Publications

proteolytic inhibition of salmonella enterica serovar typhimurium-induced activation of the mitogen-activated protein kinases erk and jnk in cultured human intestinal cells.	bromelain, a mixture of cysteine proteases from pineapple stems, blocks signaling by the mitogen-activated protein (map) kinases extracellular regulated kinase 1 (erk-1) and erk-2, inhibits inflammation, and protects against enterotoxigenic escherichia coli infection. in this study, we examined the effect of bromelain on salmonella enterica serovar typhimurium infection, since an important feature of its pathogenesis is its ability to induce activation of erk-1 and erk-2, which leads to internal ...	2002	11748167
comparison of inflammation, organ damage, and oxidant stress induced by salmonella enterica serovar muenchen flagellin and serovar enteritidis lipopolysaccharide.	gram-negative sepsis is related to the activation of interconnected inflammatory cascades in response to bacteria and their products. recent work showed that flagellin, the monomeric subunit of bacterial flagella, triggers innate immune responses mediated by toll-like receptor 5. here, we compared the effects of salmonella enterica serovar enteritidis lipopolysaccharide (lps) and recombinant salmonella enterica serovar muenchen flagellin administered intravenously (100 microg) to mice. flagellin ...	2002	11748182
characterization of the murine t-lymphocyte response to salmonella enterica serovar typhimurium infection.	infection of mice with salmonella enterica serotype typhimurium induces a strong th1 cell response that is central for the control of infection. we infected mice of a resistant background with a virulent strain of s. enterica serovar typhimurium and analyzed the kinetics and magnitude of the t-cell response. after infection, the majority of cd4(+) and cd8(+) splenocytes acquired an activated phenotype, as indicated by expression levels of cd44 and cd62l. in addition, after 3 to 4 weeks of infect ...	2002	11748183
role of the recbcd recombination pathway in salmonella virulence.	mutants of salmonella enterica lacking the recbc function are avirulent in mice and unable to grow inside macrophages (n. a. buchmeier, c. j. lipps, m. y. h. so, and f. heffron, mol. microbiol. 7:933-936, 1993). the virulence-related defects of recbc(-) mutants are not suppressed by sbcb and sbccd mutations, indicating that activation of the recf recombination pathway cannot replace the virulence-related function(s) of recbcd. functions of the recf pathway such as recj and recf are not required ...	2002	11751841
effect of chromosome location on bacterial mutation rates.	in previous comparisons of enterobacterial sequences, synonymous substitution rates were higher in genes closer to the replication terminus, suggesting that mutation rates increase with distance from the replication origin. in order to directly test for the effects of chromosomal location on the rates of point mutations, we assayed the reversion rates of two lacz alleles inserted at four positions in the salmonella enterica chromosome. mutation rates at an intermediate locus were significantly h ...	2002	11752193
competitive exclusion of salmonella enterica serovar enteritidis by lactobacillus crispatus and clostridium lactatifermentans in a sequencing fed-batch culture.	competitive exclusion of salmonella enterica serovar enteritidis by a mixed culture of lactobacillus crispatus and clostridium lactatifermentans was studied in a sequencing fed-batch reactor mimicking the cecal ecophysiology of broiler chickens. growth of serovar enteritidis was inhibited by a mixed culture of l. crispatus and c. lactatifermentans at ph 5.8 but not by a monoculture of l. crispatus at the same ph. moreover, experiments performed at ph 7.0 did not show growth inhibition of serovar ...	2002	11823190
efficient insertion mutagenesis strategy for bacterial genomes involving electroporation of in vitro-assembled dna transposition complexes of bacteriophage mu.	an efficient insertion mutagenesis strategy for bacterial genomes based on the phage mu dna transposition reaction was developed. incubation of mua transposase protein with artificial mini-mu transposon dna in the absence of divalent cations in vitro resulted in stable but inactive mu dna transposition complexes, or transpososomes. following delivery into bacterial cells by electroporation, the complexes were activated for dna transposition chemistry after encountering divalent metal ions within ...	2002	11823210
selective amplification of tyv (rfbe), prt (rfbs), viab, and flic genes by multiplex pcr for identification of salmonella enterica serovars typhi and paratyphi a.	the pcr primers for o, h, and vi antigen genes, tyv (rfbe), prt (rfbs), flic-d, flic-a, and viab, were designed and used for the rapid identification of salmonella enterica serovars typhi and paratyphi a with multiplex pcr. the results showed that all the clinical isolates examined of salmonella serovars typhi and paratyphi a were accurately identified by this assay.	2002	11825983
[reactive arthritis after recent infection with group a beta-hemolytic streptococcus and group b salmonella].		2002	11827664
[purulent pericarditis due to salmonella enterica subsp. arizonae].		2002	11820989
differences and similarities among experts' opinions on salmonella enterica dynamics in swine pre-harvest.	a workshop was conducted to elicit expert opinion on infection status and transmission of salmonella in pigs at the farm of origin, during transport and during lairage. a second objective was to compare opinions regarding risk factors for salmonella introduction and control at the farm level between experts from different countries. thirty-six experts from 11 countries filled in a paper-and-pencil questionnaire during an international conference. experts from all countries agreed on the risk of ...	2002	11821133
herd-level diagnosis for salmonella enterica subsp. enterica serovar dublin infection in bovine dairy herds.	herd-level sensitivities of bacteriological and serological methods were compared in 79 bovine dairy herds, recently infected with salmonella enterica subsp. enterica serovar dublin. all farms experienced clinical signs of salmonellosis for the first time and had no history of vaccination against salmonellosis. at the start of the study, infection with serovar dublin was confirmed with at least one positive bacteriologic culture for serovar dublin from a clinical case (gold standard for herd inf ...	2002	11821135
the new classification system for slaughter-pig herds in the danish salmonella surveillance-and-control program.	the danish surveillance-and-control program for salmonella in slaughter pigs was introduced in 1995. the key element of the program is a quick and correct identification of herds with high seroprevalence. after 5 years, the classification scheme was evaluated--and a revision was made. data from two salmonella screenings including a total of 1902 slaughter pig herds were used. for each herd, information was available on salmonella status based on both microbiology and serology. based on analyses ...	2002	11821142
macrophages inhibit salmonella typhimurium replication through mek/erk kinase and phagocyte nadph oxidase activities.	host responses during the later stages of salmonella-macrophage interactions are critical to controlling infection but have not been well characterized. after 24 h of infection, nearly half of interferon-gamma-primed murine raw 264.7 macrophage-like cells infected by salmonella enterica serovar typhimurium contained filamentous bacteria. bacterial filamentation indicates a defect in completing replication and has been previously observed in bacteria responding to a variety of stresses. to unders ...	2002	11821396
excess production of interleukin-12 subunit p40 stimulated by the virulence plasmid of salmonella enterica serovar typhimurium in the early phase of infection in the mouse.	the production of interleukin-12 (il-12) and its subunits in response to salmonella enterica serovar typhimurium infection in the balb/c mouse was examined. unlike wild-type typhimurium, a plasmidless strain, isolated by curing of the virulence plasmid (pstv), did not stimulate excess il-12p40 production. when a tn 5 tagged pstv was transferred back to the plasmidless strain, the ability to stimulate il-12p40 production was restored. however, a strain harbouring another tn50pstv failed to stimul ...	2002	11782117
the starvation-stress response of salmonella enterica serovar typhimurium requires sigma(e)-, but not cpxr-regulated extracytoplasmic functions.	starvation of salmonella enterica serovar typhimurium (s. typhimurium) for an exogenous source of carbon and energy (c-starvation) induces the starvation-stress response (ssr). the ssr functions to (i) maintain viability during long-term c-starvation and (ii) generate cross-resistance to other environmental stresses. the ssr is, at least partially, under the control of the alternative sigma factor, sigma(s). it is hypothesized that c-starvation causes cell envelope stresses that could induce the ...	2002	11782504
the atp-dependent lon protease of salmonella enterica serovar typhimurium regulates invasion and expression of genes carried on salmonella pathogenicity island 1.	an early step in the pathogenesis of salmonella enterica serovar typhimurium infection is bacterial penetration of the intestinal epithelium. penetration requires the expression of invasion genes found in salmonella pathogenicity island 1 (spi1). these genes are controlled in a complex manner by regulators in spi1, including hila and invf, and those outside spi1, such as two-component regulatory systems and small dna-binding proteins. we report here that the expression of invasion genes and the ...	2002	11741864
transduction-mediated transfer of unmarked deletion and point mutations through use of counterselectable suicide vectors.	a challenge in strain construction is that unmarked deletion and nucleotide substitution alleles generally do not confer selectable phenotypes. we describe here a rapid and efficient strategy for transferring such alleles via generalized transduction. the desired allele is first constructed and introduced into the chromosome by conventional allelic-exchange methods. the suicide vector containing the same allele is then integrated into the mutant chromosome, generating a tandem duplication homozy ...	2002	11741872
interactions of salmonella enterica serovar muenchen with macrophages of the turtle trachemys scripta scripta.	interactions of salmonella with macrophages have been studied in birds and, most extensively, in mammals. in these homeothermic animals, interactions between salmonella and macrophages are characterized by the following processes. after macropinocytosis, spacious phagosomes are formed within the macrophage. partial inhibition of phagosome-lysosome fusion and resistance to the formation of reactive oxygen species and reactive nitrogen intermediates enable the bacterium to survive and even multipl ...	2002	11755678
the emergence in taiwan of fluoroquinolone resistance in salmonella enterica serotype choleraesuis.	salmonella enterica serotype choleraesuis is a cause of serious systemic infections. because fluoroquinolones are the drug of choice for the treatment of severe salmonella infections, the emergence and dissemination of fluoroquinolone-resistant s. enterica serotype choleraesuis have clinical consequences.	2002	11832529
characterization of the propionyl-coa synthetase (prpe) enzyme of salmonella enterica: residue lys592 is required for propionyl-amp synthesis.	the propionyl-coa synthetase (prpe) enzyme of salmonella enterica catalyzes the first step of propionate catabolism, i.e., the activation of propionate to propionyl-coa. the prpe enzyme was purified, and its kinetic properties were determined. evidence is presented that the conversion of propionate to propionyl-coa proceeds via a propionyl-amp intermediate. kinetic experiments demonstrated that propionate was the preferred acyl substrate (kcat/km = 1644 mm(-1) x s(-1)). adenosine 5'-propyl phosp ...	2002	11841231
pdua is a shell protein of polyhedral organelles involved in coenzyme b(12)-dependent degradation of 1,2-propanediol in salmonella enterica serovar typhimurium lt2.	salmonella enterica forms polyhedral organelles involved in coenzyme b(12)-dependent 1,2-propanediol degradation. these organelles are thought to consist of a proteinaceous shell that encases coenzyme b(12)-dependent diol dehydratase and perhaps other enzymes involved in 1,2-propanediol degradation. the function of these organelles is unknown, and no detailed studies of their structure have been reported. genes needed for organelle formation and for 1,2-propanediol degradation are located at the ...	2002	11844753
salmonella enterica serovar typhimurium resistance to bile: identification and characterization of the tolqra cluster.	salmonella enterica serovar typhimurium is resistant to the action of bile salts, and resistance to bile is enhanced in strains in which the phop-phoq (phopq) two-component regulatory system has been activated. to identify genes necessary for bile resistance, mudj transposon mutagenesis was performed on a strain containing a phop mutation that results in constitutive expression of phop-activated genes. after screening >10,000 mutants for the loss of growth on luria-bertani broth-bile plates, 14 ...	2002	11844755
transcription of the ssrab regulon is repressed by alkaline ph and is independent of phopq and magnesium concentration.	the salmonella pathogenicity island 2 (spi-2) type iii secretion system is expressed by intracellular bacteria and translocates effector proteins across the vacuolar membrane. signals sensed by salmonella enterica serovar typhimurium in the intracellular compartment activate spi-2 gene expression through the two-component regulatory system ssrab. the effects of environmental and genetic signals on expression of the ssrab-regulated gene ssph2 were examined. ssrab-dependent activation of ssph2 was ...	2002	11844786
inactivation of foodborne pathogens in milk using dynamic high pressure.	improving the microbiological safety of perishable foods is currently a major preoccupation in the food industry. the aim of this study was to investigate the inactivation of three major food pathogens (listeria monocytogenes [lsd 105-1], escherichia coli o157:h7 [atcc 35150], and salmonella enterica serotype enteritidis atcc [13047]) by dynamic high pressure (dhp) in order to evaluate its potential as a new alternative for the cold pasteurization of milk. the effectiveness of dhp treatment agai ...	2002	11848566
occurrence of salmonella enterica serotype typhimurium dt104a in retail ground beef.	surveillance data of cattle and human isolates of salmonella enterica serovar typhimurium dt104 indicate that this pathogen emerged worldwide in the 1980s, particularly in cattle. studies were conducted to determine the prevalence of salmonella typhimurium dt104 in ground beef. samples were also tested for the presence of generic escherichia coli. a total of 404 fresh ground beef samples obtained at retail stores from new york, san francisco, philadelphia, denver, atlanta, houston, and chicago w ...	2002	11848574
identification of salmonella enteritidis outer membrane proteins expressed during attachment to human intestinal epithelial cells.	to express and identify the salmonella enterica ser. enteritidis outer membrane proteins that are involved in the attachment to human intestinal epithelial cells.	2002	11849343
salmonella enterica serotype enteritidis phage types 4, 7, 6, 8, 13a, 29 and 34: a comparative analysis of genomic fingerprints from geographically distant isolates.	to evaluate genetic heterogeneity in the most common phage types of salmonella enterica serovar enteritidis.	2002	11849346
the prevalence and dynamics of salmonella enterica iiib 61:k:1,5,(7) in sheep flocks in norway.	fifty randomly selected sheep flocks from a region in central norway were sampled in december 1999 to determine the flock prevalence of salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) (s. iiib 61:k:1,5,(7)). from each flock, 15-41 rectal swabs were collected from individual sheep of different age groups and examined for s. iiib 61:k:1,5,(7). positive flocks were visited again in january-april and each time, rectal swabs from the same animals were collected and examined for this sp ...	2002	11849721
prevalence of a salmonella subspecies diarizonae in norwegian sheep herds.	we studied the prevalence of salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) (s. iiib 61:k:1,5,(7)) in 133 norwegian sheep herds from throughout the country. we used a nested case-control study to identify major risk factors. two pooled samples (one from lambs and one from adult sheep) were collected from each herd from (10 different) abattoirs. the regional prevalence varied from 0 to 45%, and was more prevalent in adults than in lambs. sixteen of the 133 herds tested positive to ...	2002	11849722
abomasitis associated with multiple antibiotic resistant salmonella enterica serotype typhimurium phagetype dt104.	salmonella enterica serotype typhimurium phagetype dt104 is a multiple antibiotic resistant pathogen that has been purported to be more pathogenic than other salmonella. in this study, we evaluated the possibility that dt104 is the causative agent of veal calf abomasitis observed in four independent outbreaks of salmonellosis. this study was undertaken to determine if the outbreaks might be due to hypervirulent s. enterica serotype typhimurium phagetype dt104 (dt104) since salmonella does not us ...	2002	11852190
type iii secretion of salmonella enterica serovar typhimurium translocated effectors and ssefg.	the type iii secretion system (ttss) encoded by salmonella enterica serovar typhimurium pathogenicity island 2 (spi2) is employed by salmonella enterica for interaction with host cells during the intracellular phase of pathogenesis. this ttss secretes a set of spi2-encoded proteins in vitro and translocates salmonella serovar typhimurium translocated effectors (ste) that are encoded by genes outside of spi2 into host cells. using an epitope-tagging approach, we analyzed secretion of proteins by ...	2002	11854226
extracellular antigens from salmonella enteritidis induce effective immune response in mice after oral vaccination.	we have studied polyacryl starch microparticles as an adjuvant in oral vaccination in mice. secreted antigens from salmonella enterica serovar enteritidis were administered covalently conjugated to microparticles, or as free antigens, orally or intramuscularly and evaluated for their immunogenicity and ability to elicit protective immune response against an oral challenge with live serovar enteritidis. the highest immunoglobulin m (igm)-plus-igg titers were obtained in the groups immunized with ...	2002	11854230
lipopolysaccharide-specific but not anti-flagellar immunoglobulin a monoclonal antibodies prevent salmonella enterica serotype enteritidis invasion and replication within hep-2 cell monolayers.	the protective potential of immunoglobulin a (iga) monoclonal antibodies (mabs) directed against o and h antigens of salmonella enterica serotype enteritidis to prevent bacterial adhesion to and invasion of hep-2 cells was evaluated. although anti-flagellar iga mabs showed strong agglutinating capacities, they did not protect cell monolayers. in contrast, iga mabs specific for the o:9 epitope of salmonella lipopolysaccharide antigen alone prevented s. enterica serotype enteritidis entry and repl ...	2002	11854252
analyses of the evolutionary distribution of salmonella translocated effectors.	the type iii secretion system encoded by salmonella pathogenicity island 2 (spi2) translocates salmonella translocated effectors (ste) into host cells. ste are encoded by genes outside of spi2. the distribution of ste loci within the salmonellae was investigated. in contrast to the spi2 locus that is conserved within salmonella enterica, ste loci show a variable distribution. in addition to other virulence determinants, the possession of various sets of ste loci may contribute to the different h ...	2002	11854253
the invasion-associated type iii secretion system of salmonella enterica serovar typhimurium is necessary for intracellular proliferation and vacuole biogenesis in epithelial cells.	type iii secretion systems (ttss) are used by gram-negative pathogens to translocate proteins into eukaryotic host cells. salmonella enterica serovar typhimurium (s. typhimurium) has two of these specialized systems, which are encoded on separate salmonella pathogenicity islands (spi-1 and spi-2) and translocate unique sets of effectors. the specific roles of these systems in salmonella pathogenesis remain undefined, although spi-1 is required for bacterial invasion of epithelial cells and spi-2 ...	2002	11856172
immunogenicity of chi4127 phop- salmonella enterica serovar typhimurium in dogs.	salmonellae are commonly isolated from dogs. the number of dogs infected with salmonella spp. is surprisingly high and greater than the incidence of clinical disease would suggest. salmonellosis is common in greyhound kennels. morbidity can approach 100% in puppies and the mortality ranges to nearly 40%. to date, there has been little effort to evaluate the feasibility of a vaccine for control of this disease in dogs. in the studies described here, an attenuated strain of salmonella enterica ser ...	2002	11858870
attenuated salmonella enterica serovar typhi live vector with inducible chromosomal expression of the t7 rna polymerase and its evaluation with reporter genes.	attenuated salmonella strains with defined gene deletions have been extensively evaluated as suitable live carriers of passenger antigens. a number of strategies for antigen delivery by these strains have been attempted, ranging from plasmid-based to chromosomal integration systems. we report here the chromosomal integration of the t7 rna polymerase gene (t7pol) in the attenuated strain salmonella enterica serovar typhi (salmonella typhi) cvd908 (aroc(-), arod(-)). the t7pol gene was amplified b ...	2002	11982332
invasive food poisoning caused by salmonella oranienburg.		2002	11982885
bromoperoxidase activity of vanadate-substituted acid phosphatases from shigella flexneri and salmonella enterica ser. typhimurium.	vanadium haloperoxidases and the bacterial class a nonspecific acid phosphatases have a conserved active site. it is shown that vanadate-substituted recombinant acid phosphatase from shigella flexneri (phon-sf) and salmonella enterica ser. typhimurium (phon-se) in the presence of h2o2 are able to oxidize bromide to hypobromous acid. vanadate is essential for this activity. the kinetic parameters for the artificial bromoperoxidases have been determined. the km value for h2o2 is about the same as ...	2002	11985594
increasing quinolone resistance in salmonella enterica serotype enteritidis.	until recently, salmonella enterica serotype enteritidis has remained sensitive to most antibiotics. however, national surveillance data from denmark show that quinolone resistance in s. enteritidis has increased from 0.8% in 1995 to 8.5% in 2000. these data support concerns that the current use of quinolone in food animals leads to increasing resistance in s. enteritidis and that action should be taken to limit such use.	2002	11996688
[will the effectiveness of the immunization of chicks with live salmonella vaccines be affected by maternal antibodies?].	in the progeny of breeder birds which had been vaccinated with live salmonella typhimurium and inactivated salmonella enteritidis vaccines, the caecal and systemic colonisation by a live salmonella enteritidis and a live salmonella typhimurium vaccine was studied. the efficacy of the oral immunisation of chicks from vaccinated and non-vaccinated breeders with a live salmonella enteritidis vaccine on day 1 of age was studied by an experimental challenge with salmonella enteritidis on day 30 of ag ...	2002	11998364
phage typing and pfge pattern analysis as tools for epidemiological surveillance of salmonella enterica serovar bovismorbificans infections.	some years ago, an increase in the number of sporadic cases and outbreaks of salmonellosis due to s. enterica serovar bovismorbificans was observed in several european countries including finland, sweden, england/wales, austria, and germany. in order to understand the recent spread of this serovar and to trace the route of infection back to its source, it was considered necessary to subtype s. bovismorbificans isolates. using phage typing (newly described here) and molecular fingerprinting (pfge ...	2002	12002528
is200 fingerprinting of salmonella enterica serotype abortusovis strains isolated in iran.	salmonella enterica serovar abortusovis is one of the most common pathogens responsible for abortion in sheep. in iran, the spread of abortusovis is highly dependent on the nomadic life style. in this study we performed is200 fingerprinting to identify the clonal lines circulating in iran. all the isolates contained 4 or 5 copies of the transposon and could be classified in 4 genotypes. a single genotype was highly prevalent and very likely it has circulated in iran since 1970. all the isolates ...	2002	12002552
composite integron array generated by insertion of an orf341-type integron within a tn21-like element.	two class 1 integrons, in-t1 and in-t2, were previously identified in incfi plasmids of salmonella enterica serotype typhimurium. molecular analysis revealed a close physical link between the two integrons. in-t1 is preceded by the transposase genes of tn21, whereas in-t2 is located downstream the 3'-conserved segment (3'-cs) of in-t1, in a head-to-tail configuration. in-t1 shows a peculiar sequence downstream the 3'-cs, containing an extended version of the open reading frame known as orf341 (r ...	2002	12002644
nucleotide and amino acid sequences of orit-tram-traj-tray-traa-tral regions and mobilization of virulence plasmids of salmonella enterica serovars enteritidis, gallinarum-pullorum, and typhimurium.	the virulence plasmid of salmonella enterica serovar gallinarum-pullorum (pspv) but not those of salmonella enterica serovars enteritidis (psev) and typhimurium (pstv) can be readily mobilized by an f or f-like conjugative plasmid. to investigate the reason for the difference, the orit-tram-traj-tray-traa-tral regions of the three salmonella virulence plasmids (psvs) were cloned and their nucleotide and deduced amino acid sequences were examined. the cloned fragments were generally mobilized mor ...	2002	12003924
argr-independent induction and argr-dependent superinduction of the astcadbe operon in escherichia coli.	for escherichia coli, growth in the absence of ammonia is termed nitrogen limited and results in the induction of genes that assimilate other nitrogen sources, a response mediated by sigma(54) and nitrogen regulator i (nr(i), also called ntrc). the astcadbe operon, which is required for growth with arginine as the sole nitrogen source, is moderately expressed during general nitrogen limitation and maximally expressed in the presence of arginine. the operon is also induced in stationary phase. pr ...	2002	12003934
fluoroquinolone resistance in salmonella serovars isolated from humans and food animals.	quinolone-resistant salmonella enterica usually contain a mutation in gyra within the region encoding the quinolone resistance determining region of the a subunit of dna gyrase. these mutations confer substitutions analogous to escherichia coli ser83-->phe and asp87-->gly or tyr, or a novel mutation resulting in ala119-->glu or val. mutations in gyrb are rare, and no mutations in parc or pare have been described. quinolone-resistant salmonella can also be cross-resistant to other agents includin ...	2002	12007640
characterisation of the diol dehydratase pdu operon of lactobacillus collinoides.	the three genes (pducde) encoding the diol dehydratase of lactobacillus collinoides were sequenced. they exhibited strong identities with the ddrabc and pducde genes of klebsiella oxytoca and salmonella enterica, respectively. these genes are part of a putative operon with at least four other genes. an eighth open reading frame was identified as homologous to the pocr gene (encoding the operon regulatory protein). although the enzyme was detected in exponential growth phase, pducde activity was ...	2002	12007656
development of a baculovirus expression system for soluble porcine tumor necrosis factor receptor type i and soluble porcine tumor necrosis factor receptor type i-igg fusion protein.	tumor necrosis factor-alpha (tnf-alpha) is a key mediator of inflammatory responses and gram-negative bacterial sepsis, but the role that it plays during salmonella enterica species bacterial infections in swine has not yet been elucidated. to facilitate studies on the role of tnf-alpha on the pathology associated with salmonella infections in pigs, recombinant soluble porcine tnf receptor type i (rsptnf-ri) and soluble tnf receptor type i fused to the fc region of porcine igg1 (rsptnf-ri-igg) w ...	2002	12007891
temperate phages in salmonella enterica serovar typhimurium: implications for epidemiology.	salmonella enterica serovar typhimurium is the most common salmonella serovar isolated from humans in australia. the most common definitive phage types (dt) include 9, 64 and 135. induction of lysogenic phages from dt 64 with mitomycin c followed by cesium chloride gradient purification, resulted in separation of two populations of phage particles. dna extracted from these particles that was digested with smai showed two distinct patterns of banding. transmission electron microscopy showed that ...	2002	12008917
modified pulsed-field gel electrophoresis method for dna degradation-sensitive salmonella enterica and escherichia coli strains.	a number of s. enterica and e. coli strains appeared sensitive to a rapid dna degradation during the course of pfge pattern analysis. this kind of dna degradation could not be stopped by intensive treatment with proteinase k, formalin treatment, or other modifications of the protocol for the isolation of intact chromosomal dna. however, the application of 100 microm thiourea into the running buffer gave rise to clear-cut pfge patterns and in turn to an overall typeability.	2002	12008918
cytokine expression by attenuated intracellular bacteria regulates the immune response to infection: the salmonella model.	attenuated salmonella strains have shown excellent efficacy as mucosal vaccine delivery systems. in the present report, several recombinant strains of salmonella enterica serovar typhimurium, engineered to express defined murine cytokines, were used to study their potential immunoregulatory capacity in the mouse model of typhoid fever. specifically, recombinant strains expressing il-2 (known as gidil2) or tnf-alpha (gidtnf) were compared with the parental, non-cytokine-secreting, strain (brd509) ...	2002	12009571
combination of pulsed-field gel electrophoresis (pfge) and single-enzyme amplified fragment length polymorphism (saflp) for differentiation of multiresistant salmonella enterica serotype typhimurium.	to assess the combined application of plasmid profile typing, pulsed-field gel electrophoresis (pfge) and pcr-based single-enzyme amplified fragment length polymorphism (saflp) for the differentiation of 18 multiresistant (mr) and one drug-sensitive strain of salmonella enterica serotype typhimurium from humans and food animals.	2002	12010170
sifa, a type iii secreted effector of salmonella typhimurium, directs salmonella-induced filament (sif) formation along microtubules.	a unique feature of salmonella enterica serovar typhimurium (s. typhimurium) is its ability to enter into (invade) epithelial cells and elongate the vacuole it occupies into tubular structures called salmonella-induced filaments (sifs). this phenotype is dependent on sifa, a salmonella virulence factor that requires the spi-2-encoded type iii secretion system for delivery into host cells. previous attempts to study sifa and other type iii secreted proteins have been limited by a lack of suitable ...	2002	12010459
the effect of genomic position on reversion of a lac frameshift mutation (laciz33) during non-lethal selection (adaptive mutation).	in a system described by cairns and foster, starvation of a particular leaky lac mutant (laciz33) in the presence of lactose appears to direct mutation in non-growing cells to sites that allow growth (adaptive mutation). this behaviour requires that the lac operon be located on an f' plasmid. this position effect was investigated by placing the mutant lac operon at many sites in the genome of salmonella enterica (typhimurium; lt2) and testing reversion behaviour. genomic position did not affect ...	2002	12010495
genetic diversity of salmonella enterica serovar paratyphi a from different geographical regions in asia.	subtyping of salmonella paratyphi a isolates from india, pakistan, indonesia and malaysia was carried out by pulsed-field gel electrophoresis (pfge) to assess the extent of genetic diversity of these isolates from different endemic countries.	2002	12010557
role of nitric oxide in host defense in murine salmonellosis as a function of its antibacterial and antiapoptotic activities.	host defense functions of nitric oxide (no) are known for many bacterial infections. in this study, we investigated the antimicrobial effect of no in murine salmonellosis by using inducible no synthase (inos)-deficient mice infected with an avirulent or virulent salmonella enterica serovar typhimurium strain. all inos-deficient mice died of severe septicemia within 6 days after intraperitoneal injection with an avirulent strain (lt2) to which wild-type mice were highly resistant; 50% lethal dose ...	2002	12011007
disruption of the salmonella-containing vacuole leads to increased replication of salmonella enterica serovar typhimurium in the cytosol of epithelial cells.	salmonella enterica serovar typhimurium is a facultative intracellular pathogen that inhabits a vacuolar compartment, called the salmonella-containing vacuole (scv), in infected host cells. maintenance of the scv is accomplished by sifa, and mutants of this salmonella pathogenicity island 2 type iii effector replicate more efficiently in epithelial cells. here we demonstrate that enhanced replication of sifa mutants occurs in the cytosol of these cells. increased replication of wild-type bacteri ...	2002	12011022
characterization of the spv locus in salmonella enterica serovar arizona.	salmonella enterica serovar arizona (s. enterica subspecies iiia) is a common salmonella isolate from reptiles and can cause serious systemic disease in humans. the spv virulence locus, found on large plasmids in salmonella subspecies i serovars associated with severe infections, was confirmed to be located on the chromosome of serovar arizona. sequence analysis revealed that the serovar arizona spv locus contains homologues of spvrabc but lacks the spvd gene and contains a frameshift in spva, r ...	2002	12011028
genomic organization of lps-specific loci.		2002	12014174
factors affecting haemolysin production and congo red binding in salmonella enterica serovar typhimurium dt 98.	differences in haemolysin expression were observed in a strain of salmonella enterica serovar typhimurium definitive phage type (dt) 98 cultured under various conditions. haemolysin expression was optimal in cultures grown micro-aerobically. the zones of haemolysis were wider after longer periods of incubation. haemolysin production varied after growth in the following media (greatest to least): brain heart infusion (bhi) broth > nutrient broth (nb)>trypticase soy broth (tsb)> m-9 glucose medium ...	2002	12018658
characterization of variant salmonella genomic island 1 multidrug resistance regions from serovars typhimurium dt104 and agona.	strains of multidrug-resistant salmonella enterica serovar typhimurium dt104 (dt104) and s. enterica serovar agona (agona) have been found to harbor salmonella genomic island 1 (sgi1), a 43-kb genomic region that contains many of the drug resistance genes. such strains are resistant to ampicillin (pse-1), chloramphenicol/florfenicol (flor), streptomycin/spectinomycin (aada2), sulfonamides (sul1), and tetracycline [tet(g)] (commonly called the acssut phenotype). all five resistance genes are foun ...	2002	12019080
reducing mortality in salmonella enterica serovar typhimurium-infected mice with a tripeptidic serum fraction.	salmonellosis-induced mortality in female swiss webster mice decreased significantly when tripeptidic immunostimulant (tpi) was administered prophylactically. prophylactic benefits developed in a dose-dependent manner wherein 15 mg of tpi given 1 day before challenge reduced mortality by 70%.	2002	12019117
specific gyra mutation at codon 83 in nalidixic acid-resistant salmonella enterica serovar typhi strains isolated from vietnamese patients.		2002	12019140
the sctr of salmonella enterica serova typhimurium encoding a homologue of merr protein is involved in the copper-responsive regulation of cuid.	we have identified the cuid gene in salmonella enterica serova typhimurium that codes for a putative multicopper oxidase. expression of cuid is induced by copper ion and its promoter/operator has sequence similarity to the promoters controlled by the transcriptional regulators of the merr family. we also identified and isolated a gene from s. enterica serova typhimurium that encodes a 138-amino acid residue protein, sctr, a new member of the merr family of transcriptional regulators. transposon- ...	2002	12023084
heterogeneity in expression of lipopolysaccharide by strains of salmonella enterica serotype typhimurium definitive phage type 104 and related phage types.	to investigate lipopolysaccharide (lps) expression in salmonella enterica serotype typhimurium definitive phage type 104 (salmonella typhimurium dt104) and related phage types.	2002	12028424
regulation of salmonella enterica serovar typhimurium mnth transcription by h(2)o(2), fe(2+), and mn(2+).	mnth, a bacterial homolog of mammalian natural resistance associated macrophage protein 1 (nramp1), is a primary transporter for mn(2+) influx in salmonella enterica serovar typhimurium and escherichia coli. s. enterica serovar typhimurium mnth contributes to h(2)o(2) resistance and is important for full virulence. consistent with its phenotype and function, mnth is regulated at the transcriptional level by both h(2)o(2) and substrate cation. we have now identified three trans-acting regulatory ...	2002	12029030
sitabcd is the alkaline mn(2+) transporter of salmonella enterica serovar typhimurium.	mnth, a bacterial homolog of the mammalian natural resistance-associated macrophage protein 1 (nramp1), is a primary mn(2+) transporter of salmonella enterica serovar typhimurium and escherichia coli. s. enterica serovar typhimurium mnth expression is important for full virulence; however, strains carrying an mnth deletion are only partially attenuated and display no obvious signs of mn(2+) deficiency. we noted that promoter sequences for mnth and for the putative fe(2+) transporter sitabcd appe ...	2002	12029031
mig-14 is a salmonella gene that plays a role in bacterial resistance to antimicrobial peptides.	it was previously demonstrated that the mig-14 gene of salmonella enterica serovar typhimurium is necessary for bacterial proliferation in the liver and spleen of mice following intragastric inoculation and that mig-14 expression, which is induced within macrophages, is under the control of the global regulator phop. here we demonstrate that the mig-14 promoter is induced by growth in minimal medium containing low magnesium or acidic ph, consistent with regulation by phop. in addition, mig-14 is ...	2002	12029036
substrate recognition properties of oligopeptidase b from salmonella enterica serovar typhimurium.	oligopeptidase b (opdb) is a serine peptidase broadly distributed among unicellular eukaryotes, gram-negative bacteria, and spirochetes which has emerged as an important virulence factor and potential therapeutic target in infectious diseases. we report here the cloning and expression of the opdb homologue from salmonella enterica serovar typhimurium and demonstrate that it exhibits amidolytic activity exclusively against substrates with basic residues in p(1). while similar to its eukaryotic ho ...	2002	12029050
genomewide identification of proteins secreted by the hrp type iii protein secretion system of pseudomonas syringae pv. tomato dc3000.	the ability of pseudomonas syringae pv. tomato dc3000 to be pathogenic on plants depends on the hrp (hypersensitive response and pathogenicity) type iii protein secretion system and the effector proteins it translocates into plant cells. through iterative application of experimental and computational techniques, the dc3000 effector inventory has been substantially enlarged. five homologs of known avirulence (avr) proteins and five effector candidates, encoded by genes with putative hrp promoters ...	2002	12032338
inorganic polyphosphate is essential for long-term survival and virulence factors in shigella and salmonella spp.	the importance of inorganic polyphosphate (poly p) and poly p kinase (ppk), the enzyme principally responsible for its synthesis, has been established previously for stationary-phase survival of escherichia coli and virulence in pseudomonas aeruginosa. the gene (ppk) that encodes ppk is highly conserved among many bacterial pathogens, including shigella and salmonella spp. in view of the phylogenetic similarity of the enteropathogens and the frequency with which virulence factors are expressed i ...	2002	12032342
microsatellites linked to salmonella enterica serovar enteritidis burden in spleen and cecal content of young f1 broiler-cross chicks.	contamination of poultry and poultry products by salmonella enterica serovar enteritidis (se) continues to be problematic even though biosafety management practices have aided in reduction of the se burden. identification of molecular markers linked to disease resistance loci would further reduce se burden by enabling selection for genetic resistance. the objectives of this study were therefore to evaluate specific genomic regions for resistance to se burden in young broiler-cross chicks and to ...	2002	12033415
profile of salmonella enterica subsp. enterica (subspecies i) serotype 4,5,12:i:- strains causing food-borne infections in new york city.	strains of newly emerging salmonella enterica subsp. enterica (subspecies i) serotype 4,5,12:i:- causing food-borne infections, including a large food poisoning outbreak (n = 86) characterized by persistent diarrhea (14% bloody), abdominal pain, fever, and headache, were examined. the organisms were found in the stool samples from the patients. the biochemical profile of the organisms is consistent with that of s. enterica subsp. i serotypes, except for decreased dulcitol (13%) and increased ino ...	2002	12037044
molecular subtyping methods for detection of salmonella enterica serovar oranienburg outbreaks.	this study involved 82 salmonella enterica serovar oranienburg isolates from patients with gastroenteritis and/or focal infections, healthy carriers, and cuttlefish chips which were epidemiologically linked to a major outbreak that had affected 1,505 people in japan between 1998 and 1999. we concurrently investigated four different molecular subtyping methods using human salmonellosis-associated salmonella serovars and their applicability in detection of serovar oranienburg in an outbreak. pulse ...	2002	12037064
dna microarray-based typing of an atypical monophasic salmonella enterica serovar.	a multidrug-resistant fljb-lacking salmonella enterica serovar [4,5,12:i:-] emerged in spain in 1997. we analyzed the genome from four strains of this serovar using a microarray containing almost all the predicted protein coding regions of serovar typhimurium strain lt2, including the pslt plasmid. only a few differences from serovar typhimurium lt2 were observed, suggesting the serovar to be typhimurium as well. six regions of interest were identified from the microarray data. cluster i was a d ...	2002	12037067
detection of plasmid-mediated ampc beta-lactamase genes in clinical isolates by using multiplex pcr.	therapeutic options for infections caused by gram-negative organisms expressing plasmid-mediated ampc beta-lactamases are limited because these organisms are usually resistant to all the beta-lactam antibiotics, except for cefepime, cefpirome, and the carbapenems. these organisms are a major concern in nosocomial infections and should therefore be monitored in surveillance studies. six families of plasmid-mediated ampc beta-lactamases have been identified, but no phenotypic test can differentiat ...	2002	12037080
salmonella enterica serovar typhimurium and escherichia coli contamination of root and leaf vegetables grown in soils with incorporated bovine manure.	bovine manure, with or without added salmonella enterica serovar typhimurium (three strains), was incorporated into silty clay loam (scl) and loamy sand (ls) soil beds (53- by 114-cm surface area, 17.5 cm deep) and maintained in two controlled-environment chambers. the s. enterica serovar typhimurium inoculum was 4 to 5 log cfu/g in manure-fertilized soil. the conditions in the two environmental chambers, each containing inoculated and uninoculated beds of manure-fertilized soil, simulated daily ...	2002	12039728
differences in growth of salmonella enterica and escherichia coli o157:h7 on alfalfa sprouts.	sprout producers have recently been faced with several salmonella enterica and escherichia coli o157:h7 outbreaks. many of the outbreaks have been traced to sprout seeds contaminated with low levels of human pathogens. alfalfa seeds were inoculated with s. enterica and e. coli o157:h7 strains isolated from alfalfa seeds or other environmental sources and sprouted to examine growth of these human pathogens in association with sprouting seeds. s. enterica strains grew an average of 3.7 log(10) on ...	2002	12039774
unusual salmonella enterica serotype typhimurium isolate producing cmy-7, shv-9 and oxa-30 beta-lactamases.	beta-lactam resistance in salmonella isolates is increasing. this paper describes the combination of three different beta-lactamases, oxa-30, shv-9 and cmy-7, expressed by an isolate of salmonella enterica serotype typhimurium. this is the first report of an isolate of salmonella having both an extended-spectrum beta-lactamase and an ampc beta-lactamase.	2002	12039894
thermodynamics of aminoglycoside and acyl-coenzyme a binding to the salmonella enterica aac(6')-iy aminoglycoside n-acetyltransferase.	kinetic and mechanistic studies on the chromosomally encoded aminoglycoside 6'-n-acetyltransferase, aac(6')-iy, of salmonella enterica that confers resistance toward aminoglycosides have been previously reported [magnet et al. (2001) biochemistry 40, 3700-3709]. in the present study, equilibrium binding and the thermodynamic parameters of binding of aminoglycosides and acyl-coenzyme a derivatives to aac(6')-iy and of two mutants, c109a and the c109a/c70a double mutant, have been studied using fl ...	2002	12044186
enhanced antimicrobial effects of combination of lactate and diacetate on listeria monocytogenes and salmonella spp. in beef bologna.	the antimicrobial activities of salts of organic acids such as lactate and acetate are well documented, but there is limited information on their effect when used in combination. we previously reported enhanced inhibition of listeria monocvtogenes and salmonella enterica serovar enteritidis in sterile comminuted beef at 5 and 10 degrees c by combinations of sodium lactate (sl) (2.5%) and sodium diacetate (sda) (0.2%). the present study was undertaken to evaluate the inhibitory effect of these sa ...	2002	12051475
prevalence of escherichia coli o157:h7 prophage-like sequences among german salmonella enterica serotype typhimurium phage types and their use in detection of phage type dt104 by the polymerase chain reaction.	a 1.6kb dna fragment identified by random amplifiable polymorphic dna differentiation (rapd) from a salmonella enterica serotype typhimurium phage type dt104 isolate was used to investigate the prevalence of the region in 160 dt104 isolates, 83 other epidemiological important s. typhimurium phage types and 20 strains selected from 17 other salmonella serotypes. pcr screening tests using two different primer-sets derived from the rapd fragment's nucleotide sequence showed that 76% of the 160 dt10 ...	2002	12052335
effect of fermented feed on shedding of enterobacteriaceae by fattening pigs.	epidemiological studies showed that the use of fermented feed could significantly reduce salmonella prevalence in pigs compared to the use of normal feed. experimental challenge experiments with salmonella have however never been conducted to reveal the efficacy of fermented feed in reducing salmonella shedding and/or reducing the number of salmonella-positive pigs. a longitudinal study was conducted to measure the effect of fermented feed, in particular of its components lactic acid and lactoba ...	2002	12052336
monoclonal antibody of igg isotype against a cross-reactive lipopolysaccharide epitope of chlamydia and salmonella re chemotype enhances infectivity in l-929 fibroblast cells.	a murine monoclonal antibody (mab) 202d7 of igg3 isotype recognizes a lipopolysaccharide (lps) epitope of chlamydia spp. and cross-reacts with the re chemotype lps of salmonella and escherichia coli. the antibody exhibits strong complement activating properties and stimulates phagocytosis of salmonella enterica serovar minnesota re mutant by murine macrophages. salmonella re mutants are non-invasive for cell monolayers but still can enter and replicate in l-929 murine fibroblast cells. the entry ...	2002	12052561
antimicrobial resistance in salmonella isolated from animals and their environment in england and wales from 1988 to 1999.	resistance to 16 antimicrobial agents was monitored in 109,125 salmonella cultures isolated from animals, their environment and feedstuffs between 1988 and 1999. the sensitivity of the 6512 isolates of salmonella enterica enterica serotype dublin to all the antimicrobial agents tested varied from 98.2 per cent in 1997 to 99.7 per cent in 1990 and 1996. in contrast, among 28,053 isolates of salmonella enterica enterica serotype typhimurium, there was a marked decrease in their sensitivity to all ...	2002	12054133
early cytokine response of gnotobiotic piglets to salmonella enterica serotype typhimurium.	cytokine response against salmonella typhimurium is traditionally studied in conventional animals. germ-free animals, however, enable to study response against infection without background effect of other microorganisms. plasma and ileal inflammatory cytokines in germ-free piglets orally infected with virulent lt2 strain or, with a non-virulent sf1591 rough mutant were quantified by elisa. in plasma and ileal washes, ifn-gamma levels significantly increased in both infected groups. tnf-alpha and ...	2002	12056480
variation on a theme of sdr. dtdp-6-deoxy-l- lyxo-4-hexulose reductase (rmld) shows a new mg2+-dependent dimerization mode.	dtdp-6-deoxy-l-lyxo-4-hexulose reductase (rmld) catalyzes the final step in the conversion of dtdp-d-glucose to dtdp-l-rhamnose in an nad(p)h- and mg2+-dependent reaction. l-rhamnose biosynthesis is an antibacterial target. the structure of rmld from salmonella enterica serovar typhimurium has been determined, and complexes with nadh, nadph, and dtdp-l-rhamnose are reported. rmld differs from other short chain dehydrogenases in that it has a novel dimer interface that contains mg2+. enzyme catal ...	2002	12057193
pfs-dependent regulation of autoinducer 2 production in salmonella enterica serovar typhimurium.	bacterial intercellular communication provides a mechanism for signal-dependent regulation of gene expression to promote coordinated population behavior. salmonella enterica serovar typhimurium produces a non-homoserine lactone autoinducer in exponential phase as detected by a vibrio harveyi reporter assay for autoinducer 2 (ai-2) (m. g. surette and b. l. bassler, proc. natl. acad. sci. usa 95:7046-7050, 1998). the luxs gene product mediates the production of ai-2 (m. g. surette, m. b. miller, a ...	2002	12057938
differential regulation of multiple proteins of escherichia coli and salmonella enterica serovar typhimurium by the transcriptional regulator slya.	slya is a transcriptional regulator of escherichia coli, salmonella enterica, and other bacteria belonging to the enterobacteriaceae: the slya protein has been shown to be involved in the virulence of s. enterica serovar typhimurium, but its role in e. coli is unclear. in this study, we employed the proteome technology to analyze the slya regulons of enteroinvasive e. coli (eiec) and salmonella serovar typhimurium. in both cases, comparative analysis of the two-dimensional protein maps of a wild ...	2002	12057949
activation of prophage eib genes for immunoglobulin-binding proteins by genes from the ibrab genetic island of escherichia coli ecor-9.	four distinct escherichia coli immunoglobulin-binding (eib) genes, each of which encodes a surface-exposed protein that binds immunoglobulins in a nonimmune manner, are carried by separate prophages in e. coli reference (ecor) strain ecor-9. each eib gene was transferred to test e. coli strains, both in the form of multicopy recombinant plasmids and as lysogenized prophage. the derived lysogens express little or no eib protein, in sharp contrast to the parental lysogen, suggesting that ecor-9 ha ...	2002	12057959
characterization of salmonella enterica derivatives harboring defined aroc and salmonella pathogenicity island 2 type iii secretion system (ssav) mutations by immunization of healthy volunteers.	the attenuation and immunogenicity of two novel salmonella vaccine strains, salmonella enterica serovar typhi (ty2 delta aroc delta ssav, designated zh9) and s. enterica serovar typhimurium (tml delta aroc delta ssav, designated wt05), were evaluated after their oral administration to volunteers as single escalating doses of 10(7), 10(8), or 10(9) cfu. zh9 was well tolerated, not detected in blood, nor persistently excreted in stool. six of nine volunteers elicited anti-serovar typhi lipopolysac ...	2002	12065485
md-2, a novel accessory molecule, is involved in species-specific actions of salmonella lipid a.	salmonella lipid a is inactive in human macrophages despite being potently active in murine macrophages. we investigated the molecular basis for this species-specific action of salmonella lipid a. when murine cd14 (mcd14), mtlr4, and mmd-2 were all expressed in human monocytic thp-1 cells, these cells were capable of responding to salmonella lipid a. expressing each of these proteins separately did not impart such responsiveness. expression of mtlr4 plus mmd-2, but not mcd14 plus mtlr4 or mcd14 ...	2002	12065494
expression of the plasmodium falciparum immunodominant epitope (nanp)(4) on the surface of salmonella enterica using the autotransporter misl.	gram-negative bacterial proteins which are exported from the cytosol to the external environment by the type v secretion system are also known as autotransporters. once translocated to the periplasmic compartment by the sec-dependent general secretory pathway, their c-terminal domain forms a pore through which the n-terminal domain travels to the outer membrane without the need of other accessory proteins. misl (protein of membrane insertion and secretion) is a protein of unknown function locate ...	2002	12065502
the salmonella enterica serotype typhimurium effector proteins sipa, sopa, sopb, sopd, and sope2 act in concert to induce diarrhea in calves.	salmonella enterica serotype typhimurium requires a functional type iii secretion system encoded by salmonella pathogenicity island 1 (spi1) to cause diarrhea. we investigated the role of genes encoding secreted target proteins of the spi1-associated type iii secretion system for enteropathogenicity in calves. salmonella serotype typhimurium strains having mutations in sptp, avra, ssph1, or slrp induced fluid secretion in the bovine ligated ileal loop model at levels similar to that of the wild ...	2002	12065528
conjugal transfer of the virulence plasmid of salmonella enterica is regulated by the leucine-responsive regulatory protein and dna adenine methylation.	host-encoded functions that regulate the transfer operon (tra) in the virulence plasmid of salmonella enterica (pslt) were identified with a genetic screen. mutations that decreased tra operon expression mapped in the lrp gene, which encodes the leucine-responsive regulatory protein (lrp). reduced tra operon expression in an lrp- background is caused by lowered transcription of the traj gene, which encodes a transcriptional activator of the tra operon. gel retardation assays indicated that lrp b ...	2002	12067346
structural characterization of lipo-oligosaccharide (los) from yersinia pestis: regulation of los structure by the phopq system.	the two-component regulatory system phopq has been shown to regulate the expression of virulence factors in a number of bacterial species. for one such virulence factor, lipopolysaccharide (lps), the phopq system has been shown to regulate structural modifications in salmonella enterica var typhimurium. in yersinia pestis, which expresses lipo-oligosaccharide (los), a phopq regulatory system has been identified and an isogenic mutant constructed. to investigate potential modifications to los fro ...	2002	12067350
optimization of gfp levels for analyzing salmonella gene expression during an infection.	green fluorescent protein (gfp) is an attractive reporter for salmonella gene expression analysis but might interfere with virulence when expressed at high levels. to identify suitable gfp levels, we constructed a series of salmonella strains expressing different amounts of gfp and measured their fluorescence and colonization levels in infected mice. the results show that gfp concentrations in the range of 7000-200,000 molecules per salmonella cell are detectable in ex vivo samples using flow cy ...	2002	12067736
autoinduction of the ompr response regulator by acid shock and control of the salmonella enterica acid tolerance response.	salmonella enterica serovar typhimurium periodically experiences acid stress in a variety of host and non-host environments. an encounter with non-lethal acid stress (ph > 4) induces an assortment of physiological changes, called the acid tolerance response (atr), that helps the cell to tolerate extreme low ph (ph 3). these physiological changes differ in log phase and stationary phase cells and are controlled by different regulatory proteins. ompr is an acid-induced response regulator critical ...	2002	12068808