| population dynamics in the co-culture of shigella flexneri 1b original strain and its antigenic 3b mutant carrying a prophage. | the antigenic mutant shigella flexneri 3b showed selective prevalence when subcultured with the original strain 1b. mathematical analysis of such co-cultures showed that the dynamics of bacterial growth may be described by equations of the lotka-volterra type. the analysis of serial cultivations suggests that parameters of the equations may be realizations of random variables characterizing strains and media. the mutant carries a prophage lethal for the original strain. distinctive features of t ... | 1995 | 8538494 |
| lack of cleavage of icsa in shigella flexneri causes aberrant movement and allows demonstration of a cross-reactive eukaryotic protein. | once in the cytoplasm of mammalian cells, shigella flexneri expresses a motile phenotype caused by polar directional assembly of actin. this process depends on accumulation of icsa (virg), a 120-kda protein with atpase activity, at the pole of the bacterium opposite to that at which ongoing septation occurs. icsa is also secreted into the bacterial supernatant as a 95-kda species, after cleavage at an ssrrass sequence which, when mutagenized, blocks processing. mabf15, an anti-icsa monoclonal an ... | 1996 | 8550200 |
| expression of reca in deinococcus radiodurans. | deinococcus (formerly micrococcus) radiodurans is remarkable for its extraordinary resistance to ionizing and uv irradiation and many other agents that damage dna. this organism can repair > 100 double-strand breaks per chromosome induced by ionizing radiation without lethality or mutagenesis. we have previously observed that expression of d. radiodurans reca in escherichia coli appears lethal. we now find that the reca protein of d. radiodurans is ot detectable in d. radiodurans except in the s ... | 1996 | 8550406 |
| [the selection of a virulent subpopulation of escherichia coli during shigella and salmonella infections in children]. | | 1995 | 8553728 |
| [the antigenic and immunogenic properties of the bivalent strain shigella flexneri-shigella sonnei 1 no. 200]. | | 1995 | 8553752 |
| further characterization of delta aroa delta virg shigella flexneri 2a strain cvd 1203 as a mucosal shigella vaccine and as a live-vector vaccine for delivering antigens of enterotoxigenic escherichia coli. | the use of attenuated delta aroa delta virg shigella flexneri 2a strain cvd 1203 as a live vector for enterotoxigenic escherichia coli (etec) antigens is reported. cvd 1203 alone or expressing colonization factor antigen fimbriae and cs3 fibrillae of etec was given to guinea pigs and mice, orogastrically (o.g.) or intranasally (i.n.). cvd 1203 given i.n. elicited high titers of antilipopolysaccharide (anti-lps) immunoglobulin a (iga) and was protective in guinea pigs against a homologous conjunc ... | 1996 | 8557344 |
| detection and characterization by differential pcr of host eukaryotic cell genes differentially transcribed following uptake of intracellular bacteria. | host eukaryotic cell genes that are differentially transcribed after phagocytosis of various pathogenic and nonpathogenic bacterial cells were identified by a differential pcr (dpcr) system. this dpcr procedure favors detection and isolation of host genes affected at the transcriptional level by selecting for poly(a) tails but differs substantially from reverse transcription-pcr. several unidentified macrophage gene fragments from genes that were either transcriptionally activated or downregulat ... | 1996 | 8557379 |
| mxig, a membrane protein required for secretion of shigella spp. ipa invasins: involvement in entry into epithelial cells and in intercellular dissemination. | entry of shigella flexneri into epithelial cells involves secretory proteins, the ipa proteins, and their dedicated secretion apparatus, the mxi-spa translocon, which is encoded by the mxi and spa operons. we have characterized the mxig gene that is located at the proximal part of the mxi operon. inactivation of mxig abolished lpa secretion, which indicates that mxig is an essential component of the mxi-spa translocon. immunoblotting analysis of membrane fractions suggests that the 42 kda mxig p ... | 1995 | 8559065 |
| microbiological investigation of diarrhoea epidemics among rwandan refugees in zaire. | | 1995 | 8560524 |
| serotype distribution and antimicrobial susceptibility of shigellae isolated from diarrhoeal patients in yangon, myanmar. | in myanmar there is a changing pattern in the prevalence of shigella strains with an increasing antimicrobial resistance, and, thus the serotype prevalence and antibiotic sensitivity pattern of shigellae were studied in 1993. dysenteric stool samples were collected from the laboratory of infectious diseases hospital, yangon during january-june 1993. the shigella isolates were identified by the standard bacteriologic procedures. four hundred and sixty stool samples containing blood and mucous wer ... | 1995 | 8568195 |
| immunogenicity of the shigella flexneri serotype y (sfl 124) vaccine strain expressing cloned glucosyl transferase gene of converting bacteriophage sfx. | the glucosyl transferase gene (gtr) from bacteriophage phage x (sfx) caused partial conversion of serotype y (group antigen 3, 4) to x (group antigen 7, 8) when introduced into a candidate vaccine strain of shigella flexneri serotype y (sfl124). the gtr gene caused conversion of o-antigens but did not eliminate the adsorption of the corresponding phage sfx. the hybrid strain expressing both group antigens 7, 8 and 3, 4 showed 75% protection when immunized guinea pigs were challenged with a wild- ... | 1995 | 8569531 |
| adherence of helicobacter pylori to cultured human gastric carcinoma cells. | to examine the binding activity of helicobacter pylori to cultured gastric epithelial cells using flow cytometry. | 1995 | 8574746 |
| serum antibody to lipopolysaccharide antigens of shigella species among u.s. military personnel deployed to saudi arabia and kuwait during operations desert shield and desert storm. | during operations desert shield and desert storm, u.s. troops were at high risk of diarrheal disease due to shigella spp., particularly shigella sonnei. in order to better understand the serologic response to shigella infection, 830 male u.s. combat troops were evaluated before and after the deployment to saudi arabia and kuwait for immunoglobulin a (iga) and igg anti-shigella lipopolysaccharide (lps) (antibody to s. sonnei form i and shigella flexneri serotypes 1a, 2a, and 3a) in serum. just be ... | 1995 | 8574833 |
| the secreted ipa complex of shigella flexneri promotes entry into mammalian cells. | the bacterial pathogen shigella flexneri causes bacillary dysentery in humans by invading coloncytes. upon contact with epithelial cells, s. flexneri elicits localized plasma membrane projections sustained by long actin filaments which engulf the microorganism. the products necessary for shigella entry include three secretory proteins: ipab, ipac, and ipad. extracellular ipab and ipac associate in a soluble complex, the ipa complex. we have immunopurified this ipa complex on latex beads and foun ... | 1996 | 8577750 |
| construction and evaluation of a virg thya double mutant of shigella flexneri 2a as a candidate live-attenuated oral vaccine. | a virg thya double mutant of shigella flexneri 2a was constructed as a candidate live-attenuated oral vaccine. in the keratoconjunctivitis model it did not provoke any adverse reaction by itself on guinea pigs' eyes and completely protected them from provoking keratoconjunctivitis. when (2.7-4.8) x 10(10) of the vaccine was inoculated intragastrically after 1 day fasting in cynomolgus monkeys three times at weekly intervals, a watery stool was observed at 40% as a side-effect. upon intragastric ... | 1995 | 8578822 |
| a modified shigella volunteer challenge model in which the inoculum is administered with bicarbonate buffer: clinical experience and implications for shigella infectivity. | in the absence of a definitive immunologic correlate of protection against shigellosis, promising shigella vaccine candidates have been selected based on their ability to confer resistance against experimental challenge with wild-type shigella in healthy adult volunteers. a limitation of this model has been the low and often variable attack rate of illness among controls, necessitating repeated inpatient studies to demonstrate statistically significant results. in this study, the shigella challe ... | 1995 | 8578831 |
| shigella lipopolysaccharide antibodies in pediatric populations. | shigellosis is the most common cause of bacterial dysentery. to study the specific immunity to the two major groups causing shigellosis, we assayed antibodies to lipopolysaccharide (lps) by enzyme-linked immunoadsorbent assay to both shigella sonnei and shigella flexneri 2a serotypes in the following populations: (1) women immediately after delivery and their infants to assess the transfer of passive immunity by placenta and the presence of secretory antibodies in breast milk; (2) children of di ... | 1995 | 8584312 |
| evaluation of giardeia kit for giardiasis diagnosis. | giardia lamblia is recognized as one of the most common agents for diarrhea world wide. to date, microscopical examination of stool samples is the gold standard for giardiasis diagnosis. however, intermittence of the giardia cycle and some medications may cause temporary disappearance of cysts from stools, thus giving false negative results. in the present study, we evaluated a commercially available enzyme immunoassay kit (giardeia) for the detection of giardia copro-antigens and compared the r ... | 1995 | 8586858 |
| [species and serovar-distribution, and drug-resistance of shigella strains isolated from imported and domestic cases from 1990 through 1994 in tokyo]. | a total of 446 shigella strains consisting of 336 imported and 110 domestic strains isolated in tokyo from 1990 to 1994 were examined for their species and serovar-distribution, and their drug-resistance. in both imported and domestic strains, s. sonnei was found to be the most prevalent species, followed by s. flexneri. in imported strains, however, the isolation frequency of s. flexneri, s. boydii and s. dysenteriae were higher than that of domestic strains, and the serovar of each species was ... | 1995 | 8586884 |
| the novel nuclear gene dss-1 of saccharomyces cerevisiae is necessary for mitochondrial biogenesis. | a previously unknown nuclear gene dss-1 from saccharomyces cerevisiae was cloned and sequenced. the gene was isolated as a multicopy suppressor of a disruption of the suv-3 gene coding for a dead/h box protein involved in processing and turnover of mitochondrial transcripts. the dss-1 gene codes for a 970 amino-acid protein of molecular weight 111 kda and is necessary for mitochondrial biogenesis. amino-acid sequence analysis indicates the presence of motifs characteristic for escherichia coli r ... | 1995 | 8590460 |
| expression of flagella and motility by shigella. | since the discovery of shigella as the aetiologic agent of acute dysentery almost 100 years ago, this organism has been described as a non-motile and nonflagellated organism that invades the human colonic mucosa. in this study, the production of flagella by prototypic strains of all four shigella species and, moreover, by fresh clinical isolates was demonstrated by electron microscopy. the flagellum of shigella (flash) is approximately 10 microns long and 12-14 nm in diameter and is typically se ... | 1995 | 8596461 |
| osa protein encoded by plasmid psa is located at the inner membrane but does not inhibit membrane association of virb and vird virulence proteins in agrobacterium tumefaciens. | the osa gene of incw plasmid psa encodes a 21-kda protein that completely abolishes the oncogenic activity encoded by virulence genes in agrobacterium tumefaciens. osa is the last gene of a four-gene operon in psa, the expression of which appears to be highly regulated since the osa protein is absent when either psa or the osa operon is present in the agrobacterium cell. when the osa gene alone or together with upstream genes within the operon are expressed under the control of a constitutive pr ... | 1996 | 8598281 |
| surveillance for waterborne-disease outbreaks--united states, 1993-1994. | since 1971, cdc and the u.s. environmental protection agency have maintained a collaborative surveillance system for collecting and periodically reporting data that relate to occurrences and causes of waterborne-disease outbreaks (wbdos). | 1996 | 8600346 |
| recognition of two classes of oligoproline sequences in profilin-mediated acceleration of actin-based shigella motility. | the gram negative rod shigella flexneri uses it surface protein icsa to induce host cell actin assembly and to achieve intracellular motility. yet, the icsa protein lacks the oligoproline sequences found in acta, the surface protein required for locomotion of the gram positive rod listeria monocytogenes. microinjection of a peptide matching the second acta oligoproline repeat (fefpppptde) stops listeria locomotion (southwick, f.s., and d.l. purich. 1994a. proc. natl. acad. sci. usa. 91:5168-5172 ... | 1996 | 8601612 |
| comparative microbicidal activity of synovial fluid on arthritogenic organisms. | there is strong circumstantial evidence to support the concept that local microbial antigens play a key role in the synovitis of reactive arthritis (rea) patients. it is not at all clear whether these antigens reflect the sequelae of previously viable organisms once resident in the joint. to address the microbicidal activity of synovial fluid (sf) we performed quantitative cultures of arthritogenic organisms (salmonella typhimurium, shigella flexneri, klebsiella pneumoniae) and controls (escheri ... | 1996 | 8603538 |
| induction of a local anti-ipac antibody response in mice by use of a shigella flexneri 2a vaccine candidate: implications for use of ipac as a protein carrier. | the capacity of shigella flexneri to act as a delivery system for stimulation of local immunity was investigated by use of an s. flexneri 2a vaccine candidate (sc602). this vaccine strain was constructed by deletion of virulence genes responsible for dissemination (icsa) and survival (iuc:iut) of bacteria within the colonic mucosa. among the most immunogenic s. flexneri 2a proteins inducing a local immunoglobulin a antibody response, the ipac invasion was selected as a potential protein carrier. ... | 1996 | 8606077 |
| changes in the peripheral blood t-cell receptor v beta repertoire in vivo and in vitro during shigellosis. | a sequential activation of t cells in peripheral blood during shigello sis has been observer (d. islam, p.k. bradham, a. a. lindberg, and b. christensson, infect. immun 63:2941-2949, 1995). to further investigate the cellular response during the course of shigella infection, changes in the t-cell receptor (tcr) repertoire in the subsets in blood in patients during shigellosis was that shigella antigens may modulate the function of t cells carrying tcrs capable of recognizing shigella-specific ep ... | 1996 | 8606106 |
| an o-antigen processing function for wzx (rfbx): a promising candidate for o-unit flippase. | o antigen is the major cell surface antigen of gram-negative bacteria, and the genes responsible for its synthesis are located in a single gene cluster. the wzx (rbfx) gene, which is characteristic of the major class of o-antigen gene clusters, encodes a hydrophobic protein with 12 potential transmembrane segments. we demonstrate that a wzx mutant accumulates undecaprenol pyrophosphate-linked o units which appear to be on the cytoplasmic side of the cytoplasmic membrane, suggesting that the wzx ... | 1996 | 8606190 |
| usefulness of ribotyping in a molecular epidemiology study of shigellosis. | ribotyping performed with six restriction endonucleases was used to study the molecular epidemiology of shigellosis in asturias, spain. the series included shigella sonnei from 34 sporadic cases, 3 outbreaks and 3 reference strains, and s. flexneri from sporadic cases and 1 reference strain. the s. sonnei strains were grouped into 5 ribotypes with sal i, 4 with hind iii and pvu ii, 3 with bgl ii and ecor i and 2 with hinc ii (discriminatory index (di) between 0.54 and 0.14); the s. flexneri into ... | 1996 | 8620903 |
| shigellosis in thai children: experience from a rural hospital 1985-1993. | six hundred and ninety-four cases of shigellosis in nakhon nayok hospital from january 1985 to december 1993 were studied to determine epidemiologic and microbiological features. forty-five percent of cases were children under the age of 14 years. the majority of cases were in children under the age of four. the organism was found throughout the year, with peak incidence in june and july. the most common type isolated was shigella flexneri, about 74.43%. only 0.32% of organisms were shigella dys ... | 1995 | 8629073 |
| induction of adherence and degranulation of polymorphonuclear leukocytes: a new expression of the invasive phenotype of shigella flexneri. | in the present study, the ability of shigella flexneri to activate polymorphonuclear neutrophils (pmn) was examined. the invasive serotype 5 strain m90t induced strong pmn adherence, which was dependent on both the multiplicity of infection and the duration of incubation. when tested under the same experimental conditions, the noninvasive strain bs176 (cured of the 220-kb virulence plasmid) was less efficient. indeed, incubation of pmn for 2 h with either m90t or bs176 (multiplicity of infection ... | 1996 | 8641772 |
| interaction of ipa proteins of shigella flexneri with alpha5beta1 integrin promotes entry of the bacteria into mammalian cells. | shigella is a genus of highly adapted bacterial pathogens that cause bacillary dysentery in humans. bacteria reaching the colon invade intestinal epithelial cells by a process of bacterial-directed endocytosis mediated by the ipa proteins: ipab, ipac, and ipad of shigella. the invasion of epithelial cells is thought to be a receptor-mediated phenomenon, although the cellular components of the host that interact with the ipa proteins have not yet been identified. we report here that in a shigella ... | 1996 | 8642302 |
| a klebsiella pneumoniae strain that shares a type-specific antigen with shigella flexneri serotype 6. characterization of the strain and strain and structural studies of the o-antigenic polysaccharide. | a strain of klebsiella pneumoniae was found as the only isolate with pathogenic potential from the stool of a two-year old patient with diarrhoea. a strong serological cross-reactivity with shigella flexneri serotype 6 was demonstrated. the cross-reacting antigens were shown to reside in the cell wall lipopoly-saccharide. studies of the pathogenic potential of the klebsiella strain showed low level of invasion of hep-2 cells. however, tests for adherence to hep-2 cells as well as tests for toxin ... | 1996 | 8647126 |
| dissociation between cytokine mrna expression and protein production in shigellosis. | in our study, infection with shigella dysenteriae type 1 (n = 16) or shigella flexneri in adults (n = 5) was associated with a gradual accumulation of mrna for interleukin (il)-1 beta, tumor necrosis factor (tnf)-alpha, il-6, transforming growth factor-beta, il-10, il-4, tnf-beta, interferon (ifn)-gamma and perforin in the rectal biopsy samples during the convalescent stage of the disease demonstrated by in situ hybridization. in contrast, immunohistochemical staining in rectal tissues of cytoki ... | 1996 | 8647178 |
| sequence and expression analysis of the hrpb pathogenicity operon of xanthomonas campestris pv. vesicatoria which encodes eight proteins with similarity to components of the hrp, ysc, spa, and fli secretion systems. | in this paper we describe the molecular characterization of hrpb, the largest operon in the xanthomonas campestris pv. vesicatoria hrp cluster. the hrpb region encompasses 6 kb and encodes eight putative proteins, seven of which were expressed in escherichia coli. the hrpb3 protein is the only one carrying a signal peptide sequence at the n-terminus and is a putative lipoprotein localized in the outer membrane of x. campestris pv. vesicatoria. the hrpb4 and hrpb8 proteins contain one and five pu ... | 1995 | 8664494 |
| a spontaneous 99-kb chromosomal deletion results in multi-antibiotic susceptibility and an attenuation of contact haemolysis in shigella flexneri 2a. | a tn5-generated mutant (strain s2430) of shigella flexneri 2a (strain ysh6000) exhibited attenuated virulence and, in addition to the tn5 insertion in the sali k fragment of its virulence plasmid, had a 99-kb deletion within its chromosome. unlike its wild-type parent, strain s2430 was susceptible to ampicillin, streptomycin, tetracycline and chloramphenicol. an independent multi-antibiotic susceptible variant of strain ysh6000 had a similar deletion. southern blot analysis of pulsed field elect ... | 1996 | 8667415 |
| a bacterial invasin induces macrophage apoptosis by binding directly to ice. | shigella, the etiological agent of dysentery, kills macrophages by inducing apoptosis. deletion mutants in the invasion invasion plasmid antigen b (ipab) of shigella flexneri are not cytotoxic. here, we localized ipab to the cytoplasm of macrophages infected with s. flexneri. purified ipab induced apoptosis when microinjected into macrophages, indicating that ipab is sufficient to induce apoptosis. using a gst-ipab fusion protein as a ligand in affinity purification, we isolated four ipab bindin ... | 1996 | 8670890 |
| detection and characterization of the flagellar master operon in the four shigella subgroups. | strains in the genus shigella are nonmotile, but they retain some cryptic flagellar operons whether functional or defective (a.tominaga, m. a.-h. mahmoud, t. mukaihara, and m. enomoto, mol. microbiol. 12:277-285, 1994). to disclose the cause of motility loss in shigellae, the presence or defectiveness of the flhd and flhc genes, composing the master operon whose mutation causes inactivation of the entire flagellar regulon, was examined in the four shigella subgroups. the flhd operon cloned from ... | 1996 | 8682772 |
| a glutamate-dependent acid resistance gene in escherichia coli. | stationary-phase cultures of escherichia coli can survive several hours or exposure to extreme acid (ph 2 to 3), a level well below the ph range for growth (ph 4.5 to 9). to identify the genes needed for survival in extreme acid, a microliter screening procedure was devised. colonies from a tn10 transposon pool in e. coli mc4100 were inoculated into buffered luria broth, ph 7.0, in microtiter wells, grown overnight, and then diluted in luria broth, ph 2.5, at 37 degrees c for 2 h. from 3,000 iso ... | 1996 | 8682809 |
| induction of nitric oxide production in mouse macrophages by shiga toxin. | host mediators play an important role in the pathogenesis of shigellosis and shiga toxin toxicity. nitric oxide (no) production in mouse peritoneal macrophages and in the macrophage j744 cell line in response to purified shiga toxin and lipopolysaccharide (lps) from shigella flexneri were studied. shiga toxin induced no production in a dose-dependent manner up to 800 ng/ml. detectable levels of no were present as early as 4 h after induction and continued to increase during 72 h; shiga toxin ind ... | 1996 | 8683558 |
| antibiotic resistance of shigella in monrovia. | twenty shigella strains were isolated from bloody stools, of which 10 had been collected from children. eighty per cent of the shigella isolates were serogrouped as s. flexneri. all 20 shigella strains were susceptible to gentamicin, nalidixic acid and ciprofloxacin. more than 80% were resistant to ampicillin, cotrimoxazole and tetracycline and 65% were resistant to chloramphenicol. ten of 20 shigella isolates showed a quadruple resistance to all four antibiotics. the usefulness of nalidixic aci ... | 1996 | 8685970 |
| the cell biology of infection by intracellular bacterial pathogens. | listeria monocytogenes and shigella flexneri are unrelated bacterial pathogens that have independently evolved similar strategies of survival within an infected host animal. bacteria coming into contact with the surface of an epithelial cell induce cytoskeletal rearrangements resulting in phagocytosis. they then secrete enzymes that degrade the phagosomal membrane, releasing the bacteria into the host cytoplasm. intracytoplasmic bacteria move rapidly, in association with a "comet tail" made up o ... | 1995 | 8689557 |
| analysis of epithelial cell stress response during infection by shigella flexneri. | shigella flexneri-infected macrophage cells undergo an apoptotic-like death as early as one hour after infection (a. zychlinsky, m. c. prévost, and p. j. sansonetti, nature [london] 358:167-168, 1992). to determine the fate of infected epithelial cells, we characterized the viability, morphology, and several metabolic activities of hela cells after treatment with m90t, an invoffve isolate of s. flexneri serotype 5, or bs176, a noninvasive isolate cured of the 220-kb virulence plasmid. using stan ... | 1996 | 8698469 |
| infection of rabbit peyer's patches by shigella flexneri: effect of adhesive or invasive bacterial phenotypes on follicle-associated epithelium. | in order to invade the colonic mucosa, the bacterial pathogen shigella flexneri must find a site of entry. experiments with the rabbit ligated intestinal loop model described here confirm that m cells of the follicle-associated epithelium (fae) that covers lymphoid structures of the peyer's patches represent a major site of entry for invasive microorganisms. in addition, in an isogenic shigella background, expression of an adhesive phenotype, or of an invasive phenotype, is required for bacteria ... | 1996 | 8698505 |
| pathologic study of a rabbit model for shigellosis. | a nonsurgical rabbit model of enteric shigella infection was developed for studying the pathogenesis and immunology of shigellosis and for evaluating shigella vaccine candidates. in this model, rabbits are made susceptible to shigella infection by a pre-inoculation conditioning procedure consisting of a 36-h nonfeeding period, with 250 mg of tetracycline administered in 250 ml of drinking water, 75 mg of cimetidine given intravenously, and two 15-ml doses of 5% sodium bicarbonate given orally im ... | 1996 | 8699822 |
| convulsions in childhood shigellosis and antimicrobial resistance patterns of shigella isolates. | drug resistance patterns of 68 shigella strains were investigated prospectively in kayseri during a period of approximately two years. the resistance was highest with ampicillin (58.8%) followed by co-trimoxazole (50%) and ampicillin-sulbactam (13%). only 2.8 percent of cases were resistant to gentamicin, and all serogroups were sensitive to ceftriaxone. we conclude that in children with severe shigellosis, treatment with ceftriaxone is effective and better than ampicillin and co-trimoxazole for ... | 1996 | 8701482 |
| functional analysis of shigella virg domains essential for interaction with vinculin and actin-based motility. | the virg (icsa) protein of shigella is required for recruitment of host actin filament (f-actin) by intracellularly motile bacteria. an n-terminal 80-kda virg portion (alpha-domain) is exposed on the bacterial surface, while the following c-terminal 37-kda portion (beta-core) is embedded in the outer membrane. here, we report that the surface exposed alpha-domain of virg possesses two distinct functional domains; one is the n-terminal two-thirds portion of the alpha-domain which is required for ... | 1996 | 8702989 |
| survival of shigella flexneri in artificial aquatic environment: effects of different physicochemical stress factors. | survival of bacteria in aquatic environment is influenced by the prevailing physicochemical characteristics of water. a study was carried out to assess the effects of temperature, ph, and salinity of water on the survival of shigella flexneri in laboratory microcosms. survival of s. flexneri was assessed by viable counts of shigella on macconkey agar plates. at ph 7.0 and temperature of 4 degrees c, s. flexneri survived longer in 0.5% salinity than in salt-free distilled water, while at ph 7.0 a ... | 1996 | 8708331 |
| a role for bacteriophages in the evolution and transfer of bacterial virulence determinants. | a virulence-associated region in the genome of dichelobacter nodosus has been shown to contain an integrase gene which is highly related to the integrases of shigella flexneri phage sf6 and coliphages p4 and phi r73, together with open reading frames (vapb, c and d) related to genes borne on plasmids in neisseria gonorrhoeae, escherichia coli, actinobacillus actinomycetemcomitans and treponema denticola. similar to p4 and phi r73, the vap region is bracketed by putative bacteriophage att sites a ... | 1995 | 8709840 |
| lipopolysaccharide with an altered o-antigen produced in escherichia coli k-12 harbouring mutated, cloned shigella flexneri rfb genes. | cloning of the rfb genes of shigella flexneri 2a into escherichia coli k-12 strain dh1 results in the synthesis of lipopolysaccharides (lps) with an o-antigen chain having type antigen iv and group antigens 3,4. during genetic studies of these rfb genes in e. coli k-12, we observed that strains harbouring plasmids with certain mutations (inversion and transposon insertions) which should have blocked o-antigen synthesis nevertheless still produced lps with o-antigen chains. these lps migrated dif ... | 1995 | 8709841 |
| [bacterial dysentery in 1994]. | | 1996 | 8711142 |
| [detection of resistance to the amoxicillin-clavulamic acid combination in salmonella and shigella]. | to study the emergence of amoxicilline/clavulanate resistance in salmonella and shigella. | 1996 | 8714185 |
| clinical trials of shigella vaccines in israel. | | 1996 | 8718595 |
| stool cultures for shigella spp: improved specificity by using macconkey agar with xylose. | a total of 678 stool specimens were cultured on four different agars: on xylose-lysine-desoxycholate agar (xld), macconkey agar (mac), macconkey agar supplemented with xylose (mac-x), and hektoen enteric agar (he). isolation rates for shigellae were 77% on he, 86% on mac and mac-x, and 91% on xld. the specificities of the media were 61% for mac, 75% for he, and 78% for xld and mac-x. after overnight incubation, mac-x is much easier to read than xld, which requires incubation for at least 22 hour ... | 1996 | 8724396 |
| mechanism of antigenic variation in shigella flexneri bacilli. iii. complement sensitivity of s. flexneri 1b strains and their 3b variants selected either as lac+ recombinants or phage f2 resistant mutants. | several s. flexneri 1b serotype strains of clinical isolation were compared with their 3b serotype variants isolated either as lac+ recombinants from crosses of s. flexneri x e. coli hfr c, or f2-resistant mutants. the studied variants 3b were deprived of type i antigen but acquired type iii antigen. they appeared to be less sensitive to killing action of complement present in normal bovine serum although kinetics of killing and its effectiveness differed between the strains. | 1995 | 8744688 |
| brain edema: an underdiagnosed complication of shigella infection. | | 1995 | 8745030 |
| gene transfer from bacteria to mammalian cells. | transfer of genetic information between phylogenetically remote bacterial genera [1], from bacteria to yeast [2] and from bacteria to plants [3] by plasmid conjugation has been described. however, direct dna transfer from prokaryotes to mammalian cells has not yet been demonstrated. certain bacterial species have evolved the ability to enter mammalian cells by inducing their own internalization [4]. we show that invasive strains of shigella flexneri and escherichia coli, that undergo lysis upon ... | 1995 | 8745635 |
| the unrelated surface proteins acta of listeria monocytogenes and icsa of shigella flexneri are sufficient to confer actin-based motility on listeria innocua and escherichia coli respectively. | listeria monocytogenes and shigella flexneri are two unrelated facultative intracellular pathogens which spread from cell to cell by using a similar mode of intracellular movement based on continuous actin assembly at one pole of the bacterium. this process requires the asymmetrical expression of the acta surface protein in l. monocytogenes and the icsa (virg) surface protein in s. flexneri. acta and icsa share no sequence homology. to assess the role of the two proteins in the generation of act ... | 1995 | 8748026 |
| salmonella typhimurium secreted invasion determinants are homologous to shigella ipa proteins. | salmonella typhimurium secreted proteins (ssp) were previously implicated in epithelial cell invasion. here we describe four genes (sspb, sspc, sspd, and sspa), located between spat and prgh, which encode proteins of 63, 42, 36, and 87 kda, respectively. these ssp are homologous to shigella flexneri secreted proteins ipab, ipac, ipad and ipaa. a non-invasive mutant with a transposon insertion in sspc lacks ssp of 87, 42 and 36 kda. complementation and analyses show that sspc and sspd encode the ... | 1995 | 8748032 |
| identification and characterization of phon-sf, a gene on the large plasmid of shigella flexneri 2a encoding a nonspecific phosphatase. | a gene encoding a nonspecific phosphatase, named phon-sf, was identified on the large virulence plasmid (pmysh6000) of shigella flexneri 2a ysh6000. the phosphatase activity in ysh6000 was observed under high-phosphate conditions. however, it was found that low-phosphate conditions induced a slightly higher level of activity. the nucleotide sequence of the phon-sf region cloned from pmysh6000 possessing the phon-sf gene encoded 249 amino acids with a typical signal sequence at the n terminus. th ... | 1996 | 8755883 |
| resection and mutagenesis of the acid ph-inducible p2 promoter of the agrobacterium tumefaciens virg gene. | transcription of the virg gene initiates from two tandem promoters, designated p1 and p2, that are located 50 nucleotides apart. transcription of the p2 promoter is induced by extracellular acidity. cis-acting sites required for p2 activity were identified by constructing and assaying a series of 5' and 3' resections and site-directed nucleotide substitutions. nucleotides between positions -9 and -37 were sufficient for regulated promoter activity. within this region, nucleotide substitutions at ... | 1996 | 8755905 |
| engineered deltaguab-a deltavirg shigella flexneri 2a strain cvd 1205: construction, safety, immunogenicity, and potential efficacy as a mucosal vaccine. | shigella flexneri 2a strain cvd 1204, which was constructed by introducing a specific, in-frame deletion mutation in the guab-a operon, was compared with deltaaroa strain cvd 1201. cvd 1204 was less invasive for hela cells than cvd 1201, whereas following invasion, the abilities of the two mutants to proliferate intracellularly were similarly impaired. the reduction in invasiveness was independent of the guanine auxotrophic phenotype and fully recovered when the chromosomal deletion mutation in ... | 1996 | 8757833 |
| microbiology of hiv associated bacteraemia and diarrhoea in adults from nairobi, kenya. | we undertook a retrospective descriptive comparison of the spectrum of pathogens responsible for bacteraemia and diarrhoea in hiv antibody positive and negative patients over 4 years (1988-92), in nairobi, kenya. the study population was recruited from primary to tertiary centres of clinical care and consisted of 2858 adults (15 years or older). there were 415 significant blood culture isolates, 192 from 1785 hiv negative patients and 223 from 953 hiv positive patients. there were 233 significan ... | 1996 | 8760961 |
| genetic polymorphism of the ipah multicopy antigen gene in shigella spps. and enteroinvasive escherichia coli. | the ipah loci comprise a multicopy antigen gene family unique to shigella species and enteroinvasive escherichia coli (eiec). dna probes derived from the shigella flexneri serotype 5 ipah7.8 gene were used to compare the molecular arrangement of ipah alleles in a variety of shigella and eiec strains. multiple copies of ipah-homologous sequences were detected in all invasion plasmids examined. oligonucleotide probes covering discrete 24 bp segments of the ipah7.8 gene and sequences flanking the i ... | 1995 | 8778567 |
| immunomagnetic separation and pcr detection show shigellae to be common faecal agents in children from urban marginal communities of costa rica. | culture and immunomagnetic separation-polymerase chain reaction assays (ims-pcr) were used to isolate and identify shigella flexneri, s. dysenteriae type i and s. sonnei in faeces from 250 children up to 5 years and from their mothers (n = 143) selected at random from a large urban marginal community of costa rica. children hospitalized because of severe diarrhoea (n = 110) were also studied. only s. flexneri, mainly serotype 2a, and s. sonnei were found by culture. all specimens in which shigel ... | 1996 | 8793710 |
| bacterial entry into epithelial cells: the paradigm of shigella. | shigella flexneri is a model for the entry of bacterial pathogens into nonphagocytic epithelial cells. on contact with the epithelial cell surface, the ipa proteins are secreted from the bacterium. the ipa complex then triggers a reorganization of the host-cell cytoskeleton leading to the formation of membrane ruffles, which engulf the bacterium. | 1996 | 8795157 |
| detection of antibodies to shigella lipopolysaccharide in urine after natural shigella infection or vaccination. | the purpose of the present study was to explore the possibility of detecting antibodies to shigella sonnei lipopolysaccharide (lps) in urine after infection or vaccination. urinary immunoglobulin a (iga) and igg antibodies and specific iga secretory protein against s. sonnei lps were measured by enzyme-linked immunosorbent assay (elisa), after adjustment for urine concentration. a significant antibody level was defined as one above a cutoff value calculated from the geometric mean + 2 standard d ... | 1996 | 8807212 |
| effect of saccharomyces boulardii against experimental oral infection with salmonella typhimurium and shigella flexneri in conventional and gnotobiotic mice. | saccharomyces boulardii was shown to be capable of inhibiting multiplication of enteropathogenic bacteria in vitro and is currently used for its anti-diarrhoea properties. we studied the capacity of this yeast to antagonize salmonella typhimurium and shigella flexneri in the intestinal tract of conventional or gnotobiotic nmri mice. conventional animals were given daily 10 mg doses of s. boulardii, whereas germ-free animals were given a single 10 mg dose. both groups were challenged orally 5 d l ... | 1996 | 8810053 |
| failure of cefotaxime therapy in a child with shigellosis. | | 1996 | 8822296 |
| identification and characterization of ispa, a shigella flexneri chromosomal gene essential for normal in vivo cell division and intracellular spreading. | the virulent phenotype of shigella requires loci on the chromosome as well as on the large virulence plasmid, and is regulated via a complex web of interactions amongst various chromosomal and large plasmid genes. to further investigate the role of chromosomal loci in virulence, we performed random tn10 mutagenesis in shigella flexneri ysh6000t, and isolated an avirulent mutant (v3404) incapable of spreading throughout an epithelial cell monolayer. although v3404 initially spread intercellularly ... | 1996 | 8830250 |
| use of a conformationally restricted secondary structural element to display peptide libraries: a two-stranded alpha-helical coiled-coil stabilized by lactam bridges. | a model for an alpha-helical peptide library based on a lactam bridged stabilized two-stranded alpha-helical coiled-coil is described. sites for library display were incorporated in the middle of the peptide sequence of the most solvent accessible sites of a coiled-coil. a comparison was made between this coiled coil and a native coiled-coil based on the same sequence but lacking the lactam bridges. a lactam bridged peptide where the hydrophobic repeat consisted of all alanine residues, such tha ... | 1996 | 8831793 |
| prevalence of shigellosis in the u.s.: consistency with dose-response information. | every year there are estimated 300000 cases of shigella in the united states (bennett et al., 1987, am. j. prev. med. 3, 102-114). a beta-poisson model was fit to human dose-response information on pathogenic shigella using the maximum likelihood estimation technique (haas, 1983, am. j. epidemiol. 118, 573-582). pooled and separate data sets for the shigella species were fit to the beta-poisson model and 95% confidence limits and regions were calculated. shigella dysentariae and shigella flexner ... | 1996 | 8856376 |
| association of self-limited cytomegalovirus colitis and shigellosis in an immunocompetent patient. | cytomegalovirus (cmv) infection of the colon has been rarely reported in immunocompetent patients. patients with severe acute illness or disseminated cmv infection have high mortality. in contrast, the patients with local injury of the colon due either to other gastrointestinal infections or to anal intercourse, who are otherwise healthy, usually have self-limited disease. the cmv infection is believed to be the bystander and may be treated conservatively. concomitant cmv colitis and other gastr ... | 1996 | 8864682 |
| evolutionary perspective on a composite shigella flexneri 2a virulence plasmid-borne locus comprising three distinct genetic elements. | nucleotide sequence analysis of a shigella flexneri 2a virulence plasmid-borne locus revealed that it comprised three distinct genetic elements: a stretch of colicin 1a/1b-linked sequence, a truncated is911 element, and a third element containing two orfs that shared a high level of similarity to a salmonella-specific chromosomal sequence. examination of other known is911-like sequences showed that these sequences also were frequently associated with other accessory elements and appeared to be p ... | 1996 | 8870246 |
| a study of the optimum bacteriostatic action of a synthetic medicine on bacteria using a microcalorimetric method. | the growth thermograms of strain 6, 2b, 3b, 5b, 1a, x, and y of shigella flexneri with the inhibitory action of a synthetic medicine were determined by using the 2277 thermal activity monitor. using a microorganism growth model with inhibitory conditions, the specific growth rate (mu) at different concentrations (c) of a synthetic medicine were calculated and the mu approximately c equations were established. from these mu approximately c equations, the concentration of the synthetic medicine wi ... | 1996 | 8877116 |
| specificity of monoclonal antibodies elicited by mucosal infection of balb/c mice with virulent shigella flexneri 2a. | protective immunity against shigellosis is thought to be determined by the o-antigen side chains of the lipopolysaccharide (lps) molecule. to study possible common protective epitopes, monoclonal antibodies reacting with shigella flexneri 2a lps were generated from balb/c mice infected ocularly with the virulent serotype 2a strain s. flexneri 2457t and tested against a panel of s. flexneri lpss by enzyme-linked immunosorbent and immunoblot assays. four monoclonal antibodies were identified, all ... | 1996 | 8877140 |
| construction and characterization of virg (icsa)-deleted escherichia coli k12-shigella flexneri hybrid vaccine strains. | human challenge studies with ecsf2a-2, an arod deletion-attenuated escherichia coli k12-shigella flexneri hybrid vaccine expressing s. flexneri 2a somatic antigen and the invasive phenotype indicated that, at doses of 2 x 10(9) bacteria, ecsf2a-2 was immunogenic but also reactogenic and therefore not sufficiently attenuated. two factors that may contribute to the residual reactogenicity are the spontaneous appearance of plaque-positive variants in the e. coli k12 recipient and the presence of th ... | 1996 | 8879102 |
| cross-reactivity of shigella flexneri serotype 2a o antigen antibodies following immunization or infection. | to study the cross-reactivity pattern of shigella flexneri 2a o-antigen antibodies, sera from humans and monkeys challenged with s. flexneri 2a, and from humans and guinea pigs immunized with a recombinant vaccine expressing serotype 2a o-antigen, were tested against a panel of lipopolysaccharide extracted from heterologous s. flexneri. sera from the two groups of humans, who were volunteers in either a clinical challenge or vaccination study, showed similar patterns: cross-reactivity was more o ... | 1996 | 8879103 |
| treatment of hela cells with bacterial water extracts inhibits shigella flexneri invasion. | pathogenesis mediated by shigella flexneri requires invasion of the gastrointestinal epithelium. it has been previously shown that hela cells challenged with s. flexneri show alterations in their phosphotyrosine-containing protein profile. in this report, we demonstrated that bacterial water extracts (we) abrogated the invasion of hela cells by s. flexneri in a dose-dependent manner. a proteinaceous component of s. flexneri was shown to be responsible for this inhibitory activity. proteins encod ... | 1996 | 8880141 |
| growth of shigella flexneri in foods: comparison of observed and predicted growth kinetics parameters. | shigella causes foodborne gastrointestinal illness; however, little information is available on its ability to grow in foods. commercially available sterile foods (uht milk, beef broth, chicken broth, vegetable broth, meats, vegetables) were inoculated with s. flexneri 5348 and incubated at 12, 15, 19, 28 or 37 degrees c. growth curves were fitted from plate count data by the gompertz equation and exponential growth rates, generation times, lag times and maximum population densities were derived ... | 1996 | 8880330 |
| evaluation of an extended blood culture protocol to isolate fastidious organisms from patients with aids. | recent reports of fastidious pathogens suggest the need for special blood cultures for immunocompromised patients. blood cultures from 45 human immunodeficiency virus (hiv)-infected patients with unexplained fever (> or = 38.0 degrees c) and cd4 counts of < 125 cells per mm3 were collected into a vacuum tube with sodium polyanetholsulfonate, an isolator tube, and bactec aerobic and anaerobic bottles. blood from the sodium polyanethosulfonate tube was inoculated into bactec 13a bottles, which wer ... | 1996 | 8880497 |
| identification of sigma s-dependent genes associated with the stationary-phase acid-resistance phenotype of shigella flexneri. | shigella flexneri grown to stationary phase has the ability to survive for several hours at ph 2.5. this acid resistance, which may contribute to the low infective dose associated with shigellosis, is dependent upon the expression of the stationary-phase-specific sigma factor sigma s. using random tnphoa and tnlacz mutagenesis we isolated five acid-sensitive mutants of s. flexneri, which had lost their ability to survive at ph 2.5 for 2 h in vitro. each transposon insertion with flanking s. flex ... | 1996 | 8885264 |
| salmonella spp. are cytotoxic for cultured macrophages. | we have shown by a variety of microscopical and biochemical techniques that salmonella spp. are cytotoxic for cultured j774a.1 and bone marrow-derived murine macrophages. the cytotoxicity is initially manifested by inhibition of membrane ruffling and macropinocytosis in infected macrophages, and is followed by cell death. macrophages killed by salmonella spp. exhibited features of apoptosis such as condensation and fragmentation of chromatin, membrane blebbing, and the presence of cytoplasmic nu ... | 1996 | 8885278 |
| risk factors for deaths in under-age-five children attending a diarrhoea treatment centre. | few case-control studies have examined possible risk factors for diarrhoeal deaths in under-age-five children in the developing countries. we analysed data from the surveillance system of our diarrhoea treatment centre/hospital for the period 1990-94 on 928 children less than 5 years of age. in univariate analysis, 11 factors were significantly associated with death: lack of breastfeeding, severe malnutrition, complicated diarrhoea, pneumonia, xerophthalmia, duration of diarrhoea 7-14 days, mode ... | 1996 | 8888920 |
| safety, immunogenicity, and transmissibility in humans of cvd 1203, a live oral shigella flexneri 2a vaccine candidate attenuated by deletions in aroa and virg. | we evaluated the safety and immunogenicity of attenuated shigella flexneri 2a vaccine candidate cvd 1203, which harbors precise deletions in the plasmid gene virg and in the chromosomal gene aroa. cvd 1203 invades epithelial cells but undergoes minimal intracellular proliferation and cell-to-cell spread. fasting healthy volunteers, aged 18 to 40 years, were randomly allocated (double-blind design) to receive either cvd 1203 vaccine or placebo, along with sodium bicarbonate buffer, on days 0 and ... | 1996 | 8890204 |
| enteropathogens associated with childhood diarrhea in italy. the italian study group on gastrointestinal infections. | infectious diarrheal diseases remain an important cause of childhood morbidity in industrialized countries. the knowledge of the etiology and epidemiology of childhood diarrhea in a given area is needed to plan any measure designed to prevent or ameliorate diarrheal illness and to develop practice guidelines for the most appropriate stool examination procedures. | 1996 | 8895919 |
| processing of the aida-i precursor: removal of aidac and evidence for the outer membrane anchoring as a beta-barrel structure. | the aida-i adhesin known to be responsible for the diffuse adherence (da) phenotype of the diarrhoeagenic escherichia coli (daec) strain 2787 has been shown previously to be synthesized as a precursor protein and to undergo additional c-terminal processing. here, the c-terminal processing of the aida-i precursor and the outer membrane topology of the cleaved c-terminal fragment, aidac, were investigated. by isolation of the cleaved aidac fragment and n-terminal sequencing, the c-terminal cleavag ... | 1996 | 8899706 |
| effect of o side-chain length and composition on the virulence of shigella flexneri 2a. | icsa of shigella flexneri is required for intercellular spread and is located in the outer membrane at one pole of the bacterium, where it catalyses the polymerization of host-cell actin. the formation of the a tin tail provides the force to move the bacterium in a unidirectional manner through the host-cell cytoplasm. we have previously demonstrated that rough lipopolysaccharide (lps) mutants of s. flexneri 2a are avirulent and cannot form plaques in tissue-culture monolayers. this inability to ... | 1996 | 8899709 |
| shigellosis in children: clinical and laboratory features. | | 1995 | 8904140 |
| towards a vaccine candidate against shigella dysenteriae 1: expression of the shiga toxin b-subunit in an attenuated shigella flexneri arod carrier strain. | shiga toxin is considered to be one of the main causes of severe side effects, such as the hemolytic uremic syndrome, of shigellosis. the genetic determinants for a fusion of its b-subunit (stxb), which mediates toxin binding to target cells, with the cooh-terminus of escherichia coli hemolysin a (stx'-'hlya) has been combined with the determinants of the accessory translocator proteins hlyb and hlyd in a notl cassette. this cassette has been integrated via a mini-transposon into a recombinant v ... | 1996 | 8905616 |
| the nadb gene of salmonella typhimurium complements the nicotinic acid auxotrophy of shigella flexneri. | shigella species are characteristically nicotinic acid (na) auxotrophs. the invasive s. flexneri strain m90t, transformed with the multicopy plasmid pzt349 encoding the nadb gene of salmonella typhimurium, can grow in minimal glucose medium without exogenous na, whereas, m90t containing the control vector, puc18 does not, suggesting that this species lacks l-aspartic acid oxidase, the first enzyme in the de novo nad biosynthetic pathway. the estimated growth rate of strain m90t (pzt349) in hela ... | 1996 | 8914524 |
| lipopolysaccharide-specific antibodies in plasma and stools of children with shigella-associated leukemoid reaction and hemolytic-uremic syndrome. | antibody responses to the lipopolysaccharide (lps) of shigellae were compared between children with uncomplicated and complicated shigella dysenteriae 1 infection. one hundred fifteen children between 12 and 60 months of age with s. dysenteriae 1 infection were studied. of these children, 42 had complications (leukemoid reaction and/or hemolytic-uremic syndrome [complicated shigellosis] and 73 had no complications (uncomplicated shigellosis). antibodies to the lps of s. dysenteriae 1 and shigell ... | 1996 | 8914761 |
| a shigella flexneri invasion plasmid gene, ipgh, with homology to is629 and sequences encoding bacterial sugar phosphate transport proteins. | sequences representing the 2684 bp flanking the ipah4.5 gene on the invasion plasmid of shigella flexneri 5 indicate an unusual fusion gene, designated ipgh, in which the first 27 amino acids (aa) are identical to orf2 of is629. the aa sequence encoded by the remainder of ipgh bears significant homology to escherichia coli and to salmonella typhimurium glpt and uhpt proteins and to the s. typhimurium pgtp protein, which are involved in the uptake of high-energy sugar phosphates from an external ... | 1996 | 8917071 |
| shigella isolates in stool. | a total of 447 shigella strains were isolated from stool samples during 1989-1991. of these 270 (60%) were from children. among the different species and serotypes sh. flexneri 60 (13.4%) and sh. sonnei phage 139 (65%) were the most frequently isolated strains. 154 (34.4%) strains were resistant to three and 179 (40%) to more than three antibiotics. some strains of shigella were found to be resistant to furazolidine and neomycin. | 1995 | 8919104 |
| semiquantitative estimation of shigella antigen-specific antibodies: correlation with disease severity during shigellosis. | systemic and mucosal antibody responses during shigellosis were analysed and correlated with clinical severity. patients infected with shigella dysenteriae type 1 (sdip), and s. flexneri (sfip) were grouped according to disease severity. the disease was more severe in sdip than in sfip. higher levels of shigella antigen-specific serum antibodies were associated with severe disease. in contrast, decreased serum levels of igg, igm and total protein were associated with severe disease. faecal level ... | 1996 | 8920810 |
| safety and immunogenicity of investigational shigella conjugate vaccines in israeli volunteers. | the safety and immunogenicity of investigational conjugates, composed of the o-specific polysaccharides of shigella sonnei and shigella flexneri type 2a covalently bound to pseudomonas aeruginosa recombinant exoprotein a (repa), were evaluated in 192 israeli soldiers. none had significant local reactions or fever. fourteen days after injection, 90% of s. sonnei-repa recipients and 73 to 77% of s. flexneri-repa recipients had a fourfold or greater increase in serum immunoglobulin g (igg) and iga ... | 1996 | 8926071 |
| soluble invasion plasmid antigen c (ipac) from shigella flexneri elicits epithelial cell responses related to pathogen invasion. | shigella flexneri invades colonic epithelial cells by pathogen-induced phagocytosis. the three proposed effectors of s. flexneri internalization are invasion plasmid antigens b (ipab), ipac, and ipad, which are encoded on the pathogen's 230-kb virulence plasmid and translocated to the extracellular milieu via the mxi-spa translocon. to date, there are no definitive functional data for any purified ipa protein. here, we describe the first characterization of highly purified recombinant ipac, whic ... | 1996 | 8926086 |
| characterization of espc, a 110-kilodalton protein secreted by enteropathogenic escherichia coli which is homologous to members of the immunoglobulin a protease-like family of secreted proteins. | enteropathogenic escherichia coli (epec) secretes at least five proteins. two of these proteins, espa and espb (previously called eaeb), activate signal transduction pathways in host epithelial cells. while the role of the other three proteins (39, 40, and 110 kda) remains undetermined, secretion of all five proteins is under the control of pera, a known positive regulator of several epec virulence factors. on the basis of amino-terminal protein sequence data, we cloned and sequenced the gene wh ... | 1996 | 8932311 |
| in vivo apoptosis in shigella flexneri infections. | shigella flexneri, an etiological agent of bacillary dysentery, causes apoptosis in vitro. here we show that it also induces apoptosis in vivo. we were able to quantify the number of apoptotic cells in rabbit peyer's patches infected with s. flexneri by detecting cells with fragmented dna. infection with virulent s. flexneri results in massive numbers of apoptotic cells within the lymphoid follicles. in contrast, neither an avirulent strain nor an avirulent strain capable of colonizing peyer's p ... | 1996 | 8945588 |
| [expression of s.sonnei form i antigen gene and v.cholerae toxin b subunit gene in s.flexneri 2a strain and investigation of their immunoprotective response in mice]. | the genes encoding s. sonnei form i o antigen and v. cholerae b subunit were cloned into an expression vector containing asd gene of streptococcus mutans by gene recombination. the final recombination plasmid was transformed into the asd mutant of s. flexneri 2a (strain t32). analysis of lps silver staining and western blotting indicated that the genes encoding ct-b and form i o antigen could stably express in the asd mutant t32 strain. immune protection tests in mice showed that the recombinant ... | 1996 | 8950856 |