Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| congo red-mediated regulation of levels of shigella flexneri 2a membrane proteins. | the ability of shigella spp. to bind congo red from agar medium is generally correlated with their virulence properties. we used a metabolically active culture of shigella flexneri 2a to determine the effect of congo red on its membrane protein profiles. virulent s. flexneri grown in the presence of congo red at 37 degrees c showed increased levels of three proteins with mrs of 43,000, 58,000, and 63,000 (43k, 58k, and 63k proteins) in the sarkosyl-soluble membrane fractions. the observed phenom ... | 1989 | 2663721 |
| [the role of delayed hypersensitivity in the development of an experimental dysentery infection and vaccinal process]. | the results of experiments, indicating the development of cell-mediated delayed hypersensitivity (dh) skin reaction, its dependence on the virulence of shigella flexneri 2a, the dose and the character of the antigen used for testing the reaction, are presented. one of the immunologically active components of s. flexneri virulent strain 2a no. 516 is a biologically active thermolabile factor detected in filtrate and supernatant fluid. these data suggest that the immunosuppressive action of the vi ... | 1989 | 2698032 |
| potential shigella flexneri 2a and shigella sonnei i live vaccinal strains. characterization of immunogenicity in animal models. | rats and rabbits were immunized intraintestinally with different doses of virulent and nonvirulent live shigella flexneri 2a and shigella sonnei i strains. the nonvirulent strains had one or two attenuating markers. the period of excretion with the faeces of the bacteria and of their polysaccharide antigens, the proliferation of antigen-binding and antibody-producing cells in the spleens and gut-associated lymphoid tissues and the levels of antibodies in sera and faeces were studied. attenuated ... | 1990 | 2099082 |
| live shigella flexneri 2a and shigella sonnei i vaccine candidate strains with two attenuating markers. i. construction of vaccine candidate strains with retained invasiveness but reduced intracellular multiplication. | live shigella flexneri 2a and shigella sonnei phase i vaccine candidate strains with two virulence-reducing markers were constructed through stepwise incorporation of weakly attenuating purine auxotrophy with subsequent rifampicin-resistance (rna polymerase) mutation to yield optimal attenuation. these vaccine candidate strains showed an unaltered plasmid profile; did not cause keratoconjunctivitis in the sereny test, while being excreted for a short but still marked period and providing partial ... | 1990 | 2180230 |
| live shigella flexneri 2a and shigella sonnei i vaccine candidate strains with two attenuating markers. ii. preliminary results of vaccination of adult volunteers and children aged 2-17 years. | shigella flexneri 2a and shigella sonnei i vaccine candidate strains were tested for tolerance in 14 adults as well as for tolerance and immunogenicity in children aged 2-17 years. for fresh culture material, the limit for side effects fading within 36 h such as meteorism, loose stools, tenesmus and slight temperature, and tolerated by volunteers was 3 x 10(9) colony-forming units (c.f.u.). excretion of vaccine strain germs for 2-3 days was observed only at doses of 10(10) c.f.u. and greater (2- ... | 1990 | 2180231 |
| molecular epidemiology of shigella infection in central australia. | shigellosis is endemic in central australia and the infections are predominantly due to shigella flexneri 6, shigella flexneri 2a and shigella sonnei. plasmid profiles of isolates collected from 1985-9, suggested that infections caused by shigella flexneri 6 were predominantly due to a single clone, whereas those caused by shigella flexneri 2a and shigella sonnei were due to several genetically diverse strains, although strains with identical plasmid profiles were found in widely separated geogr ... | 1990 | 2200701 |
| [cloning of shigella flexneri 2a genes coding for restriction- modification system sfl2ai]. | the sfl2ai system of restriction-modification (rm) was revealed in the cells of shigella flexneri encoded by pkmr114 plasmid belonging to the incn incompatibility group. the genes for sfl2ai rm system were cloned. the system was ascribed to the enzymes of the ecorii specificity, as shown by in vivo and in vitro experiments. restriction analysis of these genes' region and antigenic properties of the sfl2ai endonuclease pointed to significant differences between this and ecorii rm systems. | 1990 | 2227395 |
| sensitivity of shigella flexneri and escherichia coli bacteria to bacteriophages and to colicins, lost or established by the acquisition of r plasmids. | lac+ recombinant of shigella flexneri 2a carrying r-factors of the standard set have been constructed. the r+ transconjugants obtained have been compared with the original strain with respect to their susceptibility to a set of bacteriophages recommended for phagetyping of shigella strains and to a set of colicins. it have been found that as a result of acquiring some r-factors the susceptibility to bacteriophages changes; presence of certain r-factors causes susceptibility, that of other r-fact ... | 1990 | 1715637 |
| technological aspect of the production of live dysentery vaccines for oral administration. | an experimental technology for the production of live freeze-dried vaccines prepared from attenuated shigella flexneri 2a and shigella sonnei i strains was developed. it is based on the cultivation of bacterial strains in a fermentor under conditions which ensure high yields. the strains grow in s-form, their antigenic structure is preserved and they remain non-virulent. the attenuating markers are stable. the freeze-dried vaccines retain good immunogenicity when applied intra-intestinally to ra ... | 1991 | 1805499 |
| effect of prior infection with virulent shigella flexneri 2a on the resistance of monkeys to subsequent infection with shigella sonnei. | all virulent shigellae have large plasmids. plasmid-associated genes encode the expression of membrane-associated proteins (map), some of which correlate with the ability to invade susceptible epithelial cells. these map are serologically related in all of the shigella serotypes and evoke an antibody response after infection. to determine whether the map have a significant role in protection, 24 monkeys were infected with virulent shigella flexneri 2a. after recovery, one group (with controls) w ... | 1991 | 1869840 |
| virulence phenotype and genetic characteristics of the t32-istrati shigella flexneri 2a vaccine strain. | the t32-istrati strain, which has been used as an oral attenuated shigella flexneri 2a vaccine, has lost the invasive phenotype due to a spontaneous deletion in the shigella virulence plasmid. this deletion has eliminated three plasmid loci (ipabcda, inva and virg) that are necessary for production of a positive sereny test by shigella species. virulence in the sereny test was reconstituted in the t32-istrati strain by the conjugal transfer of an intact 140 m da virulence plasmid from s. flexner ... | 1991 | 1872021 |
| [an immunomorphological study of the lymphoid organs in the experimental administration of virulent and avirulent shigella flexneri 2a strains]. | 1991 | 1887717 | |
| epidemiologic patterns of acute diarrhea and endemic shigella infections in children in a poor periurban setting in santiago, chile. | to prepare a field site for evaluating preventive interventions against endemic shigellosis, the authors followed prospectively a cohort of 360 children (90 each of children aged 0-11, 12-23, 24-35, and 36-47 months) in santa julia, a low socioeconomic area in santiago, chile, from november 1986 through april 1989 with twice weekly household visits for diarrheal disease; infants replaced children who reached 60 months of age. coprocultures on 2 consecutive days from children with diarrhea and fr ... | 1991 | 1951266 |
| differences in blood group b-specific mucinase activity between virulent and avirulent shigella flexneri 2a strains. | based on our previous findings we postulate that the production of blood group b-degrading mucinase by shigella flexneri 2a is related to virulence. the virulent s. flexneri 2a strain m4243 produced a blood group b mucinase which decreased the blood group b reactivity of germ-free mouse mucins by a factor of 16 and the b reactivity of human saliva by a factor of 32. avirulent s. flexneri 2a b-1, serologically similar, but not genetically identical to the m4243 strain, failed to degrade the blood ... | 1991 | 1961109 |
| construction of aromatic dependent shigella flexneri 2a live vaccine candidate strains: deletion mutations in the aroa and the arod genes. | live shigella flexneri 2a vaccine candidate strains with deletion mutations in the aro genes were constructed. tn10-generated auxotrophic mutations were transduced from escherichia coli to s. flexneri 2a with bacteriophage p1cmcts. the tetracycline-sensitive derivatives of tn10 mutants obtained were selected on bochner's medium and checked by dna-dna hybridization using aroa and arod gene specific probes. the vaccine candidate strains were tested to assess the efficacy of protection in guinea-pi ... | 1991 | 2008803 |
| two novel virulence loci, mxia and mxib, in shigella flexneri 2a facilitate excretion of invasion plasmid antigens. | a bank of over 4,200 lacz protein fusions in shigella flexneri 2a was screened for fusions to temperature-regulated promoters. one mutant, bs260, was completely noninvasive on hela cells and mapped to a region on the 220-kb virulence plasmid in which we had previously localized several avirulent temperature-regulated operon fusions (a.e. hromockyj and a.t. maurelli, infect. immun. 57:2963-2970, 1989). the phenotype of bs260 was similar to that of the previously identified mxi (membrane expressio ... | 1991 | 2037361 |
| construction of a physical map of the chromosome of shigella flexneri 2a and the direct assignment of nine virulence-associated loci identified by tn5 insertions. | to establish the molecular basis of the chromosomal virulence genes of shigella flexneri 2a (ysh6000), a notl restriction map of the chromosome was constructed by exploiting notl-linking clones, partial notl digestion and dna probes from various genes of escherichia coli k-12. the map revealed at least three local differences in the placements of genes between ysh6000 and e. coli k-12. using the additional notl sites introduced by tn5 insertion, nine virulence loci identified previously by rando ... | 1991 | 1662762 |
| an o antigen can interfere with the function of the yersinia pseudotuberculosis invasin protein. | escherichia coli strains harbouring the yersinia pseudotuberculosis inv gene are able to enter cultured mammalial cells. we show here that this property is not shared by all enteric bacteria, since shigella flexneri 2a cured of its virulence-associated plasmid and harbouring the inv gene is unable to enter mammalian cells efficiently. mapping studies showed that the region of the chromosome responsible for this phenotype includes rfab, a locus involved in the production of o antigen. s. flexneri ... | 1991 | 1710312 |
| spontaneous insertion of an is1-like element into the virf gene is responsible for avirulence in opaque colonial variants of shigella flexneri 2a. | colonial variation of shigella flexneri serotype 2a from the translucent (2457t) to the opaque form (2457o) occurs spontaneously once in 10(4) cell divisions, with concomitant loss of ipa gene expression and virulence. the appearance of 2457o was associated with the insertional inactivation of virf, an invasion plasmid-encoded positive regulator of ipa gene expression. plasmid pwr110, a tn5-tagged invasion plasmid that restores the invasive phenotype to plasmid-cured shigella derivatives, was co ... | 1992 | 1309511 |
| vacb, a novel chromosomal gene required for expression of virulence genes on the large plasmid of shigella flexneri. | shigellae, the causative agents of bacillary dysentery, are capable of adhering to and invading epithelial cells and spreading into adjacent cells. a chromosomal mutant of shigella flexneri 2a ysh6000 with reduced invasive capacity was isolated by tn5 insertion mutagenesis. the linkage of the mutant phenotype to the tn5 insertion was determined by p1 phage transduction. the site of the tn5 insertion was assigned to a noti chromosomal restriction map, confirming that the virulence-associated locu ... | 1992 | 1400189 |
| identification and characterization of virk, a virulence-associated large plasmid gene essential for intercellular spreading of shigella flexneri. | seven virulence loci have been identified by tn5 insertion mutagenesis on the large 230 kb plasmid (pmysh6000) of shigella flexneri 2a. in this study, we used tn10 insertion mutagenesis and identified a novel virulence locus on pmysh6000 responsible for bacterial spread. characterization of the invading bacteria of the tn10 insertion mutants in the epithelial cells revealed that the bacteria were capable of at least some intracellular spreading but not intercellular spreading. immunoblot analysi ... | 1992 | 1406277 |
| presence of specific immunoglobulin a-secreting cells in peripheral blood after natural infection with shigella sonnei. | the appearance of antigen-specific immunoglobulin a (iga) antibody-secreting cells (ascs) following natural infection with shigella sonnei during a common-source outbreak caused by this organism was evaluated in a modified enzyme-linked immunosorbent assay (elispot). a mean iga asc value of 2,131.6/10(6) cells against homologous s. sonnei lipopolysaccharide (lps) was detected in blood samples obtained from patients with bacteriologically proven s. sonnei shigellosis 5 and 10 days after the onset ... | 1992 | 1500527 |
| safety, immunogenicity, and efficacy in monkeys and humans of invasive escherichia coli k-12 hybrid vaccine candidates expressing shigella flexneri 2a somatic antigen. | a live, oral shigella vaccine, constructed by transfer of the 140-mda invasiveness plasmid from shigella flexneri 5 and the chromosomal genes encoding the group- and type-specific o antigen of s. flexneri 2a to escherichia coli k-12, was tested in humans. designated ecsf2a-1, this vaccine produced adverse reactions (fever, diarrhea, or dysentery) in 4 (31%) of 13 subjects who ingested a single dose of 1.0 x 10(9) cfu, while at better-tolerated doses (5.0 x 10(6) to 5.0 x 10(7) cfu), it provided ... | 1992 | 1587589 |
| age-specific prevalence of serum antibodies to the invasion plasmid and lipopolysaccharide antigens of shigella species in chilean and north american populations. | shigella species have virulence plasmids that encode outer membrane proteins (invasion plasmid antigens, ipa) associated with pathogenicity. western blots were used to detect antibodies to ipa in sera from 390 chilean children, and these responses were compared with those of a us population of infants and adults. antibodies to lipopolysaccharide (lps) of plesiomonas shigelloides and shigella flexneri 2a were measured by elisa. among the chileans, there was an age-related acquisition of ipa antib ... | 1992 | 1607690 |
| virulence phenotypes of shigella flexneri 2a avirulent mutant 24570 can be complemented by the plasmid-coded positive regulator virf gene. | avirulent mutation of an opaque colony variant of shigella flexneri 2a designated 24570 has been believed to be linked with the glpk locus of the chromosome. however, avirulent phenotypes of the 24570 strain could be complemented by the invasion plasmid-coded virf gene, a positive regulator for invasion genes. the 24570 strain had a dna structural alteration upstream of the virf gene. | 1992 | 1624118 |
| antibodies to shiga holotoxin and to two synthetic peptides of the b subunit in sera of patients with shigella dysenteriae 1 dysentery. | acute- and convalescent-phase sera from 18 thai patients and convalescent-phase sera from two israeli patients and one bangladeshi patient with shigella dysenteriae 1 (shiga) dysentery were tested by enzyme-linked immunosorbent assay to detect antibodies that bind s. dysenteriae lipopolysaccharide (lps), shiga holotoxin, or two synthetic peptides representing epitopes from the b subunit of shiga toxin. paired sera from 24 maryland adults with shigella flexneri 2a or shigella sonnei diarrhea serv ... | 1992 | 1629317 |
| mxia of shigella flexneri 2a, which facilitates export of invasion plasmid antigens, encodes a homolog of the low-calcium-response protein, lcrd, of yersinia pestis. | the plasmid-encoded invasion plasmid antigen (ipa) export accessory locus of shigella flexneri 2a, mxia, was cloned, and the complete dna sequence of the gene was determined. the mixa open reading frame was found to encode a polypeptide of 74.03 kda with a pi of 5.02. a hydropathy analysis of the predicted protein revealed a hydrophilic c terminus and an extremely hydrophobic n terminus without a cleavable signal sequence but with several potential membrane-spanning regions. while a homology sea ... | 1992 | 1639496 |
| morpho-physiologic characteristics of escherichia coli and shigella flexneri 2a carrying the htpr15 gene. | electron microscopic examination of the morphology of normal escherichia coli mc4100 and shigella flexneri cells and their htpr-defective recombinants has shown the presence in the latter of noncrystalline granules after growth at 37 degrees c. the defect of the htpr gene leads to some changes in ultrastructure of bacterial colonies and the intensification of the processes of development and aging of colonies as integral structures. these phenomena are manifested by early formation of intercellu ... | 1993 | 8336285 |
| arod deletion attenuates shigella flexneri strain 2457t and makes it a safe and efficacious oral vaccine in monkeys. | the aromatic-dependent live shigella flexneri 2a vaccine strain sfl1070, with a deleted arod gene, had a much reduced intracellular growth in hela cells compared with its parent strain s. flexneri 2457t. s. flexneri sfl1070 gave no adverse effects in eight macaca fascicularis monkeys orally vaccinated with four doses of 1 x 10(11) live bacteria within a 5-week period, whereas s. flexneri 2457t caused dysentery in all eight non-vaccinated monkeys. thus the aromatic dependency rendered s. flexneri ... | 1993 | 8356844 |
| eight genes in region 5 that form an operon are essential for invasion of epithelial cells by shigella flexneri 2a. | the 7-kb region 5 on the large 230-kb plasmid pmysh6000 in shigella flexneri 2a ysh6000 is one of the virulence-associated dna segments required for the invasion of epithelial cells (c. sasakawa, k. kamata, t. sakai, s. makino, m. yamada, n. okada, and m. yoshikawa, j. bacteriol. 170:2480-2484, 1988). to elucidate the functional organization of region 5 and to determine the virulence-associated genes encoded by region 5, we performed insertion and deletion mutagenesis, dna subcloning, and comple ... | 1993 | 8385666 |
| site of transcriptional activation of virb on the large plasmid of shigella flexneri 2a by virf, a member of the arac family of transcriptional activators. | virb plays a central role in the regulation of virulence of shigella flexneri. it acts as a transcriptional activator and is itself transcriptionally activated by another virulence protein, virf. experiments were performed in order to identify the site upstream of virb at which virf binds in order to activate transcription. progressive 5' deletions of the dna upstream of the transcription start point of virb were constructed by subcloning and bal31 deletion. these deletion derivatives were clone ... | 1993 | 8412620 |
| evaluation of shigella vaccine safety and efficacy in an intranasally challenged mouse model. | five shigella vaccine candidates (ecsf2a-1, ecsf2a-2, sfl124, t32-istrati and smd) were tested for safety and efficacy in balb/cj mice using an intranasal challenge model. experiments in this model suggest that (i) the relative attenuation of vaccines can be determined in mice by intranasal inoculation, (ii) all vaccines tested elicited antibacterial mucosal immunity protecting against pulmonary infection with shigella flexneri 2a, (iii) protection was associated with serum iga and/or igg antibo ... | 1993 | 8438617 |
| shigella flexneri 2a and sonnei i vaccine with two attenuating markers: construction, tolerability and immunogenicity in 143 children aged 3-17 years. | the vaccine candidates were constructed through stepwise incorporation of weakly attenuated purine auxotrophy with subsequent rifampicin resistance (rna polymerase) mutation to yield optimal attenuation. these strains showed a maintained invasiveness for conjunctival epithelia. therefore, while not causing keratoconjunctivitis, they were excreted for a short but marked period and provided partial protection in the sereny test. children tolerated the maximum dose of 1-3 x 10(9) colony-forming uni ... | 1993 | 8438618 |
| immunogenicity and efficacy of oral or intranasal shigella flexneri 2a and shigella sonnei proteosome-lipopolysaccharide vaccines in animal models. | immunity against shigellosis has been shown to correlate with the presence of antibodies specific for shigella lipopolysaccharide (lps). we here propose a new candidate vaccine for shigellosis composed of purified shigella flexneri 2a or shigella sonnei lps hydrophobically complexed with group c type 2b neisseria meningitidis outer membrane protein proteosomes. immunization of mice either orally or intranasally with this complex induced specific homologous anti-lps antibodies in both intestinal ... | 1993 | 8500877 |
| construction and characterization of attenuated delta aroa delta virg shigella flexneri 2a strain cvd 1203, a prototype live oral vaccine. | we engineered an oral shigella vaccine prototype that can invade intestinal epithelial cells but cannot undergo extensive intracellular replication or extend to adjacent epithelial cells. strain cvd 1203, derived from wild-type shigella flexneri 2a by introducing deletions in chromosomal aroa and invasion plasmid virg, was highly attenuated in the sereny test. two 10(9)-cfu orogastric doses (2 weeks apart) stimulated production of secretory immunoglobulin a antibodies to s. flexneri 2a and prote ... | 1994 | 7927802 |
| enhancement of anti-shigella lipopolysaccharide (lps) response by addition of the cholera toxin b subunit to oral and intranasal proteosome-shigella flexneri 2a lps vaccines. | addition of the cholera toxin b subunit to oral and intranasal proteosome-shigella flexneri 2a lipopolysaccharide vaccines improved their immunogenicities. enhancement of anti-o-shigella immunoglobulin a levels was most evident in lung lavages following oral immunization and in lung and intestinal fluids when suboptimal doses were used with either immunization route. | 1994 | 7927807 |
| effect of subinhibitory concentrations of antimicrobial agents on virulence factors of shigella flexneri 2a and escherichia coli o124. | the effect of subinhibitory concentrations of rifampicin, chloramphenicol, tetracycline and nalidixic acid on the interaction of shigella flexneri 2a and escherichia coli o124 with hela cells was examined. antimicrobial agents altered adhesion, penetration and intracellular multiplication of the bacteria, as well as re-infection of adjacent cells. chloramphenicol increased the virulence of the bacterial strains whereas nalidixic acid, tetracycline and rifampicin diminished it. | 1994 | 7932621 |
| from the centers for disease control and prevention. outbreak of shigella flexneri 2a infections on a cruise ship. | 1994 | 7933412 | |
| outpatient studies of the safety and immunogenicity of an auxotrophic escherichia coli k-12-shigella flexneri 2a hybrid vaccine candidate, ecsf2a-2. | a phase ii study was conducted in 244 volunteers at fort ord, ca, to determine the safety and immunogenicity of ecsf2a-2, a live, oral shigella vaccine constructed by transfer of genes from shigella flexneri to escherichia coli k-12. in this placebo-controlled study, four doses of vaccine ranging from 2.3 to 9.0 x 10(8) colony-forming units were given on days 0, 3, 14 and 17. vaccine shedding occurred from 1 to 3 days after each dose. the vaccine was well tolerated at every dose tested. signific ... | 1994 | 8036831 |
| outbreak of shigella flexneri 2a infections on a cruise ship. | 1994 | 8072477 | |
| immunogenicity of two types of shigella flexneri 2a o-specific polysaccharide-tetanus toxoid conjugates. | 1994 | 8080210 | |
| nucleotide sequence of the rhamnose biosynthetic operon of shigella flexneri 2a and role of lipopolysaccharide in virulence. | n1308, a chromosomal tn5 mutant of shigella flexneri 2a, was described previously as a lipopolysaccharide (lps) mutant with a short o side chain. n1308 formed foci, but not plaques, in llc-mk2 cell monolayers and was negative in the serény test. in this study, the wild-type locus inactivated in n1308 was cloned and further defined by means of complementation analysis. a 4.3-kb bsteii-xhoi fragment of s. flexneri 2a ysh6200 dna was sufficient to restore both normal lps and virulence phenotype to ... | 1994 | 8157605 |
| 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 |
| 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 |
| identification of a novel virulence gene, vira, on the large plasmid of shigella, involved in invasion and intercellular spreading. | a novel virulence gene (vira) was identified upstream of the virg gene on the large plasmid of shigella flexneri 2a ysh6000. characterization of vira mutants infecting mk2 epithelial cell monolayers revealed that their invasive capacity was decreased to less than one fifth of the wild-type level. nevertheless, the bacteria were capable of expressing and secreting ipab, ipac and ipad proteins. the vira mutants were also impaired in their ability to spread intercellularly, since the bacteria gave ... | 1995 | 7494473 |
| recognition of three epitopic regions on invasion plasmid antigen c by immune sera of rhesus monkeys infected with shigella flexneri 2a. | the invasive ability of shigella spp. is correlated with the expression of several plasmid-encoded proteins, including invasion plasmid antigen c (ipac). by characterizing the antigenic structure of ipac with monoclonal antibodies and convalescent-phase sera, it may be possible to determine the physical location of specific epitopes as well as the involvement of epitopes in a protective immune response or the host's susceptibility to disease. by using overlapping octameric synthetic peptides, wh ... | 1995 | 7558301 |
| development of an improved animal model of shigellosis in the adult rabbit by colonic infection with shigella flexneri 2a. | rabbits are not usually susceptible to intestinal shigella infection without extensive pretreatment, including starvation and administration of antimicrobial, antimotility, and toxic agents (carbon tetrachloride). most animals infected this way die rapidly and do not always develop colonic lesions and signs of dysentery. we describe here a successful experimental infection in the adult rabbit which does not require preparatory treatment and which reproduced characteristic features of human shige ... | 1995 | 7591070 |
| prevalence of shigella enterotoxin 1 among shigella clinical isolates of diverse serotypes. | shigella enterotoxin 1 (shet1) is a novel, iron-dependent, toxin encoded by chromosomal genes (set1). to determine the prevalence of this enterotoxin, 172 shigella clinical isolates (and 10 enteroinvasive escherichia coli [eiec]) from distant areas worldwide, representing all 4 groups and 45 serotypes of shigella, were screened for set1 by dna colony hybridization and polymerase chain reaction amplification. set1 was present in all 22 shigella flexneri 2a strains tested but was rare in isolates ... | 1995 | 7594690 |
| evaluation of the safety, immunogenicity, and efficacy in healthy adults of four doses of live oral hybrid escherichia coli-shigella flexneri 2a vaccine strain ecsf2a-2. | in previous trials, live invasive escherichia coli-shigella flexneri 2a hybrid vaccine candidate ecsf2a-2, administered to adult volunteers as 3 doses of ca. 2 x 10(9) colony forming units (c.f.u.) spaced over one week, induced fever and/or diarrhea in 11% of subjects and provided only limited protection (36% efficacy) against illness following challenge with virulent s. flexneri 2a. we sought to improve the clinical safety of this vaccine by administering a lower inoculum, and to enhance protec ... | 1995 | 7639017 |
| [the immunomodulating capacity of shigella flexneri 2a bacteria that have lost their invasiveness plasmid]. | an immunosuppressive effect produced by live microbial cells of s. flexneri virulent plasmid-carrying strain 2a 516 (psf 140-) was shown in relation to the formation of splenic cells producing antibodies to heterologous antigen (sheep red blood cells). this effect was most pronounced at an early period (days 4-7) after the infection of mice. on the contrary, avirulent plasmid-free variant (psf 140-), genetically related to s. flexneri strain 2a 516, produced an immunostimulating effect at this p ... | 1995 | 7653137 |
| antibody and cytokine responses in a mouse pulmonary model of shigella flexneri serotype 2a infection. | a murine pulmonary model was used to study the mucosal immune response to shigella flexneri serotype 2a infection. inoculation of balb/cj mice with shigellae via the intranasal route resulted in bacterial invasion of bronchial and alveolar epithelia with concomitant development of acute suppurative bronchiolitis and subsequent development of lethal pneumonia. the pathology of pulmonary lesions resembled the colitis that characterizes shigellosis in humans and primates. significant protection aga ... | 1995 | 7729907 |
| safety and immunogenicity study of the auxotrophic shigella flexneri 2a vaccine sfl1070 with a deleted arod gene in adult swedish volunteers. | the live auxotrophic shigella flexneri 2a vaccine strain sfl1070 with a deleted arod gene was given orally to 37 adult swedish volunteers who received three doses within 5 days. each dose comprised 1 x 10(5) (n = 9), 1 x 10(7) (n = 10), 1 x 10(8) (n = 9) or 1 x 10(9) (n = 9) c.f.u. s. flexneri sfl1070. one volunteer vaccinated with 1 x 10(7) and three vaccinated with 1 x 10(8) c.f.u. reported mild gastrointestinal symptoms after the first dose. vaccination with 1 x 10(9) c.f.u. caused abdominal ... | 1995 | 7762285 |
| shigella enterotoxin 1: an enterotoxin of shigella flexneri 2a active in rabbit small intestine in vivo and in vitro. | culture filtrates of shigella flexneri 2a strain m4243 grown in iron-depleted medium, caused significant fluid accumulation in rabbit ileal loops. also, when tested in ussing chambers, a greater rise in potential difference and short circuit current was seen with such filtrates compared with the medium control. analogous filtrates from two m4243 derivatives lacking the 140-md invasiveness plasmid (either m4243avir or bs103) retained 60-65% of the wild-type enterotoxic activity. ultrafiltration a ... | 1995 | 7769126 |
| a common-source outbreak of shigellosis involving a piped public water supply in northern thai communities. | we report an epidemiological investigation of an explosive common-source water-borne shigellosis outbreak traced to a piped public water system in northern thai communities. in august 1991, 242 cases of acute diarrhoeal illness occurred in sam ngao subdistrict, tak province. about 30% of the cases were culture-positive for multiresistant shigella flexneri 2a. the outbreak affected all age groups, with the highest attack rate (9.4%) in children < 5 years old. the first ten cases occurred during 1 ... | 1995 | 7783269 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| construction of a stable and non-resistant bivalent vaccine candidate strain against shigella flexneri 2a and shigella sonnei. | the e. coli cs3 gene coding for cfa/ii antigen was site-specifically integrated into the asd gene locus of s. flexneri 2a vaccine strain t32, resulting in the inactivation of the asd gene. meanwhile, the gene cluster for s. sonnei o antigen was cloned into a non-resistant expression vector pxl378 to construct the plasmid pxl390. by transforming the asd-mutant of the t32 strain with pxl390, the bivalent vaccine candidate strain fs01 against s. flexneri 2a and s. sonnei was finally obtained. exper ... | 1996 | 8988355 |
| 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 |
| 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 |
| 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 |
| 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 |
| characterization and quantitative analysis of serum igg class and subclass response to shigella sonnei and shigella flexneri 2a lipopolysaccharide following natural shigella infection. | the igg subclass response to shigella sonnei and shigella flexneri 2a lipopolysaccharide (lps) was examined in subjects naturally exposed to these organisms. affinity-purified lps antibodies obtained using a column of shigella lps bound to epoxy-activated sepharose 6b were used as standards to calibrate the serum antibody response to natural shigella infection. the geometric mean concentrations of specific igg in sera from those not exposed to shigella organisms were 7.9 microg/ml against s. son ... | 1997 | 9129076 |
| [morphologic characterization of the contemporary dysentery caused by shigella flexneri 2a]. | there is a tendency in st. petersburg since 1990s to an increase of dysentery morbidity and lethality mainly caused by flexner shigella 2a. morphology of the disease in adults is given on the material of 286 necropsies in 1993-1994 in the s. p. botkin infectious hospital. males (mean age 50 years) and among them chronic alcoholics prevailed; females (mean age 70 years) were frequently with a grave cardiovascular pathology. advanced inflammation (fibrinous, ulcerative and hemorrhagic) of all colo ... | 1997 | 9139607 |
| effect of shigella enterotoxin 1 (shet1) on rabbit intestine in vitro and in vivo. | shigella enterotoxin 1 is a novel enterotoxin elaborated by shigella flexneri 2a that causes fluid accumulation in rabbit ileal loops and a rise in short circuit current in ussing chambers. | 1997 | 9176079 |
| identification of a chromosomal shigella flexneri multi-antibiotic resistance locus which shares sequence and organizational similarity with the resistance region of the plasmid nr1. | the ampicillin resistance gene from shigella flexneri 2a strain ysh6000 was cloned and shown by southern hybridization analysis to be closely linked to the previously cloned streptomycin, chloramphenicol, and tetracycline resistance determinants, which are borne on a chromosomally integrated 99-kb element. analysis of this chromosomal multi-antibiotic resistance locus revealed that it had a high level of sequence and organizational similarity to an equivalent region of the shigella r-plasmid, nr ... | 1997 | 9200219 |
| virulence plasmid instability in shigella flexneri 2a is induced by virulence gene expression. | expression of the predominantly plasmid-encoded virulence regulon of shigella flexneri 2a is induced by growth at 37 degrees c and repressed by growth at 30 degrees c. during growth at 37 degrees c, spontaneous s. flexneri mutants arise which have undergone virulence plasmid curing or rearrangement and no longer display the virulent phenotype. in the laboratory, the unstable nature of the virulence plasmid causes complete loss of virulence in a growing population. we have undertaken an analysis ... | 1997 | 9284138 |
| use of a novel approach, termed island probing, identifies the shigella flexneri she pathogenicity island which encodes a homolog of the immunoglobulin a protease-like family of proteins. | the she gene of shigella flexneri 2a, which also harbors the internal enterotoxin genes set1a and set1b (f. r. noriega, genbank accession no. u35656, 1995) encodes a homolog of the virulence-related immunoglobulin a (iga) protease-like family of secreted proteins, tsh, espc, sepa, and hap, from an avian pathogenic escherichia coli, an enteropathogenic e. coli, s. flexneri 5, and haemophilus influenzae, respectively. to investigate the possibility that this locus was carried on a larger deletable ... | 1997 | 9353040 |
| immunogenicity of ipac-hybrid proteins expressed in the shigella flexneri 2a vaccine candidate sc602. | we have investigated the capacity of live attenuated shigella flexneri strains to act as vectors for the induction of local and systemic antibody responses against heterologous epitopes. the s. flexneri ipac antigen was selected as a carrier protein into which the c3 neutralizing epitope of the poliovirus vp1 protein was inserted in eight sites distributed along ipac. the resulting ipac-c3 hybrid proteins were expressed from recombinant plasmids in the s. flexneri 2a vaccine candidate, sc602. th ... | 1998 | 9423842 |
| "black holes" and bacterial pathogenicity: a large genomic deletion that enhances the virulence of shigella spp. and enteroinvasive escherichia coli. | plasmids, bacteriophages, and pathogenicity islands are genomic additions that contribute to the evolution of bacterial pathogens. for example, shigella spp., the causative agents of bacillary dysentery, differ from the closely related commensal escherichia coli in the presence of a plasmid in shigella that encodes virulence functions. however, pathogenic bacteria also may lack properties that are characteristic of nonpathogens. lysine decarboxylase (ldc) activity is present in approximately 90% ... | 1998 | 9520472 |
| [mechanism of resistance of shigella flexneri 2a resistant to new quinolone antibiotics]. | a shigella flexneri 2a strain, which did not respond clinically or in laboratory tests to treatment with new quinolone derivatives, was isolated for the first time in japan from a patient admitted for diarrhea to a tokyo hospital. the mechanism of resistance was examined by sequencing the quinolone resistance determining region (qrdr) of the gyra (a quinolone target enzyme) gene and by comparing the active efflux mechanisms of two strains isolated from this patient (before hospitalization and af ... | 1998 | 9621565 |
| [interhospital spread of shigella flexneri 2a]. | in this article the results of the study of regularities in the development of outbreak morbidity in shigellosis, caused by s.flexneri 2a, in hospitals are presented. the study was carried out with the use of the method of typing by the plasmid profile. the study showed the continuity of the epidemic process in the foci which appeared at intervals considerably exceeding the incubation period. the fact of the interhospital spread of s.flexneri 2a was established. the strain causing the disease wa ... | 1998 | 9700878 |
| [genotyping of shigella flexneri 2a strains isolated from patients with acute dysentery in st. petersburg]. | polymerase chain reaction with universal primers (up-pcr) was used for the genotyping of 76 s.flexneri 2a cultures isolated from patients with acute dysentery in infectious and psychoneurological hospitals of st. petersburg. 9 types were determined, and each of them included cultures with identical up-pcr patterns. the population of the infective agent was more heterogeneous in psychoneurological hospitals where the change of types was registered in may-september 1995. some of these types were p ... | 1998 | 9700887 |
| [a case of bacillary dysentery caused by new quinolone-resistant shigella flexneri 2a]. | a 73-year-old male was admitted to our hospital because of detection of shigella flexneri 2a from his stool. antimicrobial treatment with levofloxacin (lvfx) was started, but could not eliminate the organism in the stool. in the examination of drug susceptibility, this strain was highly resistant to all new quinolones. the minimal inhibitory concentration of norfloxacin, ofloxacin and ciprofloxacin to this strain was 12.5 micrograms/ml, 6.25 micrograms/ml and 6.25 micrograms/ml, respectively. th ... | 1998 | 9796193 |
| establishment of unipolar localization of icsa in shigella flexneri 2a is not dependent on virulence plasmid determinants. | unipolar localization of icsa on the surface of shigella flexneri is required for efficient formation of actin tails and protrusions in infected eucaryotic cells. lipopolysaccharide (lps) mutations have been demonstrated to affect either the establishment or the maintenance of icsa in a unipolar location, although the mechanism is unknown. in order to analyze the contribution of virulence plasmid determinants on the unipolar localization of icsa, we examined the localization of icsa expressed fr ... | 1999 | 9864236 |
| short-chain fatty acids improve clinical, pathologic, and microbiologic features of experimental shigellosis. | because of the metabolic and antibacterial actions of short-chain fatty acids (scfa), their roles in modifying the clinicopathologic features of shigellosis were evaluated in a rabbit model of shigellosis. acute colitis was induced in adult rabbits by intracolonic administration of shigella flexneri 2a. after 24 h, rabbits were given 6-h colonic infusions of scfa (acetate, propionate, n-butyrate; 60:30:40 mm) or scfa-free solution (control); groups of rabbits were killed in batches of 2 or 3 ani ... | 1999 | 9878023 |
| adaptive immune response to shigella flexneri 2a cydc in immunocompetent mice and mice lacking immunoglobulin a. | shigella flexneri cydc, which is deficient in cytochrome bd, was rapidly cleared from the lungs of intranasally inoculated mice and was sereny negative, yet it induced 93% protection against challenge with wild-type s. flexneri. mice that lack immunoglobulin a (iga) were fully protected, suggesting that iga may not be required for adaptive immunity in this model system. | 1999 | 10085048 |
| killed oral shigella vaccine made from shigella flexneri 2a protects against challenge in the rabbit model of shigellosis. | the protective efficacy of an orally administered heat-killed virulent strain of shigella flexneri 2a (5 weekly oral doses) was evaluated in 25 rabbits (14 immunized and 11 non-immunized controls) against challenge with the same strain of shigella using the rabbit model of shigellosis. all 11 non-immunized rabbits developed bloody diarrhoea following challenge and 6 (54%) died. none of the 14 immunized rabbits developed diarrhoea (all had pellet stools) but 3 (21%) died from causes not associate ... | 1999 | 10102148 |
| safety and immunogenicity of shigella sonnei and shigella flexneri 2a o-specific polysaccharide conjugates in children. | o-specific polysaccharide conjugates of shigellae were safe and immunogenic in young adults, and a shigella sonnei conjugate conferred protection [1-3]. shigellosis is primarily a disease of children; therefore, the safety and immunogenicity of s. sonnei and shigella flexneri 2a conjugates were studied in 4- to 7-year-old children. local and systemic reactions were minimal. the first injection of both conjugates elicited significant rises in geometric mean levels of serum igg only to the homolog ... | 1999 | 10228084 |
| vaccination against shigellosis with attenuated shigella flexneri 2a strain sc602. | the shigella flexneri 2a sc602 vaccine candidate carries deletions of the plasmid-borne virulence gene icsa (mediating intra- and intercellular spread) and the chromosomal locus iuc (encoding aerobactin) (s. barzu, a. fontaine, p. j. sansonetti, and a. phalipon, infect. immun. 64:1190-1196, 1996). dose selection studies showed that sc602 causes shigellosis in a majority of volunteers when 3 x 10(8) or 2 x 10(6) cfu are ingested. in contrast, a dose of 10(4) cfu was associated with transient feve ... | 1999 | 10377124 |
| thymic independence of adaptive immunity to the intracellular pathogen shigella flexneri serotype 2a. | shigella flexneri is a facultative intracellular pathogen. while immunity to several intracellular pathogens is mediated by t lymphocytes, it is unknown whether cellular immune responses are important to adaptive immunity to s. flexneri. we show that vaccination with s. flexneri serotype 2a confers protection to mice that lack t lymphocytes or gamma interferon (ifn-gamma), specific depletion of t lymphocytes does not alter the protection, and adoptive transfer of splenocytes from vaccinated mice ... | 1999 | 10417163 |
| novel self-sampling culture method to monitor excretion of live, oral shigella flexneri 2a vaccine sc602 during a community-based phase 1 trial. | a culture technique for assessing the excretion of live enteric vaccines was developed and verified during an outpatient safety trial of the shigella flexneri 2a sc602 vaccine. preliminary studies showed that sc602 could be recovered on hektoen enteric (he) agar plates that had been inoculated with seeded stools in one quadrant, held for up to 48 hours, streaked for isolation, and incubated for 24 +/- 6 hours. recovery results on he plates held at 4 degrees c and 25 degrees c were comparable; ho ... | 1999 | 10444027 |
| quantitative analysis of igg class and subclass and iga serum response to shigella sonnei and shigella flexneri 2a polysaccharides following vaccination with shigella conjugate vaccines. | it has been recently reported that a conjugate vaccine composed of the o-specific polysaccharide of s. sonnei bound to pseudomonas aeruginosa recombinant exoprotein a (repa) conferred 74% protection against s. sonnei shigellosis. in the present study affinity purified shigella antibodies were used as standards to quantify and characterize the serum antibody response to vaccination with shigella sonnei or shigella flexneri 2a polysaccharide conjugated to repa. the geometric mean concentrations of ... | 1999 | 10462247 |
| 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 |
| 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 |
| 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 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 |
| 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 |
| characterization of the genes encoding the shea haemolysin in escherichia coli o157:h7 and shigella flexneri 2a. | 2000 | 10865950 | |
| 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 |
| genetic organization of the she pathogenicity island in shigella flexneri 2a. | in this study we report the complete nucleotide sequence and genetic organization of the she pathogenicity island (pai) of shigella flexneri 2a strain ysh6000t. the 46 603 bp she pai is situated adjacent to the 3' terminus of the phev trna gene and includes an imperfect direct repeat of the 3'-terminal 22 bp of the phev gene at the right boundary of the pai. the she pai carries a bacteriophage p4-like integrase gene within the phev -proximal boundary of the pai, intact and truncated mobile genet ... | 2001 | 11162180 |
| safety and immunogenicity of improved shigella o-specific polysaccharide-protein conjugate vaccines in adults in israel. | data suggest that the o-specific polysaccharide (o-sp) domain of the lipopolysaccharide (lps) of shigella species is both an essential virulence factor and a protective antigen and that a critical level of serum immunoglobulin g (igg) to this antigen will confer immunity to shigellosis. because covalent attachment of polysaccharides to proteins increases their immunogenicity, especially in infants and in young children, the o-sp of shigella species were bound to medically useful proteins, and th ... | 2001 | 11179298 |
| molecular epidemiology of a shigella flexneri outbreak in a mountainous township in taiwan, republic of china. | an outbreak of shigellosis occurred in a township of nantou conuty in central taiwan from august to october in 1996. the infections extended to two neighboring townships and continued to the end of 1996. forty cases were confirmed during the period, in contrast to only one confirmed case in nantou county in 1996 before the outbreak. all of these 41 cases in 1996 were identified as infections with shigella flexneri serotype 2a. in order to trace the source of the infections, the 41 isolates recov ... | 2001 | 11230426 |
| attenuated shigella flexneri 2a delta guaba strain cvd 1204 expressing enterotoxigenic escherichia coli (etec) cs2 and cs3 fimbriae as a live mucosal vaccine against shigella and etec infection. | to construct a prototype hybrid vaccine against shigella and enterotoxigenic escherichia coli (etec), the genes encoding the production of etec cs2 and cs3 fimbriae were isolated and expressed in attenuated shigella flexneri 2a guaba strain cvd 1204. the cs2 cota to -d genes, isolated from etec strain c91f, and the cs3 csta to -h genes, subcloned from plasmid pcs100, were cloned into ~15-copy-number-stabilized pga1 behind the osmotically regulated ompc promoter, resulting in high expression of b ... | 2001 | 11292735 |