rhizome essential oils of different hedychium species.a phytochemical study of the rhizome essential oils of four different hedychium species was performed by means of gc and gc/ms analyses. h. ellipticum mainly contained 1,8-cineole, sabinene, and terpin-4-ol, while h. aurantiacum possessed terpin-4-ol, para-cymene, and bornyl acetate as the major entities. similarly, trans-meta-mentha-2,8-diene and linalool were noticed in h. coronarium. three different collections (i-iii) of h. spicatum showed amazing differences in the relative contents of thei ...200818293443
single residue determines the specificity of neutrophil elastase for shigella virulence factors.human neutrophil elastase (ne) is a key host defense protease that cleaves virulence factors of gram-negative bacteria. ne and cathepsin g (cg) are chymotrypsin-like serine proteases with sequence and structural similarities, and both are abundant in neutrophil granules. unlike ne, cg does not cleave virulence factors of enteric bacteria. through structure-function analysis, we identified regions in ne that are essential for cleaving shigella virulence proteins. ne residues at eight different po ...200818295791
geographic analysis of shigellosis in vietnam.geographic and ecological analysis may provide investigators useful ecological information for the control of shigellosis. this paper provides distribution of individual shigella species in space, and ecological covariates for shigellosis in nha trang, vietnam. data on shigellosis in neighborhoods were used to identify ecological covariates. a bayesian hierarchical model was used to obtain joint posterior distribution of model parameters and to construct smoothed risk maps for shigellosis. neigh ...200818296100
structures of the shigella flexneri type 3 secretion system protein mxic reveal conformational variability amongst homologues.many gram-negative pathogenic bacteria use a complex macromolecular machine, known as the type 3 secretion system (t3ss), to transfer virulence proteins into host cells. the t3ss is composed of a cytoplasmic bulb, a basal body spanning the inner and outer bacterial membranes, and an extracellular needle. secretion is regulated by both cytoplasmic and inner membrane proteins that must respond to specific signals in order to ensure that virulence proteins are not secreted before contact with a euk ...200818304577
ipgb1 and ipgb2, two homologous effectors secreted via the mxi-spa type iii secretion apparatus, cooperate to mediate polarized cell invasion and inflammatory potential of shigella flexenri.type iii secretion systems (t3ss) are present in many pathogenic gram-negative bacteria and mediate the translocation of bacterial effector proteins into host cells. here, we report the phenotypic characterization of s. flexneri ipgb1 and ipgb2 mutants, in which the genes encoding the ipgb1 and ipgb2 effectors have been inactivated, either independently or simultaneously. like ipgb1, we found that ipgb2 is secreted by the t3ss and its secretion requires the spa15 chaperone. upon infection of sem ...200818316224
delivery of biologically active anti-inflammatory cytokines il-10 and il-1ra in vivo by the shigella type iii secretion apparatus.pathogenicity of many gram-negative bacteria relies on a type iii secretion (t3s) apparatus, which is used for delivery of bacterial effectors into the host cell cytoplasm allowing the bacteria to manipulate host cell cytoskeleton network as well as to interfere with intracellular signaling pathways. in this study, we investigated the potential of the shigella flexneri t3sa as an in vivo delivery system for biologically active molecules such as cytokines. the anti-inflammatory cytokines il-10 an ...200818322242
impact of infections and normal flora in nonhuman primates on drug development.preclinical safety studies that are required for the marketing approval of a pharmaceutical include single and repeat dose studies in rodent and nonrodent species. the use of nonhuman primates (nhps), primarily macaques, as the nonrodent species has increased in recent years, in part due to the increase in development of biopharmaceuticals and immunomodulatory agents. depending on the source of the macaques, they may vary in genetic background, normal flora, and/or the incidence of preexisting p ...200818323580
cold shock exoribonuclease r (vacb) is involved in aeromonas hydrophila pathogenesis.in this study, we cloned and sequenced a virulence-associated gene (vacb) from a clinical isolate ssu of aeromonas hydrophila. we identified this gene based on our recently annotated genome sequence of the environmental isolate atcc 7966(t) of a. hydrophila and the vacb gene of shigella flexneri. the a. hydrophila vacb protein contained 798 amino acid residues, had a molecular mass of 90.5 kda, and exhibited an exoribonuclease (rnase r) activity. the rnase r of a. hydrophila was a cold-shock pro ...200818344363
maturation of paneth cells induces the refractory state of newborn mice to shigella infection.the intestinal tract of adult mice is naturally resistant to infection by shigella, the causative agent of bacillary dysentery in humans. conversely, newborn mice are highly susceptible to intragastric shigella infection and develop inflammatory lesions of the jejunal mucosa, very similar to those observed in the colon of dysenteric patients. however, the susceptibility period is short and one week after birth, animals have acquired a status of resistance characteristic of adult animals. to iden ...200818354217
differential expression of ompc and ompf in multidrug-resistant shigella dysenteriae and shigella flexneri by aqueous extract of aegle marmelos, altering its susceptibility toward beta-lactam antibiotics.steadily increasing resistance among shigella to beta-lactams, aminoglycosides, and tetracycline has compromised the utility of these commonly used antimicrobial agents. also, undesirable side effects of certain antibiotics have triggered immense interest in search of alternative therapies using medicinal plants. one such medicinal plant used since ancient times to cure diarrhea is aegle marmelos. the present study exemplifies the susceptibility of beta-lactam-resistant shigella dysenteriae and ...200818358664
differential regulation by magnesium of the two msbb paralogs of shigella flexneri.shigella flexneri, a gram-negative enteric pathogen, is unusual in that it contains two nonredundant paralogous genes that encode the myristoyl transferase msbb (lpxm) that catalyzes the final step in the synthesis of the lipid a moiety of lipopolysaccharide. msbb1 is encoded on the chromosome, and msbb2 is encoded on the large virulence plasmid present in all pathogenic shigellae. we demonstrate that myristoyl transferase activity due to msbb2 is detected in limited magnesium medium, but not in ...200818359815
analysis of rho-gtpase mimicry by a family of bacterial type iii effector proteins.microbial pathogens may hijack the actin cytoskeleton machinery to facilitate actin-based motility, cellular invasion, and intracellular trafficking through the endocytic pathway. of particular interest has been a large class of virulence factors collectively termed the type iii "effector" proteins. following contact with a eukaryotic cell, gram-negative bacterial pathogens employ a dedicated protein secretion apparatus termed type iii to translocate effector proteins into the cellular cytoplasm ...200818374161
coiled-coil regions play a role in the function of the shigella flexneri o-antigen chain length regulator wzzphs2.regulation of the length of the o-antigen (oag) chain attached to lps in shigella flexneri is important for virulence and is dependent on the inner-membrane protein wzz. a lack of high-resolution structural data for wzz has hampered efforts so far to correlate mutations affecting function of wzz with structure and describe a mechanism for chain length regulation. here we have used secondary structure prediction to show that the periplasmic domain of the wzz(phs2) protein has three regions of sig ...200818375803
ospf directly attenuates the activity of extracellular signal-regulated kinase during invasion by shigella flexneri in human dendritic cells.shigella spp., gram-negative pathogenic bacteria, deliver various effector molecules into the host cell cytoplasm through their type iii secretion system to facilitate their invasive process and control the host innate immune responses. although the function of these effectors is well characterized in epithelial cells during shigella infection, it has not been elucidated in the dendritic cell (dc), a major antigen presenting cell playing an important role in the initiation of immune responses. i ...200818378312
a pharmacokinetic study of enrofloxacin and its active metabolite ciprofloxacin after oral and intramuscular dosing of enrofloxacin in rhesus monkeys (macaca mulatta).enrofloxacin is used for treating shigellosis in non-human primates; however, there are no reports describing its pharmacokinetics in rhesus monkeys. pharmacokinetic data in intended target species (rhesus) help to determine the proper dose regimen. blood levels of enrofloxacin and ciprofloxacin (enrofloxacin's active metabolite), were determined after either intramuscular or oral dosing of enrofloxacin for 7 days in a cross-over study. levels of both antibiotics were determined by solid phase e ...200818384536
analysis of bacterial dna in synovial tissue of tunisian patients with reactive and undifferentiated arthritis by broad-range pcr, cloning and sequencing.bacteria and/or their antigens have been implicated in the pathogenesis of reactive arthritis (rea). several studies have reported the presence of bacterial antigens and nucleic acids of bacteria other than those specified by diagnostic criteria for rea in joint specimens from patients with rea and various arthritides. the present study was conducted to detect any bacterial dna and identify bacterial species that are present in the synovial tissue of tunisian patients with reactive arthritis and ...200818412942
containment of tumor-colonizing bacteria by host neutrophils.administration of facultative anaerobic bacteria like salmonella typhimurium, shigella flexneri, and escherichia coli to tumor-bearing mice leads to a preferential accumulation and proliferation of the microorganisms within the solid tumor. until now, all known tumor-targeting bacteria have shown poor dissemination inside the tumors. they accumulate almost exclusively in large necrotic areas and spare a rim of viable tumor cells. interestingly, the bacteria-containing necrotic region is separate ...200818413765
structure and genetics of shigella o antigens.this review covers the o antigens of the 46 serotypes of shigella, but those of most shigella flexneri are variants of one basic structure, leaving 34 shigella distinct o antigens to review, together with their gene clusters. several of the structures and gene clusters are reported for the first time and this is the first such group for which structures and dna sequences have been determined for all o antigens. shigella strains are in effect escherichia coli with a specific mode of pathogenicity ...200818422615
role of rna polymerase sigma-factor (rpos) in induction of glutamate-dependent acid-resistance of escherichia albertii under anaerobic conditions.escherichia albertii is a potential enteric food-borne pathogen with poorly defined genetic and biochemical properties. acid resistance is perceived to be an important property of enteric pathogens, enabling them to survive passage through stomach acidity so that they may colonize the mammalian gastrointestinal tract. we analyzed glutamate-dependent acid-resistance pathway (gdar) in five e. albertii strains that have been identified so far. we observed that the strains were unable to induce gdar ...200818422618
comparing the antimicrobial effectiveness of nacl and kcl with a view to salt/sodium replacement.a study using a small range of pathogenic bacterial species (aeromonas hydrophila, enterobacter sakazakii, shigella flexneri, yersinia enterocolitica and 3 strains of staphylococcus aureus) has shown that potassium chloride has an equivalent antimicrobial effect on these organisms when calculated on a molar basis. combined nacl and kcl experiments were carried out and data was analysed using a modification to the lambert and lambert [lambert, r.j.w., and lambert, r., 2003. a model for the effica ...200818423764
virulent shigella flexneri subverts the host innate immune response through manipulation of antimicrobial peptide gene expression.antimicrobial factors are efficient defense components of the innate immunity, playing a crucial role in the intestinal homeostasis and protection against pathogens. in this study, we report that upon infection of polarized human intestinal cells in vitro, virulent shigella flexneri suppress transcription of several genes encoding antimicrobial cationic peptides, particularly the human beta-defensin hbd-3, which we show to be especially active against s. flexneri. this is an example of targeted ...200818426984
alternative hand contamination technique to compare the activities of antimicrobial and nonantimicrobial soaps under different test conditions.antimicrobial hand soaps provide a greater bacterial reduction than nonantimicrobial soaps. however, the link between greater bacterial reduction and a reduction of disease has not been definitively demonstrated. confounding factors, such as compliance, soap volume, and wash time, may all influence the outcomes of studies. the aim of this work was to examine the effects of wash time and soap volume on the relative activities and the subsequent transfer of bacteria to inanimate objects for antimi ...200818441107
shigellosis: the current status of vaccine development.shigellosis, a major form of bacillary dysentery, is caused by infection with shigella organisms. in poor countries, shigella-caused dysentery is endemic and causes an estimated 163 million illness episodes annually and more than one million deaths. although several strategies have been used to develop vaccines targeting shigellosis, none has been licensed for use outside china. owing to the wide range of shigella serotypes and subtypes, there is a need for a multivalent vaccine representing pre ...200818448978
deoxycholate interacts with ipad of shigella flexneri in inducing the recruitment of ipab to the type iii secretion apparatus needle tip.type iii secretion (tts) is an essential virulence function for shigella flexneri that delivers effector proteins that are responsible for bacterial invasion of intestinal epithelial cells. the shigella tts apparatus (ttsa) consists of a basal body that spans the bacterial inner and outer membranes and a needle exposed at the pathogen surface. at the distal end of the needle is a "tip complex" composed of invasion plasmid antigen d (ipad). ipad not only regulates tts, but is required for the rec ...200818450744
mutagenesis of the shigella flexneri autotransporter icsa reveals novel functional regions involved in icsa biogenesis and recruitment of host neural wiscott-aldrich syndrome protein.the icsa (virg) protein of shigella flexneri is a polarly localized, outer membrane protein that is essential for virulence. within host cells, icsa activates the host actin regulatory protein, neural wiskott-aldrich syndrome protein (n-wasp), which in turn recruits the arp2/3 complex, which nucleates host actin to form f-actin comet tails and initiate bacterial motility. linker insertion mutagenesis was undertaken to randomly introduce 5-amino-acid in-frame insertions within icsa. forty-seven l ...200818456802
an intersubunit active site between supercoiled parallel beta helices in the trimeric tailspike endorhamnosidase of shigella flexneri phage sf6.sf6 belongs to the podoviridae family of temperate bacteriophages that infect gram-negative bacteria by insertion of their double-stranded dna. they attach to their hosts specifically via their tailspike proteins. the 1.25 a crystal structure of shigella phage sf6 tailspike protein (sf6 tsp) reveals a conserved architecture with a central, right-handed beta helix. in the trimer of sf6 tsp, the parallel beta helices form a left-handed, coiled-beta coil with a pitch of 340 a. the c-terminal domain ...200818462681
immunological evidence for functional rather than structural mimicry by a shigella flexneri y polysaccharide-mimetic peptide.an approach to vaccine design is the use of molecules that mimic the immunogenic element of interest. in this context, the interaction of mdwnmhaa, a peptide mimic of the shigella flexneri y o polysaccharide (ps), with an anti-carbohydrate monoclonal antibody, as studied previously by x-ray crystallography, suggested the presence of functional rather than structural mimicry and a bound peptide conformation that was not represented significantly in the free-ligand ensemble. the antibody response ...200818463226
simple sequence repeats in different genome sequences of shigella and comparison with high gc and at-rich genomes.simple sequence repeats (ssrs) are omnipresent in prokaryotes and eukaryotes, and are found anywhere in the genome in both protein encoding and noncoding regions. in present study the whole genome sequences of seven chromosomes (shigella flexneri 2a str301 and 2457t, shigella sonnei, escherichia coli k12, mycobacterium tuberculosis, mycobacterium leprae and staphylococcus saprophyticus) have downloaded from the genbank database for identifying abundance, distribution and composition of ssrs and ...200818464038
identification of novel genomic islands associated with small rnas.genome evolution in prokaryotes is assisted by integration of gene pools from phages and plasmids. regions downstream of trnas and tmrnas are considered as hot spots for the integration of these gene pools or genomic islands. till date, genomic islands have been identified only at trna/tmrna genes in the enterobacterial genomes. present work reports 10 distinct small rnas as potent integration sites for genomic islands. a known tool trnacc 1.0 has been used to identify genomic islands associated ...200718467773
safety and immunogenicity of wrsd1, a live attenuated shigella dysenteriae type 1 vaccine candidate.among shigella serotypes shigella dysenteriae type 1 produces the most severe disease, including cases of hemolytic-uremic syndrome and pandemic outbreaks. wrsd1 is a live s. dysenteriae 1 strain attenuated by deletion of the virg(icsa) gene, which encodes a protein that mediates intercellular spread, and stxa and stxb, which encode the shiga toxin. in this phase i trial five groups of eight subjects ingested escalating doses of wrsd1 ranging from 10(3) to 10(7)cfu. no subject experienced fever ...200818468742
synthesis, characterization and antimicrobial activity of d metal complexes of some 2-substituted-1h-benzimidazoles.the metal complexes of nine 2-substituted-1h-benzimidazoles (i-ix) with ni(ii), pd(ii), cu(ii), ag(i), zn(ii) salts were synthesized. the compounds were characterized by melting point, analytical data, ir spectroscopy and magnetic susceptibility. the antimicrobial activity of the compounds was determined by the disk diffusion method in mueller-hinton agar on staphylococcus aureusatcc 6538, staphylococcus epidermidis atcc 12228, escherichia coli atcc 8739, klebsiella pneumoniae atcc 4352, pseudom ...199918472907
antimicrobial susceptibility of shigella isolates in eight asian countries, 2001-2004.shigellosis is a major health problem in developing countries, causing 91 million episodes and 414,000 deaths in asia annually. because of increasing trends towards drug resistance, this study was undertaken to monitor local resistance patterns of shigella isolates from 8 asian countries.200818473096
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