Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| structure-function analysis of the shigella virulence factor ipab. | infection by the gram-negative bacterium shigella flexneri results in dysentery, an acute inflammatory disease of the colon. essential events in the pathogenesis of shigella infections include bacterial invasion of epithelial cells, escape from the phagosome, and induction of apoptosis in macrophages. the shigella virulence factor invasion plasmid antigen b (ipab) is required for all of these processes. induction of apoptosis is dependent on ipab binding to the cysteine protease caspase-1 (casp- ... | 2001 | 11157939 |
| production and characterization of a new monoclonal antibody against neisseria meningitidis: study of the cross-reactivity with different bacterial genera. | we have generated a hybridoma cell line which produces an 8c7br1 clone of the igm antibody isotype. it recognizes the 50-, 65-, and 60-kda antigens and is reactive with strains of n. meningitidis in the 98% of local neisseria genera by dot-elisa assays. two percent of the strains of n. meningitidis b do not present reactivity with the 8c7br1 monoclonal antibody (mab). the antibody reacted against n. meningitidis of serogroups a, b, c, x, y, z, and different serotypes and subtypes of n. meningiti ... | 2000 | 11152396 |
| conserved regulatory elements of the promoter sequence of the gene rpoh of enteric bacteria. | the rpoh regulatory region of different members of the enteric bacteria family was sequenced or downloaded from genbank and compared. in addition, the transcriptional start sites of rpoh of yersinia frederiksenii and proteus mirabilis, two distant members of this family, were determined. sequences similar to the sigma(70) promoters p1, p4 and p5, to the sigma(e) promoter p3 and to boxes dnaa1, dnaa2, camp receptor protein (crp) boxes crp1, crp2 and box cytr present in escherichia coli k12, were ... | 2001 | 11139607 |
| inactivation of gram-negative bacteria by lysozyme, denatured lysozyme, and lysozyme-derived peptides under high hydrostatic pressure. | we have studied the inactivation of six gram-negative bacteria (escherichia coli, pseudomonas fluorescens, salmonella enterica serovar typhimurium, salmonella enteritidis, shigella sonnei, and shigella flexneri) by high hydrostatic pressure treatment in the presence of hen egg-white lysozyme, partially or completely denatured lysozyme, or a synthetic cationic peptide derived from either hen egg white or coliphage t4 lysozyme. none of these compounds had a bactericidal or bacteriostatic effect on ... | 2001 | 11133464 |
| identification of functional regions within invasion plasmid antigen c (ipac) of shigella flexneri. | shigella flexneri causes bacillary dysentery with symptoms resulting from the inflammation that accompanies bacterial entry into the cells of the colonic epithelium. the effectors of s. flexneri invasion are the ipa proteins, particularly ipab and ipac, which are secreted at the host-pathogen interface following bacterial contact with a host cell. of the purified ipa proteins, only ipac has been shown to possess quantifiable in vitro activities that are related to cellular invasion. in this stud ... | 2001 | 11123692 |
| shigella flexneri luxs quorum-sensing system modulates virb expression but is not essential for virulence. | quorum-sensing systems regulate the expression of virulence factors in a wide variety of plant and animal pathogens, including members of the enterobacteriaceae. studies of shigella virulence gene expression have demonstrated that maximal expression of genes encoding the type iii secretion system and its substrates and maximal activity of this virulence organelle occur at high cell density. in these studies, we demonstrate that the expression of ipa, mxi, and spa invasion operons is maximal in s ... | 2001 | 11119484 |
| further studies on the gs element. a novel mycobacterial insertion sequence (is1612), inserted into an acetylase gene (mpa) in mycobacterium avium subsp. silvaticum but not in mycobacterium avium subsp. paratuberculosis. | we have recently described the gs element, found in mycobacterium avium subsp. paratuberculosis (map), mycobacterium avium subsp. silvaticum (mas) and some isolates of mycobacterium avium subsp. avium serotype 2 (maas2), which contains a set of genes of low gc% content, putatively associated with the biosynthesis, modification and transference of fucose to cell wall glycopeptidolipids. here we describe a further gene of low gc% content (mpa), within the gs element in map. mpa is a putative acety ... | 2000 | 11118730 |
| the virulence plasmid pwr100 and the repertoire of proteins secreted by the type iii secretion apparatus of shigella flexneri. | bacteria of shigella spp. are the causative agents of shigellosis. the virulence traits of these pathogens include their ability to enter into epithelial cells and induce apoptosis in macrophages. expression of these functions requires the mxi-spa type iii secretion apparatus and the secreted ipaa-d proteins, all of which are encoded by a virulence plasmid. in wild-type strains, the activity of the secretion apparatus is tightly regulated and induced upon contact of bacteria with epithelial cell ... | 2000 | 11115111 |
| studies of the small bowel surface by scanning electron microscopy in infants with persistent diarrhea. | we describe the ultrastructural abnormalities of the small bowel surface in 16 infants with persistent diarrhea. the age range of the patients was 2 to 10 months, mean 4.8 months. all patients had diarrhea lasting 14 or more days. bacterial overgrowth of the colonic microflora in the jejunal secretion, at concentrations above 10(4) colonies/ml, was present in 11 (68.7%) patients. the stool culture was positive for an enteropathogenic agent in 8 (50.0%) patients: for epec o111 in 2, epec o119 in ... | 2000 | 11105095 |
| isolation and characterization of a shigella flexneri invasin complex subunit vaccine. | the invasiveness and virulence of shigella spp. are largely due to the expression of plasmid-encoded virulence factors, among which are the invasion plasmid antigens (ipa proteins). after infection, the host immune response is directed primarily against lipopolysaccharide (lps) and the virulence proteins (ipab, ipac, and ipad). recent observations have indicated that the ipa proteins (ipab, ipac, and possibly ipad) form a multiprotein complex capable of inducing the phagocytic event which intern ... | 2000 | 11083774 |
| uptake pathways of clinical and healthy animal isolates of campylobacter jejuni into int-407 cells. | campylobacter jejuni isolates obtained from human and animal sources showed different invasion levels into human embryonic intestinal (int-407) cells. there was no significant relation between the degree of invasion and cytotoxins production. the depolymerization of both microfilaments by cytochalasin-d and microtubules by colchicine, demecolcine and nocodazole or stabilization of microtubules by paclitaxel reduced the invasiveness of c. jejuni, although microfilament depolymerization showed gre ... | 2000 | 11064267 |
| shigella flexneri bacteremia in a middle-aged immunocompetent woman. | 2000 | 11055675 | |
| the ternary transformation system: constitutive virg on a compatible plasmid dramatically increases agrobacterium-mediated plant transformation. | this paper describes a so-called ternary transformation system for plant cells. we demonstrate that agrobacterium tumefaciens strain lba4404 supplemented with a constitutive virg mutant gene (virgn54d) on a compatible plasmid is capable of very efficient t-dna transfer to a diverse range of plant species. for the plant species catharanthus roseus it is shown that increased t-dna transfer results in increased stable transformation frequencies. analysis of stably transformed c. roseus cell lines s ... | 2000 | 11052201 |
| zentralblatt für bakteriologie--100 years ago: the isolation of shigella flexneri. | 2000 | 11043976 | |
| key role for dsba in cell-to-cell spread of shigella flexneri, permitting secretion of ipa proteins into interepithelial protrusions. | dsba, a disulfide bond catalyst, is necessary for realization of the pathogenic potential of shigella flexneri. sh42, a mutant strain differing from wild-type m90ts solely because it expresses nonfunctional dsba33g (substitution for 33c at the active site), secreted less ipab and ipac than m90ts in response to various stimuli in vitro. a kinetic study demonstrated that sh42 responded more slowly to congo red than m90ts. by modulating relative concentrations of functional and nonfunctional dsba w ... | 2000 | 11035758 |
| bifidobacterium strains from resident infant human gastrointestinal microflora exert antimicrobial activity. | the gastrointestinal microflora exerts a barrier effect against enteropathogens. the aim of this study was to examine if bifidobacteria, a major species of the human colonic microflora, participates in the barrier effect by developing antimicrobial activity against enterovirulent bacteria. | 2000 | 11034580 |
| ipgd, a protein secreted by the type iii secretion machinery of shigella flexneri, is chaperoned by ipge and implicated in entry focus formation. | invasion of epithelial cells by shigella flexneri involves entry and intercellular dissemination. entry of bacteria into non-phagocytic cells requires the ipaa-d proteins that are secreted by the mxi-spa type iii secretion machinery. type iii secretion systems are found in several gram-negative pathogens and serve to inject bacterial effector proteins directly into the cytoplasm of host cells. in this study, we have analysed the ipgd protein of s. flexneri, the gene of which is located on the vi ... | 2000 | 11029686 |
| vibrio fischeri lipopolysaccharide induces developmental apoptosis, but not complete morphogenesis, of the euprymna scolopes symbiotic light organ. | during initiation of the association between the squid host euprymna scolopes and its bacterial partner vibrio fischeri, the bacteria induce dramatic morphogenesis of the host symbiotic organ, a portion of which involves the signaling of widespread apoptosis of the cells in a superficial ciliated epithelium on the colonized organ. in this study, we investigated the role in this process of lipopolysaccharide (lps), a bacterial cell-surface molecule implicated in the induction of animal cell apopt ... | 2000 | 11023684 |
| isolation and antibiotic susceptibility of salmonella, shigella, and campylobacter from acute enteric infections in egypt. | while campylobacter, salmonella, and shigella remain major contributors to acute enteric infections, few studies on these pathogens have been conducted in egypt. from january 1986 to december 1993, 869 salmonella, shigella and campylobacter strains were isolated from stool specimens from 6,278 patients, presenting to the abbassia fever hospital, cairo, egypt, with acute enteric infections. salmonella predominated, totalling 465 isolates, followed by shigella with 258 isolates, and campylobacter ... | 2000 | 11014768 |
| improved template preparation for pcr-based assays for detection of food-borne bacterial pathogens. | shigella flexneri, salmonella enterica serotype typhimurium, and listeria monocytogenes were applied to fta filters, and the filters were used directly as templates to demonstrate their sensitivity and applicability in pcr-based detection assays. with pure cultures, the sensitivities of detection by fta filter-based pcr were 30 to 50 and 200 cfu for the gram-negative enterics and listeria, respectively. different numbers of s. flexneri cells were used in controlled contamination experiments with ... | 2000 | 11010913 |
| genetic analysis of escherichia coli k1 gastrointestinal colonization. | strains of escherichia coli expressing the k1 polysaccharide capsule colonize the large intestine of newborn infants, and are the leading cause of gram-negative septicaemia and meningitis in the neonatal period. we used signature-tagged mutagenesis (stm) to identify genes that e. coli k1 requires to colonize the gastrointestinal (gi) tract. a total of 2140 mtn5 mutants was screened for their capacity to colonize the gi tract of infant rats, and 16 colonization defective mutants were identified. ... | 2000 | 10998163 |
| triphenyltin salicylate-antimicrobial effect and resistance--the pyrophosphatase connection. | the effect of triphenyltin salicylate (tps) was tested against six bacteria, escherichia coli, staphylococcus aureus, shigella flexneri, pseudomonas aeruginosa, klebsiella pneumoniae and salmonella typhi and five fungi, aspergillus flavus, aspergillus fumigatus, aspergillus niger, rhodotorula spp. and saccharomyces spp. sensitivity tests were determined with 5-500 microg/ml of tps. all organisms were sensitive to the compound except klebsiella pneumoniae, pseudomonas aeruginosa, rhodotorula spp. ... | 2000 | 10995071 |
| tripeptidyl peptidase ii promotes maturation of caspase-1 in shigella flexneri-induced macrophage apoptosis. | the invasive enteropathogenic bacterium shigella flexneri activates apoptosis in macrophages. shigella-induced apoptosis requires caspase-1. we demonstrate here that tripeptidyl peptidase ii (tppii), a cytoplasmic, high-molecular-weight protease, participates in the apoptotic pathway triggered by shigella. the tppii inhibitor ala-ala-phe-chloromethylketone (aaf-cmk) and clasto-lactacystin beta-lactone (lactacystin), an inhibitor of both tppii and the proteasome, protected macrophages from shigel ... | 2000 | 10992446 |
| myosin light chain kinase plays an essential role in s. flexneri dissemination. | shigella flexneri, the causitive agent of bacillary dysentery, has been shown to disseminate in colonic epithelial cells via protrusions that extend from infected cells and are endocytosed by adjacent cells. this phenomenon occurs in the region of the eukaryotic cell's adherens junctions and is inhibited by pharmacological reagents or host cell mutations that completely disrupt the junctional complex. in this study, inhibitors of the myosin light chain kinase (mlck) were shown to dramatically de ... | 2000 | 10984429 |
| treatment of bacillary dysentery in vietnamese children: two doses of ofloxacin versus 5-days nalidixic acid. | nalidixic acid (na: 55 mg/kg daily for 5 days) is the recommended treatment for uncomplicated bacillary dysentery in areas where multidrug-resistant shigella are prevalent. an open randomized comparison of this na regimen with 2 doses of ofloxacin (total 15 mg/kg) was conducted in 1995/96 in 135 vietnamese children with fever and bloody diarrhoea. sixty-six children with a bacterial pathogen isolated were eligible for analysis. of the 63 shigella isolates, 39 (62%) were resistant to multiple ant ... | 2000 | 10975012 |
| galanin-1 receptor up-regulation mediates the excess colonic fluid production caused by infection with enteric pathogens. | galanin is widely distributed in enteric nerve terminals lining the gastrointestinal tract. we previously showed that pathogenic escherichia coli, but not normal commensal organisms, increase galanin-1 receptor expression by epithelial cells lining the colon (i.e., colonocytes). when present, galanin-1 receptor activation by ligand causes colonocyte cl- secretion. we herein demonstrate that disparate pathogens including salmonella typhimurium and shigella flexerii also increase colonocyte galani ... | 2000 | 10973327 |
| characterization of the interaction of ipab and ipad, proteins required for entry of shigella flexneri into epithelial cells, with a lipid membrane. | entry of shigella flexneri into epithelial cells and lysis of the phagosome involve the ipab, ipac, and ipad proteins, which are secreted by type iii secretion machinery. we report here the purification of ipab and ipad and the characterization of their lipid-binding properties as a function of ph. the interaction of ipab with the membrane was quite independent of the ph whereas that of ipad took place only at low ph. to support the data obtained with the purified proteins, we designed a system ... | 2000 | 10971588 |
| diversion of cytoskeletal processes by shigella during invasion of epithelial cells. | shigella, the causative agent of bacillar dysentery, invades colonic epithelial cells and moves intracellularly to spread from cell to cell. the processes of shigella entry, determined by the ipa proteins, and of actin-based motility, dependent on the icsa/virg protein, represent different levels of bacterial manipulation of the cell cytoskeleton. | 2000 | 10955962 |
| attenuated shigella flexneri 2a vaccine strain cvd 1204 expressing colonization factor antigen i and mutant heat-labile enterotoxin of enterotoxigenic escherichia coli. | a multivalent live oral vaccine against both shigella spp. and enterotoxigenic escherichia coli (etec) is being developed based on the hypothesis that protection can be achieved if attenuated shigellae express etec fimbrial colonization factors and genetically detoxified heat-labile toxin from a human etec isolate (lth). two detoxified derivatives of lth, lthk63 and lthr72, were engineered by substitution-serine to lysine at residue 63, or lysine to arginine at residue 72. the genes encoding the ... | 2000 | 10948101 |
| supramolecular structure of the shigella type iii secretion machinery: the needle part is changeable in length and essential for delivery of effectors. | we investigated the supramolecular structure of the shigella: type iii secretion machinery including its major components. our results indicated that the machinery was composed of needle and basal parts with respective lengths of 45.4 +/- 3.3 and 31.6 +/- 0.3 nm, and contained mxid, mxig, mxij and mxih. spa47, encoding a putative f(1)-type atpase, was required for the secretion of effector proteins via the type iii system and was involved in the formation of the needle. the spa47 mutant produced ... | 2000 | 10921870 |
| synthesis and antimicrobial activity of 4-carbethoxymethyl-2-[(alpha-haloacyl)amino] thiazoles and 5-nonsubstituted/substituted 2-[(4-carbethoxymethylthiazol-2-yl)imino]-4-thiazolidinones. | 4-carbethoxymethyl-2-[(chloroacetyl/alpha-chloropropionyl/al pha- bromobutyryl/alpha-chloro-(alpha-phenylacetyl)amino]thiazoles (i-iv) were synthesized by reacting 4-carbethoxymethyl-2-aminothiazole with chloroacetyl chloride, alpha-chloropropionyl chloride, alpha-bromobutyryl bromide and alpha-chloro-alpha-phenylacetyl chloride, respectively. furthermore, i-iv were refluxed with ammonium thiocyanate to give 2-[(4-carbethoxymethylthiazol-2-yl)imino]-4-thiazolidinones (v-viii). v was refluxed wit ... | 2000 | 10918953 |
| [diarrheal disease among caregivers at children's day-care centers. a retrospective and seroepidemiologic study]. | diarrheal disease tends to spread from infected children to their families. due to the increased risk of exposure, children's caregivers in day-care centers may have a higher incidence of diarrhea, particularly when caring for very young children. we therefore examined the incidence of diarrhea and antibodies to shigella among caregivers in day-care centers, according to age groups of children in their care (< 18, 18-34, and > 35 months) and in comparison with the general population. 2 studies w ... | 1999 | 10914170 |
| a macrophage invasion mechanism for mycobacteria implicating the extracellular domain of cd43. | we studied the role of cd43 (leukosialin/sialophorin), the negatively charged sialoglycoprotein of leukocytes, in the binding of mycobacteria to host cells. cd43-transfected hela cells bound mycobacterium avium, but not salmonella typhimurium or shigella flexneri. quantitative bacteriology showed that macrophages (m(phi)) from wild-type mice (cd43(+/+)) bound m. avium, mycobacterium bovis (bacillus calmette-guérin), and mycobacterium tuberculosis (strain h37rv), whereas m(phi) from cd43 knockout ... | 2000 | 10899905 |
| beta-lactamases in shigella flexneri isolates from hong kong and shanghai and a novel oxa-1-like beta-lactamase, oxa-30. | ninety-one ampicillin-resistant shigella flexneri strains from hong kong and shanghai were studied for production of beta-lactamases. tem-1-like and oxa-1-like enzymes were identified in 21 and 79% of the strains, respectively, by isoelectric focusing (ief). no difference in the pattern of beta-lactamase production was found between strains from hong kong and shanghai. four ribotypes were detected. over 88% of oxa-producing strains had the same ribotype. all tem-1-like strains harbored a plasmid ... | 2000 | 10898672 |
| amino acid substitutions in a variant of imp-1 metallo-beta-lactamase. | in the course of surveying for the carbapenem-hydrolyzing metallo-beta-lactamase gene bla(imp) in pathogenic bacteria by the pcr method, we detected a gene encoding a variant metallo-beta-lactamase, designated imp-3, which differed from imp-1 by having low hydrolyzing activity for penicillins and carbapenems. pcr product direct sequencing of a 2.2-kb segment revealed that the gene bla(imp-3) was located on a cassette inserted within a class i integron in the pms390 plasmid. the 741-bp nucleotide ... | 2000 | 10898670 |
| invasive shigella flexneri activates nf-kappa b through a lipopolysaccharide-dependent innate intracellular response and leads to il-8 expression in epithelial cells. | the pathogenesis of shigella flexneri infection centers on the ability of this organism to invade epithelial cells and initiate an intense inflammatory reaction. because nf-kappa b is an important transcriptional regulator of genes involved in inflammation, we investigated the role of this transcription factor during s. flexneri infection of epithelial cells. infection of hela cells with invasive s. flexneri induced nf-kappa b dna-binding activity; noninvasive s. flexneri strains did not lead to ... | 2000 | 10878365 |
| [shigellosis and other acute intestinal infections in the republic of tajikistan: the epidemiological patterns]. | acute enteric infections (aei), including shigellosis, are characterized by their extremely wide spread in tajikistan. their hyperendemicity is due to a high activity of the water route of transmission under the conditions of hot climate. the morbidity level of aei both in the republic as a whole and in its individual territories has been found to directly depend on the degree of the potential epidemiological danger of the water supply system, as well as on the quality of water used by the popul ... | 1999 | 10876848 |
| the pathogenesis of shigella flexneri infection: lessons from in vitro and in vivo studies. | shigella flexneri is a gram-negative facultatively intracellular pathogen responsible for bacillary dysentery in humans. more than one million deaths occur yearly due to infections with shigella spp. and the victims are mostly children of the developing world. the pathogenesis of shigella centres on the ability of this organism to invade the colonic epithelium where it induces severe mucosal inflammation. much information that we have gained concerning the pathogenesis of shigella has been deriv ... | 2000 | 10874731 |
| inorganic polyphosphate: a molecule of many functions. | inorganic polyphosphate (poly p) is a chain of tens or many hundreds of phosphate (pi) residues linked by high-energy phosphoanhydride bonds. despite inorganic polyphosphate's ubiquity--found in every cell in nature and likely conserved from prebiotic times--this polymer has been given scant attention. among the reasons for this neglect of poly p have been the lack of sensitive, definitive, and facile analytical methods to assess its concentration in biological sources and the consequent lack of ... | 1999 | 10872445 |
| profilin is required for sustaining efficient intra- and intercellular spreading of shigella flexneri. | the ability of shigella to mediate actin-based motility within the host cell is a prominent pathogenic feature of bacillary dysentery. the ability is dependent on the interaction of virg with neural wiskott-aldrich syndrome protein (n-wasp), which in turn mediates recruitment of arp2/3 complex and several actin-related proteins. in the present study, we show that profilin i is essential to the rapid movement of shigella in epithelial cells, for which the capacity of profilin to interact with g-a ... | 2000 | 10867004 |
| characterization of the genes encoding the shea haemolysin in escherichia coli o157:h7 and shigella flexneri 2a. | 2000 | 10865950 | |
| [a case report: a small outbreak of flexner dysentery in a kindergarten]. | 1999 | 10852012 | |
| disease-dependent changes in t-cell populations in patients with shigellosis. | in shigellosis, bacterial infection is associated with an extensive inflammation of the rectal mucosa, resulting in bloody dysentery. the role of t-cell-mediated pro-inflammatory mechanisms has been implicated in this process, but the specific role of t-cell subsets is still not well understood. in this study we attempted to identify the changes in t-cell populations in patients with shigellosis during the disease course. the t-cell subset distribution was analyzed by immunohistochemistry in the ... | 2000 | 10843411 |
| caspase-1 activation of il-1beta and il-18 are essential for shigella flexneri-induced inflammation. | caspases are intracellular proteases that mediate mammalian cell apoptosis. caspase-1 (casp-1) is a unique caspase because it activates the proinflammatory cytokines interleukin (il)-1beta and il-18. shigella flexneri, the etiological agent of bacillary dysentery, induces macrophage apoptosis, which requires casp-1 and results in the release of mature il-1beta and il-18. here we show that casp-1(-/-) mice infected with s. flexneri do not develop the acute inflammation characteristic of shigellos ... | 2000 | 10843390 |
| rho family gtpase cdc42 is essential for the actin-based motility of shigella in mammalian cells. | shigella, the causative agent of bacillary dysentery, is capable of directing its movement within host cells by exploiting actin dynamics. the virg protein expressed at one pole of the bacterium can recruit neural wiskott-aldrich syndrome protein (n-wasp), a downstream effector of cdc42. here, we show that cdc42 is required for the actin-based motility of shigella. microinjection of a dominant active mutant cdc42, but not rac1 or rhoa, into swiss 3t3 cells accelerated shigella motility. in add-b ... | 2000 | 10839806 |
| matrix-assisted laser desorption/ionization time-of-flight mass spectrometric detection of bacterial biomarker proteins isolated from contaminated water, lettuce and cotton cloth. | matrix-assisted laser desorption/ionization time-of-flight (maldi-tof) mass spectra of bacterial proteins were obtained from water, lettuce and cloth samples contaminated with shigella flexneri, escherichia coli, and aeromonas hydrophila. spectra were obtained using proteins directly isolated from water (or water used for rinsing samples) without culturing the bacteria. for s. flexneri and e. coli, two marker ions for specific proteins associated with a virulence-related property (acid resistanc ... | 2000 | 10825256 |
| curli loci of shigella spp. | an unstable chromosomal element encoding multiple antibiotic resistance in shigella flexneri serotype 2a was found to include sequences homologous to the csg genes encoding curli in escherichia coli and salmonella enterica serovar typhimurium. as curli have been implicated in the virulence of serovar typhimurium, we investigated the csg loci in all four species of shigella. dna sequencing and pcr analysis showed that the csg loci of a wide range of shigella strains, of diverse serotypes and diff ... | 2000 | 10816548 |
| interaction of shigella flexneri ipac with model membranes correlates with effects on cultured cells. | invasion of enterocytes by shigella flexneri requires the properly timed release of ipab and ipac at the host-pathogen interface; however, only ipac has been found to possess quantifiable activities in vitro. we demonstrate here that when added to cultured cells, purified ipac elicits cytoskeletal changes similar to those that occur during shigella invasion. this ipac effect may correlate with its ability to interact with model membranes at physiological ph and to promote entry by an ipac mutant ... | 2000 | 10816532 |
| shigella flexneri ipah(7.8) facilitates escape of virulent bacteria from the endocytic vacuoles of mouse and human macrophages. | the behavior of shigella flexneri ipah mutants was studied in human monocyte-derived macrophages (hmdm), in 1-day-old human monocytes, and in j774 mouse macrophage cell line. in hmdm, strain pwr700, an ipah(7.8) deletion mutant of s. flexneri 2a strain 2457t, behaved like the wild-type strain 2457t. this strain caused rapid host cell death by oncosis, and few bacterial cfu were recovered after incubation in the presence of gentamicin as previously described for 2457t-infected hmdm. however, anal ... | 2000 | 10816519 |
| a high incidence of shigella-induced arthritis in a primate species: major histocompatibility complex class i molecules associated with resistance and susceptibility, and their relationship to hla-b27. | the human major histocompatibility complex (mhc) class i gene, hla-b27, is a strong risk factor for susceptibility to a group of disorders termed spondyloarthropathies. rodents that express hla-b27 develop spondyloarthropathies, implicating hla-b27 in the etiology of these disorders. to determine whether an hla-b27-like molecule was associated with spondyloarthropathies in nonhuman primates, we analyzed the mhc class i cdnas expressed in a cohort of rhesus macaques that developed reactive arthri ... | 2000 | 10803844 |
| detection of pcr products of the ipah gene from shigella and enteroinvasive escherichia coli by enzyme linked immunosorbent assay. | pcr techniques applied to diarrheal stools reliably diagnose shigella and enteroinvasive escherichia coli (eiec) infections. identification of pcr products using agarose gel electrophoresis (age) and hybridization with dna probes has several shortcomings. automated methods of identifying pcr products that process larger numbers of specimens can facilitate epidemiologic studies and standardize results. in this study, we used elisa following pcr to detect ipah gene sequences of shigella and eiec f ... | 2000 | 10794934 |
| complete nucleotide sequence of tn10. | the complete nucleotide sequence of tn10 has been determined. the dinucleotide signature and percent g+c of the sequence had no discontinuities, indicating that tn10 constitutes a homogeneous unit. the new sequence contained three new open reading frames corresponding to a glutamate permease, repressors of heavy metal resistance operons, and a hypothetical protein in bacillus subtilis. the glutamate permease was fully functional when expressed, but tn10 did not protect escherichia coli from the ... | 2000 | 10781570 |
| the seasonal variation in the microbial agents implicated in the etiology of diarrheal diseases among children in lao people's democratic republic. | during 1994-1995, the etiological structure of children's diarrhea was monitored in outpatients at mahosot hospital, vientiane, lao pdr. of the 191 children studied, 42% had stool specimens positive for enteropathogens; 22% had rotavirus, 21.5% enteropathogenic e. coli, 4.7% shigella flexneri, 2.9% campylobacter jejuni, 2.1% shigella sonnei, and 0.5% each of giardia intestinalis and entamoeba histolytica. no vibrio cholerae and salmonella spp. was detected in this monitoring. in children under f ... | 1999 | 10774703 |
| the shda gene is restricted to serotypes of salmonella enterica subspecies i and contributes to efficient and prolonged fecal shedding. | little is known about factors which enable salmonella serotypes to circulate within populations of livestock and domestic fowl. we have identified a dna region which is present in salmonella serotypes commonly isolated from livestock and domestic fowl (s. enterica subspecies i) but absent from reptile-associated salmonella serotypes (s. bongori and s. enterica subspecies ii to vii). this dna region was cloned from salmonella serotype typhimurium and sequence analysis revealed the presence of a 6 ... | 2000 | 10768965 |
| the siga gene which is borne on the she pathogenicity island of shigella flexneri 2a encodes an exported cytopathic protease involved in intestinal fluid accumulation. | in this study, the siga gene situated on the she pathogenicity island of shigella flexneri 2a was cloned and characterized. sequence analysis showed that siga encodes a 139.6-kda protein which belongs to the spate (serine protease autotransporters of enterobacteriaceae) subfamily of autotransporter proteins. the demonstration that siga is autonomously secreted from the cell to yield a 103-kda processed form and possesses a conserved c-terminal domain for export from the cell were consistent with ... | 2000 | 10768931 |
| comparison of six dose-response models for use with food-borne pathogens. | food-related illness in the united states is estimated to affect over six million people per year and cost the economy several billion dollars. these illnesses and costs could be reduced if minimum infectious doses were established and used as the basis of regulations and monitoring. however, standard methodologies for dose-response assessment are not yet formulated for microbial risk assessment. the objective of this study was to compare dose-response models for food-borne pathogens and determi ... | 1999 | 10765449 |
| the stability region of the large virulence plasmid of shigella flexneri encodes an efficient postsegregational killing system. | the large virulence plasmid pmysh6000 of shigella flexneri contains a determinant that is highly effective in stabilizing otherwise unstable plasmids in escherichia coli. expression of two small contiguous genes, mvpa and mvpt (formerly termed stborf1 and stborf2), was shown to be sufficient for stability. mutations in mvpt abolished plasmid stability, and plasmids expressing only mvpt killed the cells unless mvpa was supplied from a separate plasmid or from the host chromosome. when replication ... | 2000 | 10762240 |
| [erythromycin sensitivity of shigella flexneri and s. sonnei]. | 2000 | 10756447 | |
| [antimicrobial resistance of shigella spp. in córdoba, argentina, during the period 1990-1997]. | this study analyzed the evolution of antimicrobial resistance in 771 isolates of shigella spp. obtained from a total of 9,195 feces cultures done between 1990 and 1997 in a children's hospital in córdoba, argentina. s. flexneri, which was responsible for 73% of the shigella infections, was the species with the greatest resistance. the frequency of s. flexneri resistance to the three antibiotics most used (ampicillin, trimethoprim-sulfamethoxazole, and chloramphenicol) increased from 10% in 1990 ... | 2000 | 10748662 |
| antagonistic effect of lactobacillus acidophilus, saccharomyces boulardii and escherichia coli combinations against experimental infections with shigella flexneri and salmonella enteritidis subsp. typhimurium in gnotobiotic mice. | lactobacillus acidophilus, saccharomyces boulardii and escherichia coli are probiotic strains used individually to protect against enteropathogenic agents. in order to determine if a synergistic effect of the individual protective mechanisms ordinarily attributed to each of these biotherapeutic agents is possible, we orally administered lact. acidophilus h2b20, s. boulardii and e. coli emo (lse) to germfree mice. ten days after colonization of the digestive tract, groups of animals associated (e ... | 2000 | 10747216 |
| antimicrobial resistance trends in shigella serogroups isolated in israel, 1990-1995. | from a total of 31319 shigella strains isolated in israel between 1990 and 1996, 17574 were sent to the national shigella reference center for typing. of these, 15287 were identified as shigella sonnei, 1833 as shigella flexneri, 327 as shigella boydii and 127 as shigella dysenteriae. in all, 4395 strains were tested for sensitivity to ampicillin, trimethoprim-sulfamethoxazole, tetracycline, chloramphenicol, nalidixic acid and ofloxacin. all strains tested were sensitive to ofloxacin, and only t ... | 2000 | 10746496 |
| shigella actin-based motility in the presence of truncated vinculin. | mounting evidence supports the role of truncated vinculin in the intracellular actin-based motility of shigella flexneri. vinculin's role was recently questioned by goldberg [1997: cell motil cytoskeleton 37:44-53] who observed shigella motility in mouse embryonal carcinoma 5.51 cells, a genetically modified cell line that reputedly lacked vinculin. that challenge implicitly relied on the assumption that 5.51 cells had no detectable vinculin polypeptide and lacked full-length vinculin mrna. desp ... | 2000 | 10744860 |
| clostridium difficile recombinant toxin a repeating units as a carrier protein for conjugate vaccines: studies of pneumococcal type 14, escherichia coli k1, and shigella flexneri type 2a polysaccharides in mice. | unlike the native protein, a nontoxic peptide (repeating unit of the native toxin designated raru) from clostridium difficile toxin a (cdta) afforded an antigen that could be bound covalently to the surface polysaccharides of pneumococcus type 14, shigella flexneri type 2a, and escherichia coli k1. the yields of these polysaccharide-protein conjugates were significantly increased by prior treatment of raru with succinic anhydride. conjugates, prepared with raru or succinylated (rarusucc), were a ... | 2000 | 10722615 |
| emergence of antimicrobial-resistant shigellosis in oregon. | ampicillin and trimethoprim-sulfamethoxazole (tmp-smz) are currently considered acceptable empirical therapy for shigellosis in developed countries. however, there are few recently reported studies on antimicrobial resistance among shigellae isolated in the united states. we examined the epidemiology of shigellosis and the antimicrobial susceptibility of shigella species isolated in oregon from july 1995 through june 1998. of 430 isolates, 410 were identified to the species level: shigella sonne ... | 2000 | 10722437 |
| construction of an efficient expression system for agrobacterium tumefaciens based on the coliphage t5 promoter. | a versatile expression vector utilizing a promoter of coliphage t5, p(n25) (gentz and bujard, 1985. j. bacteriol. 164, 70-77) and a derivative of the incw broad-host-range plasmid pjb20 (beaupré et al., 1997. j. bacteriol. 179, 78-89) has been developed. this vector successfully expresses virulence proteins of agrobacterium tumefaciens encoded by virg and a mutant allele of vira, vira (delta1-284, g665d) in escherichia coli as well as in a. tumefaciens. the signal transduction proteins vira (del ... | 2000 | 10721702 |
| survival of some species of salmonella and shigella in mukumbi, a traditional zimbabwean wine. | mukumbi is a traditional zimbabwean wine prepared from a fruit called mapfura by the shona people of zimbabwe and amaganu by the ndebele. the majority of people in africa call the tree marula (sclerocarya birrea subspecies caffra). the survival of salmonella group b, salmonella enteritidis, shigella sonnei and shigella flexneri in unfermented and fermented mapfura (marula) juice (mukumbi) was investigated. it was found that within 30 min of inoculation, there were no longer any viable pathogens ... | 1999 | 10719586 |
| deltaguaba attenuated shigella flexneri 2a strain cvd 1204 as a shigella vaccine and as a live mucosal delivery system for fragment c of tetanus toxin. | the deltaguaba shigella flexneri 2a vaccine candidate, cvd 1204, was evaluated as a delivery system for the non-toxic c-terminal of tetanus toxin (fragment c), either as a polypeptide expressed in the bacteria or as a dna vaccine. cvd 1204 was transformed with plasmid ptetnir15 which encodes the fragment c gene (tetc) under the control of the inducible prokaryotic nir15 promoter or a dna vaccine plasmid pcdna3tetc which encodes tetc under the eukaryotic hcmv promoter. guinea pigs immunised intra ... | 2000 | 10717338 |
| the development of a facs-based strategy for the isolation of shigella flexneri mutants that are deficient in intercellular spread. | in the disease course of bacillary dysentery, pathogenic shigella flexneri invade colonic epithelial cells and spread both within and between host cells. the ability to spread intercellularly allows the organism to infect an entire epithelial layer without significant contact with the extracellular milieu. using fluorescence activated cell sorter (facs)-based technology, we developed a rapid and powerful selection strategy for the isolation of s. flexneri mutants that are unable to spread from c ... | 2000 | 10712681 |
| serogroup prevalence of shigellae in bombay. | prevalence of shigellae serotypes in bombay was studied from june 1988 to may 1991. a total of 2758 faecal specimens were collected from paediatric patients (< 12 yrs) with acute gastroenteritis. a total of 90 shigella were isolated giving the isolation rate of 3.2%. shigella flexneri was the predominant serogroup (73.3%) followed by shigella dysenteriae (16.6%). all the isolates were sensitive to nalidixic acid. eighty percent of the shigellae were multidrug resistant. present data were compare ... | 1995 | 10707731 |
| [the role of the structural components of bacterial lipopolysaccharide in its inductive immunosuppressive activity]. | the inductive immunosuppressive activity of lipopolysaccharides (lps) and structural parts (o-chains,cor,lipid a) obtained from bacteria of the genus shigella and escherichia coli was studied. lps preparations were extracted by phenol-water method. its structural components were obtained by the acetic acid hydrolysis and gel filtration. it has been shown that all these preparations did not change the level of delayed type hypersensitivity (dth) to test-antigen in mice in the case of intraperiton ... | 1999 | 10707531 |
| blockade of cd14 increases shigella-mediated invasion and tissue destruction. | shigella is a diarrheal pathogen that causes disease through invasion of the large intestinal mucosa. the endotoxin of the invading bacterium may play a key role in the disease process by causing inflammation and tissue injury during infection. earlier studies have shown that various animal species lacking functional cd14 were protected against endotoxin-mediated shock. rabbits experimentally infected with shigella were used to test the hypothesis that blockade of endotoxin-induced cell activati ... | 2000 | 10706713 |
| cell adhesion molecules in the pathogenesis of and host defence against microbial infection. | eukaryotic cell adhesion molecules (cams) are used by various cells and extracellular molecules in host defence against infection. they are involved in many processes including recognition by circulating phagocytes of a site of inflammation, transmigration through the endothelial barrier, diapedesis through basement membrane and extracellular matrix, and release of effector mechanisms at the infected site. cams involved in leucocyte-endothelial cell interaction include the selectins, integrins, ... | 1999 | 10694943 |
| transfer rna modification, temperature and dna superhelicity have a common target in the regulatory network of the virulence of shigella flexneri: the expression of the virf gene. | full expression of the virulence genes of shigella flexneri requires the presence of two modified nucleosides in the trna [queuosine, q34, present in the wobble position (position 34) and 2-methylthio-n6-isopentenyladenosine (ms2i6a37, adjacent to and 3' of the anticodon)]. the synthesis of these two nucleosides depends on the products of the tgt and miaa genes respectively. we have shown that the intracellular concentration of the virulence-related transcriptional regulator virf is reduced in t ... | 2000 | 10692168 |
| evaluation of antibacterial activity of asparagus racemosus willd. root. | different concentrations (50, 100, 150 microg/ml) of the methanol extract of the roots of asparagus racemosus willd. showed considerable in vitro antibacterial efficacy against escherichia coli, shigella dysenteriae, shigella sonnei, shigella flexneri, vibrio cholerae, salmonella typhi, salmonella typhimurium, pseudomonas putida, bacillus subtilis and staphylococcus aureus. the effects produced by the methanol extract were compared with chloramphenicol. | 2000 | 10685109 |
| induction of necrosis in human neutrophils by shigella flexneri requires type iii secretion, ipab and ipac invasins, and actin polymerization. | infection by shigella flexneri is characterized by infiltration of neutrophils in the intestinal mucosa and by a strong inflammatory reaction. although neutrophils are constitutively programmed to die by apoptosis, we show that isolated human neutrophils undergo necrosis 2 h after infection with virulent s. flexneri strain m90t but not with the virulence plasmid-cured strain bs176. this was demonstrated by the release of azurophil granule proteins concomitant with the release of lactate dehydrog ... | 2000 | 10678940 |
| shigella flexneri 2a strain cvd 1207, with specific deletions in virg, sen, set, and guaba, is highly attenuated in humans. | a phase 1 clinical trial was conducted among 35 healthy adult volunteers to evaluate the safety, immunogenicity, and shedding of different doses of cvd 1207, a live attenuated shigella flexneri 2a vaccine candidate with specific deletion mutations in virg, sen, set, and guaba. cvd 1207 retains the ability to invade epithelial cells but cannot effectively spread intercellularly after invasion (deltavirg), does not produce enterotoxin (deltasen and deltaset), and has limited proliferation in vivo ... | 2000 | 10678904 |
| e. coli hemolysin e (hlye, clya, shea): x-ray crystal structure of the toxin and observation of membrane pores by electron microscopy. | hemolysin e (hlye) is a novel pore-forming toxin of escherichia coli, salmonella typhi, and shigella flexneri. here we report the x-ray crystal structure of the water-soluble form of e. coli hlye at 2.0 a resolution and the visualization of the lipid-associated form of the toxin in projection at low resolution by electron microscopy. the crystal structure reveals hlye to be the first member of a new family of toxin structures, consisting of an elaborated helical bundle some 100 a long. the elect ... | 2000 | 10660049 |
| identification of a novel genetic locus that is required for in vitro adhesion of a clinical isolate of enterohaemorrhagic escherichia coli to epithelial cells. | enterohaemorrhagic escherichia coli (ehec) are food-borne intestinal pathogens with a low infectious dose. adhesion of some ehec strains to epithelial cells is attributed, in part, to intimin, but other factors may be required for the intestinal colonizing ability of these bacteria. in order to identify additional adherence factors of ehec, we generated transposon mutants of a clinical ehec isolate of serotype o111:h-, which displayed high levels of adherence to cultured chinese hamster ovary (c ... | 2000 | 10652089 |
| effect of erythromycin on shigella infection of caco-2 cells. | erythromycin (em), one of the macrolides, shows a dose-dependent effect on shigella flexneri invasion of caco-2 cells even at concentrations less than the minimum inhibitory concentration (submic). ls13, a strain of s. flexneri 1b, invaded caco-2 cells in vitro. when the strain was treated with submic of em, the invasion efficiency decreased. the carrier rate of the invasion plasmid containing virulence genes was reduced by em treatment, as determined by the colony pigmentation test on congo red ... | 2000 | 10640609 |
| serotype-converting bacteriophages and o-antigen modification in shigella flexneri. | o-antigen modification (serotype conversion) in shigella flexneri, which is an important virulence determinant, is conferred by temperate bacteriophages. several serotype-converting phages have been isolated and preliminary characterization has identified the genes involved in o-antigen modification, and has also provided insight into the molecular biology of these phages. | 2000 | 10637639 |
| [functional heterogeneity of polymorphonuclear leukocytes population in peripheral blood of patients with acute dysentery]. | to study chemiluminescence (cl) of polymorphonuclear neutrophils (pmnl) in peripheral blood of patients with acute mild and moderate dysentery caused by shig. flexneri in response to re- and s-chemotype lipopolysaccharide (lps) sh. flexneri and agonists fmlp, pma and oz. | 1999 | 10626327 |
| i-ceui fragment analysis of the shigella species: evidence for large-scale chromosome rearrangement in s. dysenteriae and s. flexneri. | i-ceui fragments of four shigella species were analyzed to investigate their taxonomic distance from escherichia coli and to collect substantiated evidence of their genetic relatedness because their ribosomal rna sequences and similarity values of their chromosomal dna/dna hybridization had proved their taxonomic identity. i-ceui digestion of genomic dnas yielded seven fragments in every species, indicating that all the shigella species contained seven sets of ribosome rna operons. to determine ... | 2000 | 10612738 |
| interaction of enteropathogenic or enterohemorrhagic escherichia coli with hela cells results in translocation of cortactin to the bacterial adherence site. | infection of cultured hela epithelial cells with enteropathogenic escherichia coli (epec) or enterohemorrhagic e. coli (ehec) o157:h7 results in accumulation of cortactin under the adherent bacteria. tyrosine phosphorylation of cortactin is not induced following hela cell infection with ehec or epec, contrary to what has been reported to occur with shigella flexneri. | 2000 | 10603412 |
| hiv infection as a risk factor for shigellosis. | we investigated cases of shigellosis in san francisco and alameda counties identified during 1996 by active laboratory surveillance to assess the role of hiv infection as a risk factor for shigellosis. dramatically elevated rates of shigellosis in hiv-infected persons implicate hiv infection as an important risk factor for shigellosis in san francisco. | 1999 | 10603219 |
| src tyrosine kinase activity down-regulates rho-dependent responses during shigella entry into epithelial cells and stress fibre formation. | invasion of epithelial cells by shigella, the causative agent of bacillary dysentery, is dependent upon the formation of characteristic membrane ruffles that engulf the bacteria in a macropinocytic-like process. we show here that cdc42 and rac gtpases, but not rho;, are critical for actin polymerisation, whereas rho; is necessary for the recruitment of ezrin and src at the site of entry. remarkably, cells expressing constitutively active src did not show ezrin recruitment at shigella entry foci. ... | 2000 | 10591626 |
| adhesion and invasion of a mutant shigella flexneri to an eukaryotic cell line in absence of the 220-kb virulence plasmid. | a shigella flexneri strain, cured of the large 220-kb virulence plasmid, expresses adhering and invading ability in confluent monolayers of hela cells similar to its parent strain. invasion by both the parent and the cured strains resulted in alteration of the monomeric actin (g) in the total actin pool of hela cells. other indicators of invasive characteristics of virulent shigella strains such as production of keratoconjunctivitis in guinea pig eye in vivo, congo red binding and expression of ... | 1999 | 10585548 |
| dsba: a protein-folding catalyst contributing to bacterial virulence. | dsba, a periplasmic thiol:disulphide oxidoreductase, catalyses the folding of various factors, among which are virulence determinants or the components of type iii secretory machinery. it is also necessary for intracellular survival and cell-to-cell spread of the intracellular pathogen shigella flexneri. | 1999 | 10580278 |
| [monitoring antibiotic resistance in argentina. the whonet program, 1995-1996]. | the world health organization has implemented a surveillance program for antimicrobial resistance that is known as whonet. in argentina the program was developed through a network of 23 public and private hospitals that participate in national and international quality-control programs. between january 1995 and december 1996, the antimicrobial susceptibility of 16,073 consecutive clinical isolates was determined, using the recommended standards of the national committee for clinical laboratory s ... | 1999 | 10572473 |
| ikappabepsilon-deficient mice: reduction of one t cell precursor subspecies and enhanced ig isotype switching and cytokine synthesis. | three major inhibitors of the nf-kappab/rel family of transcription factors, ikappabalpha, ikappabbeta, and ikappabepsilon, have been described. to examine the in vivo role of the most recently discovered member of the ikappab family, ikappabepsilon, we generated a null allele of the murine ikappabepsilon gene by replacement of all coding sequences with nlslacz. unlike ikappabalpha nullizygous mice, mice lacking ikappabepsilon are viable, fertile, and indistinguishable from wild-type animals in ... | 1999 | 10570287 |
| identification of a putative salmonella enterica serotype typhimurium host range factor with homology to ipah and yopm by signature-tagged mutagenesis. | the genetic basis for the host adaptation of salmonella serotypes is currently unknown. we have explored a new strategy to identify salmonella enterica serotype typhimurium (s. typhimurium) genes involved in host adaptation, by comparing the virulence of 260 randomly generated signature-tagged mutants during the oral infection of mice and calves. this screen identified four mutants, which were defective for colonization of only one of the two host species tested. one mutant, which only displayed ... | 1999 | 10569754 |
| detection of endotoxins and other pyrogens using human whole blood. | when cells of the immune system, i.e. primarily blood monocytes and macrophages, come into contact with pyrogens (fever-inducing contaminations) they release mediators transmitting the fever reaction through the organism to the thermoregulatory centres of the brain. the new test discussed here exploits this reaction for the detection of pyrogens: human whole blood taken from healthy volunteers is incubated in the presence of the test sample. if there is pyrogen contamination, the endogenous pyro ... | 1999 | 10566786 |
| salmonella typhimurium leucine-rich repeat proteins are targeted to the spi1 and spi2 type iii secretion systems. | salmonellae encode two virulence-associated type iii secretion systems (ttss) within salmonella pathogenicity islands 1 and 2 (spi1 and spi2). two salmonella typhimurium genes, ssph1 and ssph2, that encode proteins similar to the shigella flexneri and yersinia species ttss substrates, ipah and yopm, were identified. ssph1 and ssph2 are proteins containing leucine-rich repeats that are differentially targeted to the spi1 and spi2 ttss. ssph2 transcription was induced within raw264.7 macrophages, ... | 1999 | 10564523 |
| a system for identifying post-invasion functions of invasion genes: requirements for the mxi-spa type iii secretion pathway of shigella flexneri in intercellular dissemination. | invasion and intercellular spread are hallmarks of shigella pathogenicity. invasion of the eukaryotic cell cytosol requires a type iii secretion system (mxi-spa) and its cognate set of secreted ipa invasins. once intracellular, the icsa protein directs a form of actin-based motility that helps to drive intracellular bacterial movement, formation of cellular protrusions and cell-to-cell spread. work in our laboratory has focused on identifying additional factors required for this intercellular fo ... | 1999 | 10564508 |
| actin-based motility of vaccinia virus mimics receptor tyrosine kinase signalling. | studies of the actin-based motility of the intracellular pathogens listeria monocytogenes and shigella flexneri have provided important insight into the events occurring at the leading edges of motile cells. like the bacteria listeria and shigella, vaccinia virus, a relative of the causative agent of smallpox, uses actin-based motility to spread between cells. in contrast to listeria or shigella, the actin-based motility of vaccinia is dependent on an unknown phosphotyrosine protein, but the und ... | 1999 | 10553910 |
| extraintestinal dissemination of salmonella by cd18-expressing phagocytes. | specialized epithelia known as m cells overlying the lymphoid follicles of peyer's patches are important in the mucosal immune system, but also provide a portal of entry for pathogens such as salmonella typhimurium, mycobacterium bovis, shigella flexneri, yersinia enterocolitica and reoviruses. penetration of intestinal m cells and epithelial cells by salmonella typhimurium requires the invasion genes of salmonella pathogenicity island 1 (spi1). spi1-deficient s. typhimurium strains gain access ... | 1999 | 10548107 |
| the tripartite type iii secreton of shigella flexneri inserts ipab and ipac into host membranes. | bacterial type iii secretion systems serve to translocate proteins into eukaryotic cells, requiring a secreton and a translocator for proteins to pass the bacterial and host membranes. we used the contact hemolytic activity of shigella flexneri to investigate its putative translocator. hemolysis was caused by formation of a 25-a pore within the red blood cell (rbc) membrane. of the five proteins secreted by shigella upon activation of its type iii secretion system, only the hydrophobic ipab and ... | 1999 | 10545510 |
| binding of the shigella protein ipaa to vinculin induces f-actin depolymerization. | shigella flexneri, the causative agent of bacillary dysentery, enters into epithelial cells by a macropinocytic process. ipaa, a shigella protein secreted upon cell contact, binds to the focal adhesion protein vinculin and is required for efficient bacterial uptake. ipaa was shown here to bind with high affinity to the n-terminal residues 1-265 of vinculin. using co-sedimentation and solid-phase assays, we demonstrated that binding of ipaa to vinculin strongly increases the association of vincul ... | 1999 | 10545097 |
| analysis of shigella flexneri wzz (rol) function by mutagenesis and cross-linking: wzz is able to oligomerize. | the modal length or degree of polymerization (dp) of the shigella flexneri o-antigen is determined in an unknown manner by the wzz/rol protein. the wzz protein is anchored into the cytoplasmic membrane by two transmembrane domains (tm1 amino acids 32-52; tm2 amino acids 295-315) with the central loop of the protein located in the periplasm. plasmids were constructed encoding hybrid wzz proteins consisting of regions of s. flexneri wzz (wzzsf) and salmonella typhimurium wzz (wzzst). these imparte ... | 1999 | 10540296 |
| native and mutant forms of cholera toxin and heat-labile enterotoxin effectively enhance protective efficacy of live attenuated and heat-killed shigella vaccines. | both native and mutant forms of cholera toxin (ct) and heat-labile enterotoxin (lt) are effective adjuvants for antigens and killed whole-cell preparations. to determine whether these toxin molecules could also boost the immunogenicity and efficacy of live attenuated vaccines directed against shigellosis, the guinea pig keratoconjunctivitis model was used to evaluate the adjuvant effect of these toxin molecules on ecsf2a-3, a deltavirg deltaarod escherichia coli-shigella flexneri 2a hybrid vacci ... | 1999 | 10531238 |
| characterization of pic, a secreted protease of shigella flexneri and enteroaggregative escherichia coli. | we have identified and characterized a secreted protein, designated pic, which is encoded on the chromosomes of enteroaggregative escherichia coli (eaec) 042 and shigella flexneri 2457t. the product of the pic gene is synthesized as a 146.5-kda precursor molecule which is processed at the n and c termini during secretion, allowing the release of a mature protein (109.8 kda) into the culture supernatant. the deduced amino acid sequence of pic shows high homology to autotransporter proteins, parti ... | 1999 | 10531204 |