Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| a small protein that mediates the activation of a two-component system by another two-component system. | the pmra-pmrb two-component system of salmonella enterica controls resistance to the peptide antibiotic polymyxin b and to several antimicrobial proteins from human neutrophils. transcription of pmra-activated genes is induced by high iron, but can also be promoted by growth in low magnesium in a process that requires another two-component system, phop-phoq. here, we define the genetic basis for the interaction between the phop-phoq and pmra-pmrb systems. we have identified pmrd as a phop-activa ... | 2000 | 10775270 |
| salmonella typhimurium dt104 from livestock in japan. | we examined the distribution of multidrug-resistant salmonella enterica serotype typhimurium definitive phage type 104 (dt104) among japanese livestock from 1973 to 1998. the 144 s. typhimurium field isolates were tested for susceptibility to ampicillin, chloramphenicol, streptomycin, sulfamethoxazole, tetracycline, kanamycin, trimethoprim, nalidixic acid, and norfloxacin. thirty-six of 68 strains which exhibited resistance to five or more antimicrobials (acssut+) were identified as dt104. resul ... | 2000 | 10777852 |
| pcr typing of tetracycline resistance determinants (tet a-e) in salmonella enterica serotype hadar and in the microbial community of activated sludges from hospital and urban wastewater treatment facilities in belgium. | the distribution of tetracycline resistance determinants tet a-e was studied by pcr in 40 tetracycline-resistant salmonella enterica serotype hadar (s. hadar) isolates collected from human patients in 1996 and 1997, as well as in the microbial community originating from activated sludges of hospital and urban wastewater treatment facilities. a fast dna extraction and purification method from activated sludges was used to provide amplifiable dna. the method is based on the direct lysis of bacteri ... | 2000 | 10779622 |
| ceftriaxone-resistant salmonella infection acquired by a child from cattle. | the emergence of resistance to antimicrobial agents within the salmonellae is a worldwide problem that has been associated with the use of antibiotics in livestock. resistance to ceftriaxone and the fluoroquinolones, which are used to treat invasive salmonella infections, is rare in the united states. we analyzed the molecular characteristics of a ceftriaxone-resistant strain of salmonella enterica serotype typhimurium isolated from a 12-year-old boy with fever, abdominal pain, and diarrhea. | 2000 | 10781620 |
| identification of soxs-regulated genes in salmonella enterica serovar typhimurium. | salmonella enterica serovar typhimurium responds to superoxide-generating agents through soxr-mediated activation of the soxs gene, whose product, soxs, is necessary for resistance to oxidative stress. the s. enterica serovar typhimurium soxrs system also mediates redox-inducible resistance to diverse antibiotics, which may be relevant to clinical infections. in order to identify soxs-regulated genes in s. enterica serovar typhimurium, a laci-regulated expression system for the s. enterica serov ... | 2000 | 10613858 |
| proline catabolism by pseudomonas putida: cloning, characterization, and expression of the put genes in the presence of root exudates. | pseudomonas putida kt2442 is a root-colonizing strain which can use proline, one of the major components in root exudates, as its sole carbon and nitrogen source. a p. putida mutant unable to grow with proline as the sole carbon and nitrogen source was isolated after random mini-tn5-km mutagenesis. the mini-tn5 insertion was located at the puta gene, which is adjacent to and divergent from the putp gene. the puta gene codes for a protein of 1,315 amino acid residues which is homologous to the pu ... | 2000 | 10613867 |
| lesions in the nuo operon, encoding nadh dehydrogenase complex i, prevent purf-independent thiamine synthesis and reduce flux through the oxidative pentose phosphate pathway in salmonella enterica serovar typhimurium. | in salmonella enterica serovar typhimurium, purf-independent thiamine synthesis (or alternative pyrimidine biosynthesis) allows strains, under some growth conditions, to synthesize thiamine in the absence of the first step in the purine biosynthetic pathway. mutations have been isolated in a number of loci that prevent this synthesis and thus result in an apb(-) phenotype. here we identify a new class of mutations that prevent purf-independent thiamine synthesis and show that they are defective ... | 2000 | 10613887 |
| reduced flux through the purine biosynthetic pathway results in an increased requirement for coenzyme a in thiamine synthesis in salmonella enterica serovar typhimurium. | work presented here establishes a connection between cellular coenzyme a (coa) levels and thiamine biosynthesis in salmonella enterica serovar typhimurium. prior work showed that pane mutants (pane encodes ketopantoate reductase) had a conditional requirement for thiamine or pantothenate. data presented herein show that the nutritional requirement of pane mutants for either thiamine or pantothenate is manifest only when flux through the purine biosynthetic pathway is reduced. further, the data s ... | 2000 | 10613889 |
| molecular methods for the epidemiological typing of salmonella enterica serotype typhi from hong kong and vietnam. | a total of 217 and 73 strains of salmonella enterica serotype typhi isolated from 1985 to 1997 in hong kong and in 2 months of 1989 and 1990 in vietnam, respectively, were studied. these isolates were typed by plasmid profile analysis, plasmid fingerprinting, ribotyping with psti, and total dna fingerprinting with nari. there appeared to be no major outbreak of typhoid fever in hong kong during the study period since there was considerable heterogeneity among the isolates. isolates from hong kon ... | 2000 | 10618104 |
| evolutionary reversals during viral adaptation to alternating hosts. | experimental adaptation of the bacteriophage phix174 to a salmonella host depressed its ability to grow on the traditional escherichia host, whereas adaptation to escherichia did not appreciably affect growth on salmonella. continued host switching consistently exhibited this pattern. growth inhibition on escherichia resulted from two to three substitutions in the major capsid gene. when these phages were forced to grow again on escherichia, fitness recovery occurred predominantly by reversions ... | 2000 | 10628966 |
| the rfae gene from escherichia coli encodes a bifunctional protein involved in biosynthesis of the lipopolysaccharide core precursor adp-l-glycero-d-manno-heptose. | the intermediate steps in the biosynthesis of the adp-l-glycero-d-manno-heptose precursor of inner core lipopolysaccharide (lps) are not yet elucidated. we isolated a mini-tn10 insertion that confers a heptoseless lps phenotype in the chromosome of escherichia coli k-12. the mutation was in a gene homologous to the previously reported rfae gene from haemophilus influenzae. the e. coli rfae gene was cloned into an expression vector, and an in vitro transcription-translation experiment revealed a ... | 2000 | 10629197 |
| the amino terminus of salmonella enterica serovar typhimurium sigma(54) is required for interactions with an enhancer-binding protein and binding to fork junction dna. | transcription initiation by the sigma(54)-rna polymerase holoenzyme requires an enhancer-binding protein that is thought to contact sigma(54) to activate transcription. to identify potential enhancer-binding protein contact sites in sigma(54), we compared the abilities of wild-type and truncated forms of salmonella enterica serovar typhimurium sigma(54) to interact with the enhancer-binding protein dctd in a chemical cross-linking assay. removal of two regions in the amino-terminal portion of si ... | 2000 | 10629201 |
| opda, a salmonella enterica serovar typhimurium gene encoding a protease, is part of an operon regulated by heat shock. | the opda (prlc) gene of salmonella enterica serovar typhimurium and escherichia coli encodes the metalloprotease oligopeptidase a (opda). we report that opda is cotranscribed with a downstream open reading frame, yhiq. transcription of this operon is induced after a temperature shift (30 to 42 degrees c), and this induction depends on the heat shock sigma factor encoded by the rpoh (htpr) gene. | 2000 | 10629202 |
| expression and immunogenicity of hemagglutinin a from porphyromonas gingivalis in an avirulent salmonella enterica serovar typhimurium vaccine strain. | porphyromonas gingivalis is a major etiologic agent of periodontitis, a chronic inflammatory disease that ultimately results in the loss of the supporting tissues of the teeth. previous work has demonstrated the usefulness of avirulent salmonella enterica serovar typhimurium strains as antigen delivery systems for protective antigens of pathogens that colonize or cross mucosal surfaces. in this study, we constructed and characterized a recombinant s. enterica serovar typhimurium avirulent vaccin ... | 2000 | 10639440 |
| impact of heterogeneity within cultured cells on bacterial invasion: analysis of pseudomonas aeruginosa and salmonella enterica serovar typhi entry into mdck cells by using a green fluorescent protein-labelled cystic fibrosis transmembrane conductance regulator receptor. | the cystic fibrosis transmembrane conductance regulator (cftr) is a chloride ion channel that also serves as a receptor for entry of pseudomonas aeruginosa and salmonella enterica serovar typhi into epithelial cells. to evaluate heterogeneity in cftr protein expression in cultured cells and the effect of heterogeneity on internalization of different p. aeruginosa and serovar typhi strains, we used two-color flow cytometry and confocal laser microscopy to study bacterial uptake by madin-darby can ... | 2000 | 10639456 |
| use of lambda phage s and r gene products in an inducible lysis system for vibrio cholerae- and salmonella enterica serovar typhimurium-based dna vaccine delivery systems. | novel methods for adapting dna vaccine technology to the prevention of mucosal diseases are greatly needed. here we show that regulated expression of phage lambda lysis genes s and r causes dramatic lysis of both vibrio cholerae and salmonella enterica serovar typhimurium cells with concomitant release of plasmid dna into the surrounding media. we also used single and double dnase mutant strains to show that secreted v. cholerae dnases can adversely affect the integrity of dna molecules released ... | 2000 | 10639478 |
| the salmonella yopj-homologue avra does not possess yopj-like activity. | the yopj protein of yersinia pseudotuberculosis inhibits several eukaryotic signalling pathways that are normally activated in cells following their contact with bacteria. salmonella encodes a protein, avra, that is secreted by the typeiii inv/spa secretion system which is clearly homologous to yopj (56% identical, 87% similarity). since avra and yopjs similarity also encompassed a region of yopj that had previously been shown to be critical for its biological activity, we were interested whethe ... | 2000 | 10644492 |
| genetic and biochemical characterization of salmonella enterica serovar typhi deoxyribokinase. | we identified in the genome of salmonella enterica serovar typhi the gene encoding deoxyribokinase, deok. two other genes, vicinal to deok, were determined to encode the putative deoxyribose transporter (deop) and a repressor protein (deoq). this locus, located between the uhpa and ilvn genes, is absent in escherichia coli. the deok gene inserted on a plasmid provides a selectable marker in e. coli for growth on deoxyribose-containing medium. deoxyribokinase is a 306-amino-acid protein which exh ... | 2000 | 10648508 |
| prpr, ntra, and ihf functions are required for expression of the prpbcde operon, encoding enzymes that catabolize propionate in salmonella enterica serovar typhimurium lt2. | the genes required for the catabolism of propionate in salmonella enterica serovar typhimurium are organized as two transcriptional units (prpr and prpbcde) that are divergently transcribed from one another. sequence homology to genes encoding members of the sigma-54 family of transcriptional activators and the identification of a consensus sigma-54 promoter 5' to the prpbcde operon suggested that prpr was required to activate expression of this operon. we isolated insertions in prpr and showed ... | 2000 | 10648513 |
| insertional inactivation of genes encoding components of the sodium-type flagellar motor and switch of vibrio parahaemolyticus. | vibrio parahaemolyticus possesses two types of flagella, polar and lateral, powered by distinct energy sources, which are derived from the sodium and proton motive forces, respectively. although proton-powered flagella in escherichia coli and salmonella enterica serovar typhimurium have been extensively studied, the mechanism of torque generation is still not understood. molecular knowledge of the structure of the sodium-driven motor is only now being developed. in this work, we identify the swi ... | 2000 | 10648530 |
| genetically modified vibrio harveyi strains as potential bioindicators of mutagenic pollution of marine environments. | for biodetection of mutagenic pollution of marine environments, an organism naturally occurring in these habitats should be used. we found that marine bacterium vibrio harveyi may be an appropriate bioindicator of mutagenic pollution. for positive selection of mutants, we developed a simple method for isolation of v. harveyi mutants resistant to neomycin. we constructed genetically modified v. harveyi strains that produce significantly more neomycin-resistant mutants upon treatment with low conc ... | 2000 | 10653723 |
| molecular characterization of irish salmonella enterica serotype typhimurium: detection of class i integrons and assessment of genetic relationships by dna amplification fingerprinting. | salmonella enterica is among the principal etiological agents of food-borne illness in humans. increasing antimicrobial resistance in s. enterica is a cause for worldwide concern. there is concern at present in relation to the increasing incidence of human infection with antimicrobial agent-resistant strains of s. enterica serotype typhimurium, in particular of phage type dt104. integrons appear to play an important role in the dissemination of antimicrobial resistance genes in many enterobacter ... | 2000 | 10653725 |
| epidemic typhoid in vietnam: molecular typing of multiple-antibiotic-resistant salmonella enterica serotype typhi from four outbreaks. | multidrug-resistant salmonella enterica serotype typhi isolates from four outbreaks of typhoid fever in southern vietnam between 1993 and 1997 were compared. pulsed-field gel electrophoresis, bacteriophage and plasmid typing, and antibiotic susceptibilities showed that independent outbreaks of multidrug-resistant typhoid fever in southern vietnam are caused by single bacterial strains. however, different outbreaks do not derive from the clonal expansion of a single multidrug-resistant serotype t ... | 2000 | 10655411 |
| a role for salmonella fimbriae in intraperitoneal infections. | enteric bacteria possess multiple fimbriae, many of which play critical roles in attachment to epithelial cell surfaces. sef14 fimbriae are only found in salmonella enterica serovar enteritidis (s. enteritidis) and closely related serovars, suggesting that sef14 fimbriae may affect serovar-specific virulence traits. despite evidence that sef14 fimbriae are expressed by s. enteritidis in vivo, previous studies showed that sef14 fimbriae do not mediate adhesion to the intestinal epithelium. theref ... | 2000 | 10655518 |
| antimicrobial activity of home disinfectants and natural products against potential human pathogens. | to assess the efficacy of both natural products (vinegar, baking soda) and common commercial disinfectants (vesphene iise, tbq, clorox, lysol disinfectant spray, lysol antibacterial kitchen cleaner, mr. clean ultra, ethanol) designed for home or institutional use against potential human pathogens, including selected antibiotic-resistant bacteria. | 2000 | 10656352 |
| fragmentation of 23s rrna in strains of proteus and providencia results from intervening sequences in the rrn (rrna) genes. | intervening sequences (ivss) were originally identified in the rrl genes for 23s rrna (rrl genes, for large ribosomal subunit, part of rrn operon encoding rrna) of salmonella enterica serovars typhimurium lt2 and arizonae. these sequences are transcribed but later removed during rnase iii processing of the rrna, resulting in fragmentation of the 23s species; ivss are uncommon, but have been reported in at least 10 bacterial genera. through pcr amplification of ivs-containing regions of the rrl g ... | 2000 | 10648538 |
| igh-6(-/-) (b-cell-deficient) mice fail to mount solid acquired resistance to oral challenge with virulent salmonella enterica serovar typhimurium and show impaired th1 t-cell responses to salmonella antigens. | in the present study we evaluated the role of b cells in acquired immunity to salmonella infection by using gene-targeted b-cell-deficient innately susceptible mice on a c57bl/6 background (igh-6(-/-)). igh-6(-/-) mice immunized with a live, attenuated aroa salmonella enterica serovar typhimurium vaccine strain showed impaired long-term acquired resistance against the virulent serovar typhimurium strain c5. igh-6(-/-) mice were able to control a primary infection and to clear the inoculum from t ... | 2000 | 10603367 |
| in vivo characterization of the murine intranasal model for assessing the immunogenicity of attenuated salmonella enterica serovar typhi strains as live mucosal vaccines and as live vectors. | attenuated salmonella enterica serovar typhi live vector vaccine strains are highly immunogenic in mice following intranasal but not orogastric inoculation. to elucidate the relationship between organs within which vaccine organisms are found and the induction of specific serum immunoglobulin g (igg) antibodies, we examined the in vivo distribution of serovar typhi vaccine strain cvd 908-htra following intranasal administration. vaccine organisms were cultured from the nasal lymphoid tissue (nal ... | 2000 | 10603389 |
| epidemiology and characterization of animal salmonella enterica subspecies enterica serotype typhimurium dt104 in hungary. | reports on the internationally emerging significance of multiresistant zoonotic salmonella in animals and man prompted studies to estimate the significance of multiresistant salmonella enterica subspecies enterica serotype typhimurium (s. typhimurium) phage type dt104 of animal origin in hungary. a collection of 231 strains (primarily of goose, turkey, poultry and porcine origin from the years 1997-1998) was tested for resistance against 7 selected antibiotics (ampicillin, chloramphenicol, enrof ... | 2000 | 11402658 |
| antimicrobial drug resistance in non-typhoidal salmonellas from humans in england and wales in 1999: decrease in multiple resistance in salmonella enterica serotypes typhimurium, virchow, and hadar. | in 1999 the incidence of multiple drug resistance (to four or more antimicrobials) in non-typhoidal salmonellas from humans in england and wales fell in isolations of salmonella enterica serotypes typhimurium, virchow, and hadar. this fall has been most noticeable in s. typhimurium, where 59% of isolates were multiresistant compared to 81% in 1996. the main reason for this has been a 75% decline in isolations of multiply-resistant s. typhimurium definitive phage type (dt) 104 (mr dt104) since 19 ... | 2000 | 11272261 |
| the fliu and fliv genes are expressed as a single orf in salmonella choleraesuis. | a dna fragment carrying flagellar genes was cloned from salmonella choleraesuis. compared to the corresponding dna fragment of salmonella muenchen, this fragment contained three orfs instead of four shown in s. muenchen. the dna sequence data showed that there was an insertion of nucleotide c in the orf of the s. choleraesuis fliu gene, which resulted in the disappearance of a termination codon downstream. the recombinant plasmid pfu11 containing the coding region of the fliu gene made by pcr on ... | 2000 | 11142406 |
| high rate of resistance to nalidixic acid in salmonella enterica: its role as a marker of resistance to fluoroquinolones. | 2000 | 11168127 | |
| a cdna encoding 3-deoxy-d-manno-oct-2-ulosonate-8-phosphate synthase of pisum sativum l. (pea) functionally complements a kdsa mutant of the gram-negative bacterium salmonella enterica. | recombinant plasmids encoding 3-deoxy-d-manno-oct-2-ulosonate-8-phosphate (kdo-8-p) synthase (kdsa; ec 4.1.2.16) were identified from a cdna library of pisum sativum l. (pea) by complementing a temperature-sensitive kdsa(ts) mutant of the gram-negative bacterium salmonella enterica. sequence analysis of several inserts revealed a central open reading frame encoding a protein of 290 amino acids with a high degree of amino acid sequence similarity to bacterial kdsa. the cdna was confirmed by ampli ... | 2000 | 11219578 |
| multidrug-resistant strains of salmonella enterica serotype typhi are genetically homogenous and coexist with antibiotic-sensitive strains as distinct, independent clones. | the goal of this study was to report the molecular analysis of antibiotic-sensitive and multidrug-resistant (mdr) strains of salmonella typhi, using pulsed-field gel electrophoresis (pfge), with a particular emphasis on the coexistence of these strains in a typhoid-endemic region of karachi, pakistan. | 2000 | 11231181 |
| studies of the phenomenon of host adaptation in salmonella. | to study the phenomenon of host adaptation in salmonella, a mathematical model has been developed which permits a definition and experimental investigation of the specific interaction between the adapted serovar and the adequate host. after experimental infection using a mixture of equal parts of two salmonella strains, a and b, the bacterial concentrations ca and cb were determined in the organs of the animals infected. if an animal of species a and an animal of species b are infected with the ... | 2000 | 11244872 |
| salmonella derby cross-protection study. | an avirulent live (avl), salmonella choleraesuis vaccine (salmo shield live [grand laboratories, inc.]) was administered to pigs at weaning or 3 weeks of age. two weeks after vaccination the vaccinated pigs as well as unvaccinated control pigs were challenged intranasally with a commonly isolated environmental salmonella serotype, s. derby. at 2, 4, and 6 weeks after challenge, pigs were euthanized and cultured for s. derby. although the number of pigs in this study was too small to draw any def ... | 2000 | 19757566 |
| protection against experimental fowl typhoid by parenteral administration of live sl5828, an aroa-serc (aromatic dependent) mutant of a wild-type salmonella gallinarum strain made lysogenic for p22 sie. | a wild-type strain of salmonella enterica serotype gallinarum, lysogenized with p22 sie (superinfection-exclusion defective) was greatly attenuated for newly hatched or 21-day-old chickens. an aroa transductant of the lysogenic strain and an aroa-serc tetracycline-sensitive deletion or deletioninversion mutant of the latter were equally attenuated. intramuscular administration of the aroa-serc strain to 21-day-old chickens protected them against oral challenge with 10(6) colony forming units of ... | 2000 | 19184834 |
| evaluation of the effect of mannan-oligosaccharides on the competitive exclusion of salmonella enteritidis colonization in broiler chicks. | this study evaluated the protection against colonization by salmonella enterica serovar enteritidis in the chick's caecum when dosed with caecal contents from hens fed dietary carbohydrates based on mannose. protection was investigated by comparing the effects of four suspensions of hen caecal contents (hcc) fed diets supplemented with 2.5% d -mannose (man-hcc), 2.5% mannoseoligosaccharide (mos-hcc), 2.5% palm kernel meal (pkm-hcc) or unsupplemented mash (mashhcc). four trials to quantify and co ... | 2000 | 19184854 |
| pathogenicity of salmonella enteritidis phage types 4, 8 and 23 in specific pathogen free chicks. | the pathogenicity of two isolates of salmonella enterica serovar enteritidis (se) phage type (pt) 4, three of pt8 and one of pt23 was investigated in groups of 1-day-old specific pathogen free white leghorn chicks. two groups were crop gavaged with each culture but at two different doses. two additional groups were given salmonella enterica serovar pullorum (sp) at similar doses and one further group served as uninoculated controls. body weights were recorded at 14, 21, and 28 days postinoculati ... | 2000 | 19184855 |
| experimental salmonella enterica serovar pullorum infection in two commercial varieties of laying hens. | an experiment was carried out to investigate the biology of salmonella pullorum in two varieties of laying hens, from 5 days of age up to 9 months. one variety was resistant to systemic salmonellosis (light layers producing white eggs) and the other was considered susceptible (brown layers producing brown eggs). the brown birds were more affected by the infection, showing signs of clinical disease in the first month of life. later, these signs disappeared, but postmortem examination revealed per ... | 2001 | 19184886 |
| observations on the persistence and vertical transmission of salmonella enterica serovars pullorum and gallinarum in chickens: effect of bacterial and host genetic background. | commercial laying hens inoculated with a strain of salmonella enterica ser. pullorum when they were 4 days old showed no morbidity, but harboured infection until they came into lay, and then produced s. pullorum-contaminated eggs and infected progeny. there was limited evidence of transmission of maternal immunity to the progeny. attempts were made to set up similar infections in hens with salmonella gallinarum, but without success. infection either resulted in clinical disease or elimination of ... | 2001 | 19184904 |
| further studies on vertical transmission and persistence of salmonella enterica serovar enteritidis phage type 4 in chickens. | one-week-old commercial layers were infected orally with 10(8) colony forming units of salmonella enterica serovar enteritidis phage type 4. no mortality was observed. the inoculated organism was isolated in decreasing viable numbers from a number of tissues, particularly the spleen, liver and caeca. organisms present in the spleen were primarily localized within macrophages. no salmonella enteritidis organisms were isolated between 10 and 24 weeks of age, when the experiment was terminated afte ... | 2001 | 19184915 |
| chlortetracycline modulates acute phase response of ex vivo perfused pig livers, and inhibits tnf-alpha secretion by isolated kupffer cells. | tetracyclines have been shown to have anti-inflammatory effects in addition to their antimicrobial action. we investigated the effects of in vivo administration of chlortetracycline (ctc) on ex vivo perfused pig livers. the retention and clearance of salmonella choleraesuis, production of acute phase proteins c-reactive protein (crp), and haptoglobin (hpg) by whole livers were studied. the in vitro modulation by ctc of tnf-alpha secretion by pig kupffer cells (kc) was also studied. pigs were dos ... | 2001 | 11247048 |
| thermal inactivation of stationary-phase and acid-adapted escherichia coli o157:h7, salmonella, and listeria monocytogenes in fruit juices. | the heat resistance of stationary-phase and acid-adapted escherichia coli o157:h7, salmonella enterica (serotypes typhimurium, enteritidis, gaminara, rubislaw, and hartford), and listeria monocytogenes was evaluated in single-strength apple. orange, and white grape juices adjusted to ph 3.9. the heat resistance increased significantly (p < 0.05) after acid adaptation. salmonella had an overall lower heat resistance than the other pathogens. acid-adapted e. coli o157:h7 presented the highest heat ... | 2001 | 11252473 |
| induction of protective immunity against streptococcus mutans colonization after mucosal immunization with attenuated salmonella enterica serovar typhimurium expressing an s. mutans adhesin under the control of in vivo-inducible nirb promoter. | the purpose of the present study was to evaluate the effectiveness of an attenuated salmonella enterica serovar typhimurium vaccine strain expressing the saliva-binding region (sbr) of the streptococcus mutans antigen i/ii adhesin, either alone or linked with the mucosal adjuvant cholera toxin a2 and b subunits (cta2/b) and under the control of the anaerobically inducible nirb promoter, in inducing a protective immune response against s. mutans infection. balb/c mice were immunized by either the ... | 2001 | 11254570 |
| salmonella enterica serovar typhimurium induces cell death in bovine monocyte-derived macrophages by early sipb-dependent and delayed sipb-independent mechanisms. | it was previously demonstrated that salmonella enterica serovar typhimurium induces cell death with features of apoptosis in murine macrophages. mice infected with salmonella serovar typhimurium develop systemic disease without diarrhea, whereas the infection in cattle and in humans is localized and characterized by diarrhea. considering these clinical disease expression differences between mice and cattle, we investigated whether serovar typhimurium is cytotoxic for bovine macrophages. macropha ... | 2001 | 11254586 |
| complete dna sequence and comparative analysis of the 50-kilobase virulence plasmid of salmonella enterica serovar choleraesuis. | the complete nucleotide sequence of pkdsc50, a large virulence plasmid from salmonella enterica serovar choleraesuis strain rf-1, has been determined. we identified 48 of the open reading frames (orfs) encoded by the 49,503-bp molecule. pkdsc50 encodes a known virulence-associated operon, the spv operon, which is composed of genes essential for systemic infection by nontyphoidal salmonella. analysis of the genetic organization of pkdsc50 suggests that the plasmid is composed of several virulence ... | 2001 | 11254626 |
| curli fibers mediate internalization of escherichia coli by eukaryotic cells. | curli fibers are adhesive surface fibers expressed by escherichia coli and salmonella enterica that bind several host extracellular matrix and contact phase proteins and were assumed to have a role in pathogenesis. the results presented here suggest that one such role is internalization into host cells. an e. coli k-12 strain transformed with a low-copy vector containing the gene cluster encoding curli fibers (csg operon) was internalized by several lines of eukaryotic cells. the internalization ... | 2001 | 11254632 |
| multidrug resistance is mediated by large plasmids carrying a class 1 integron in the emergent salmonella enterica serotype [4,5,12:i:-]. | a multidrug-resistant salmonella enterica serotype [4,5,12:i:-] clone carried a class 1 integron harboring dfra12 and aada2 gene cassettes and bla(tem-1), aac(3)-iv, cmla1, and teta genes located in large plasmids of about 140 kb (carrying spv) or 120 kb (lacking spv). several segregants, lacking multidrug resistance, contained a plasmid smaller than the parental one and no longer hybridized with probes for the lost resistances. the genes mediating resistance to ampicillin, chloramphenicol, and ... | 2001 | 11257054 |
| restricted growth of ent(-) and tonb mutants of salmonella enterica serovar typhi in human mono mac 6 monocytic cells. | monocytes and macrophages are an important host defense in humans infected with salmonella enterica serovar typhi. bacterial ability to survive in these cells is therefore a crucial virulence characteristic of this pathogen. in this study, we demonstrate that growth of a salmonella enterica serovar typhi enterochelin synthesis mutant and a tonb mutant in the human monocyte cell line mono mac 6 is restricted compared to that of the parental wild-type ty2 strain. these results suggest that enteroc ... | 2001 | 11257540 |
| the salmonella spvb virulence gene encodes an enzyme that adp-ribosylates actin and destabilizes the cytoskeleton of eukaryotic cells. | adp-ribosylating enzymes, such as cholera and diphtheria toxins, are key virulence factors for a variety of extracellular bacterial pathogens but have not been implicated previously during intracellular pathogenesis. salmonella strains are capable of invading epithelial cells and localizing in macrophages during infection. the spvb virulence gene of salmonella is required for human macrophage cytotoxicity in vitro and for enhancing intracellular bacterial proliferation during infection. here, we ... | 2001 | 11260464 |
| identification of a non-haem catalase in salmonella and its regulation by rpos (sigmas). | we report the identification and functional analysis of katn, a gene encoding a non-haem catalase of salmonella enterica serotype typhimurium. katn, which is not present in escherichia coli, is located between the ycigfe and ycid e. coli homologues in the salmonella genome. its predicted protein product has a molecular weight of 31 826 da and is similar to the mn-catalases of lactobacillus plantarum and thermus spp. its product, katn, was visualized as a 37 kda protein in e. coli maxicells. a ka ... | 2001 | 11260470 |
| evolutionary adaptation to temperature. viii. effects of temperature on growth rate in natural isolates of escherichia coli and salmonella enterica from different thermal environments. | are enteric bacteria specifically adapted to the thermal environment of their hosts? in particular, do the optimal temperatures and thermal niches of the bacterial flora reflect seasonal, geographic, or phylogenetic differences in their hosts' temperatures? we examined these questions by measuring the relationship between the temperature-dependent growth rates of enteric bacteria in a free-living ectothermic host. we sampled two species of enteric bacteria (escherichia coli and salmonella enteri ... | 2001 | 11263744 |
| enhancement of translation by the epsilon element is independent of the sequence of the 460 region of 16s rrna. | the epsilon enhancer element is a pyrimidine-rich sequence that increases expression of t7 gene 10 and a number of escherichia coli mrnas during initiation of translation and inhibits expression of the recf mrna during elongation. based on its complementarity to the 460 region of 16s rrna, it has been proposed that epsilon exerts its enhancer activity by base pairing to this complementary rrna sequence. we have tested this model of enhancer action by constructing mutations in the 460 region of 1 ... | 2001 | 11266541 |
| virulent strains of salmonella enteritidis disrupt the epithelial barrier of caco-2 and hep-2 cells. | to confirm the existence in nature of salmonella enteritidis strains of different degrees of virulence and to elucidate the mechanisms underlying the effects of such strains on the epithelial barrier function, the consequences of infection of caco-2 cells and hep-2 cells with 15 s. enteritidis strains in a chicken infection model were examined. the more virulent strains of s. enteritidis, which are biofilm producers in adherence test medium, were able to disrupt hep-2 and caco-2 monolayers, as s ... | 2001 | 11271420 |
| the spread and antibiotic resistance of salmonella enterica serotype typhimurium dt104 in hungary. | comparison of phage types (pts) determined by felix and callow's and anderson's methods was performed testing 99 human strains of s. enterica serotype typhimurium (s. typhimurium) isolated in hungary. pt2 and pt2c--according to felix-callow--corresponded with anderson's dt104 in case of 39 strains out of 40. among 59 isolates belonging to other felix-callow's pts only one strain was found which was dt 104. similar unambiguous equalities could not be established between any other pts comparing th ... | 2001 | 11233703 |
| typhoid fever and genetic polymorphisms at the natural resistance-associated macrophage protein 1. | control of salmonella enterica serovar typhimurium (s. typhimurium) infection in the mouse model of typhoid fever is critically dependent on the natural resistance-associated macrophage protein 1 (nramp1). in this study, we examined the role of genetic polymorphisms in the human homologue, nramp1, in resistance to typhoid fever in southern vietnam. patients with blood-culture-confirmed typhoid fever and healthy control subjects were genotyped for 6 polymorphic markers within and near nramp1 on c ... | 2001 | 11237848 |
| molecular evolution of the gdp-mannose pathway genes (manb and manc) in salmonella enterica. | the evolutionary history of the gdp-mannose pathway in salmonella enterica was studied via sequencing manb and manc genes from 13 representative strains for o antigens containing mannose and/or sugar derivatives of gdp-d-mannose. in addition, colanic acid (ca) manb and manc genes were sequenced from selected strains, as the basis for a detailed comparison. interestingly, including the eight previously characterized o antigen gene clusters, 12 of the 21 s. enterica strains studied in total (each ... | 2001 | 11238967 |
| the crystal structure of dtdp-d-glucose 4,6-dehydratase (rmlb) from salmonella enterica serovar typhimurium, the second enzyme in the dtdp-l-rhamnose pathway. | l-rhamnose is a 6-deoxyhexose that is found in a variety of different glycoconjugates in the cell walls of pathogenic bacteria. the precursor of l-rhamnose is dtdp-l-rhamnose, which is synthesised from glucose- 1-phosphate and deoxythymidine triphosphate (dttp) via a pathway requiring four enzymes. significantly this pathway does not exist in humans and all four enzymes therefore represent potential therapeutic targets. dtdp-d-glucose 4,6-dehydratase (rmlb; ec 4.2.1.46) is the second enzyme in t ... | 2001 | 11243820 |
| global analysis of escherichia coli gene expression during the acetate-induced acid tolerance response. | the ability of escherichia coli to survive at low ph is strongly affected by environmental factors, such as composition of the growth medium and growth phase. exposure to short-chain fatty acids, such as acetate, proprionate, and butyrate, at neutral or nearly neutral ph has also been shown to increase acid survival of e. coli and salmonella enterica serovar typhimurium. to investigate the basis for acetate-induced acid tolerance in e. coli o157:h7, genes whose expression was altered by exposure ... | 2001 | 11244055 |
| altered pathway routing in a class of salmonella enterica serovar typhimurium mutants defective in aminoimidazole ribonucleotide synthetase. | in salmonella enterica serovar typhimurium, purine nucleotides and thiamine are synthesized by a branched pathway. the last known common intermediate, aminoimidazole ribonucleotide (air), is formed from formylglycinamidine ribonucleotide (fgam) and atp by air synthetase, encoded by the puri gene in s. enterica. reduced flux through the first five steps of de novo purine synthesis results in a requirement for purines but not necessarily thiamine. to examine the relationship between the purine and ... | 2001 | 11244062 |
| sira orthologs affect both motility and virulence. | the sira gene of salmonella enterica serovar typhimurium encodes a two-component response regulator of the fixj family that has a positive regulatory influence on the expression of type iii secretion genes involved with epithelial cell invasion and the elicitation of bovine gastroenteritis. sira orthologs in pseudomonas, vibrio, and erwinia control the expression of distinct virulence genes in these genera, but an evolutionarily conserved target of sira regulation has never been identified. in t ... | 2001 | 11244064 |
| salmonella host cell invasion emerged by acquisition of a mosaic of separate genetic elements, including salmonella pathogenicity island 1 (spi1), spi5, and sope2. | salmonella spp. possess a conserved type iii secretion system encoded within the pathogenicity island 1 (spi1; centisome 63), which mediates translocation of effector proteins into the host cell cytosol to trigger responses such as bacterial internalization. several translocated effector proteins are encoded in other regions of the salmonella chromosome. it remains unclear how this complex chromosomal arrangement of genes for the type iii apparatus and the effector proteins emerged and how the d ... | 2001 | 11244077 |
| the interaction of protein structure, selection, and recombination on the evolution of the type-1 fimbrial major subunit (fima) from escherichia coli. | fimbrial adhesins allow bacteria to interact with and attach to their environment. the bacteria possibly benefit from these interactions, but all external structures including adhesins also allow bacteria to be identified by other organisms. thus adhesion molecules might be under multiple forms of selection including selection to constrain functional interactions or evolve novel epitopes to avoid recognition. we address these issues by studying genetic diversity in the escherichia coli type-1 fi ... | 2001 | 11244580 |
| epithelial cell contact-induced alterations in salmonella enterica serovar typhi lipopolysaccharide are critical for bacterial internalization. | the invasion of pseudomonas aeruginosa and salmonella enterica serovar typhi into epithelial cells depends on the cystic fibrosis transmembrane conductance regulator (cftr) protein as an epithelial receptor. in the case of p. aeruginosa, the bacterial ligand for cftr is the outer core oligosaccharide portion of the lipopolysaccharide (lps). to determine whether serovar typhi lps is also a bacterial ligand mediating internalization, we used both p. aeruginosa and serovar typhi lps as a competitiv ... | 2001 | 11696036 |
| a minor capsid protein p30 is essential for bacteriophage prd1 capsid assembly. | bacteriophage prd1 is a double-stranded dna virus infecting gram-negative hosts. it has a membrane component located in the interior of the isometric capsid. in addition to the major capsid protein p3, the capsid contains a 9 kda protein p30. protein p30 is proposed to be located between the adjacent facets of the icosahedral capsid and is required for stable capsid assembly. in its absence, an empty phage-specific membrane vesicle is formed. the major protein component of this vesicle is a phag ... | 2001 | 11697904 |
| is186 insertion at a hot spot in the lon promoter as a basis for lon protease deficiency of escherichia coli b: identification of a consensus target sequence for is186 transposition. | the radiation sensitivity of escherichia coli b was first described more than 50 years ago, and the genetic locus responsible for the trait was subsequently identified as lon (encoding lon protease). we now show that both e. coli b and the first reported e. coli k-12 lon mutant, ab1899, carry is186 insertions in opposite orientations at a single site in the lon promoter region and that this site represents a natural hot spot for transposition of the insertion sequence (is) element. our analysis ... | 2001 | 11698384 |
| papb paralogues and their effect on the phase variation of type 1 fimbriae in escherichia coli. | recent work has demonstrated that expression of type 1 fimbriae is repressed by papb, a regulator of pyelonephritis-associated pili (p-pili). papb belongs to family of related adhesin regulators, for which consensus residues required for dna binding and oligomerization have been identified. of the regulators tested in this study, papb, sfab (s-fimbriae) and pefb (salmonella enterica serovar typhimurium--plasmid-encoded fimbriae) repressed fimb-promoted off-to-on inversion of the fim switch, alth ... | 2001 | 11703657 |
| in vivo genetic analysis indicates that phop-phoq and the salmonella pathogenicity island 2 type iii secretion system contribute independently to salmonella enterica serovar typhimurium virulence. | many virulence factors are required for salmonella enterica serovar typhimurium to replicate intracellularly and proliferate systemically within mice. in this work, we have carried out genetic analyses in vivo to determine the functional relationship between two major virulence factors necessary for systemic infection by s. enterica serovar typhimurium: the salmonella pathogenicity island 2 (spi-2) type iii secretion system (ttss) and the phop-phoq two-component regulatory system. although previ ... | 2001 | 11705895 |
| novel salmonella enterica serovar typhimurium protein that is indispensable for virulence and intracellular replication. | upon contact with host cells, the intracellular pathogen salmonella enterica serovar typhimurium promotes its uptake, targeting, and survival in intracellular niches. in this process, the bacterium evades the microbicidal effector mechanisms of the macrophage, including oxygen intermediates. this study reports the phenotypic and genotypic characterization of an s. enterica serovar typhimurium mutant that is hypersusceptible to superoxide. the susceptible phenotype is due to a mudj insertion-inac ... | 2001 | 11705915 |
| regulated antigen expression in live recombinant salmonella enterica serovar typhimurium strongly affects colonization capabilities and specific cd4(+)-t-cell responses. | regulated antigen expression can influence the immunogenicity of live recombinant salmonella vaccines, but a rational optimization has remained difficult since important aspects of this effect are incompletely understood. here, attenuated salmonella enterica serovar typhimurium sl3261 strains expressing the model antigen gfp_ova were used to quantify in vivo antigen levels by flow cytometry and to simultaneously follow the crucial early steps of antigen-specific t-cell responses in mice that are ... | 2001 | 11705925 |
| salmonella enterica serovar pullorum persists in splenic macrophages and in the reproductive tract during persistent, disease-free carriage in chickens. | salmonella enterica serovar pullorum is worldwide a poultry pathogen of considerable economic importance, particularly in those countries with a developing poultry industry. in addition to the characteristic high mortality rates among young chicks, one of the features of salmonella serovar pullorum infection is that it persists for long periods in convalescent chicks in the absence of clinical disease. this can lead to colonization of the reproductive tract of chickens and at sexual maturity can ... | 2001 | 11705970 |
| infection of synovial fibroblasts in culture by yersinia enterocolitica and salmonella enterica serovar enteritidis: ultrastructural investigation with respect to the pathogenesis of reactive arthritis. | synovial fibroblasts were infected with yersinia enterocolitica or salmonella enterica serovar enteritidis and analyzed by electron microscopy and fluorescence in situ hybridization. intracellular bacterial replication was followed by degradation leading to "ghosts" possessing lipopolysaccharides but not dna. however, single bacteria survived for more than 2 weeks. therefore, transient intra-articular infection might be the missing link between initial intestinal infection and late synovial infl ... | 2001 | 11705977 |
| salmonella dna adenine methylase mutants elicit protective immune responses to homologous and heterologous serovars in chickens. | salmonella dna adenine methylase (dam) mutants that lack or overproduce dam are highly attenuated for virulence in mice and confer protection against murine typhoid fever. to determine whether vaccines based on dam are efficacious in poultry, a salmonella dam(-) vaccine was evaluated in the protection of chicken broilers against oral challenge with homologous and heterologous salmonella serovars. a salmonella enterica serovar typhimurium dam(-) vaccine strain was attenuated for virulence in day- ... | 2001 | 11705984 |
| the ppp-family protein phosphatases prpa and prpb of salmonella enterica serovar typhimurium possess distinct biochemical properties. | salmonella enterica serovar typhimurium requires mn(2+), but only a few mn(2+)-dependent enzymes have been identified from bacteria. to characterize mn(2+)-dependent enzymes from serovar typhimurium, two putative ppp-family protein phosphatase genes were cloned from serovar typhimurium and named prpa and prpb. their dna-derived amino acid sequences showed 61% identity to the corresponding escherichia coli proteins and 41% identity to each other. each phosphatase was expressed in e. coli and puri ... | 2001 | 11717262 |
| increase in salmonella enterica subspecies diarizonae serovar 61:k:1,5,(7) in sheep. | 2001 | 11720209 | |
| cellular location and temperature-dependent assembly of inchi1 plasmid r27-encoded trhc-associated conjugative transfer protein complexes. | conjugal transfer of inchi plasmid dna between gram-negative bacteria is temperature sensitive, as mating is optimal between 22 degrees c and 30 degrees c but is inhibited at 37 degrees c. r27, isolated from salmonella enterica serovar typhi, is an inchi1 plasmid of 180 kbp that has been sequenced completely. the gene encoding green fluorescent protein (gfp) was inserted into r27 in frame with trhc. trhc is a mating pair formation (mpf) protein that is essential for plasmid transfer and h-pilus ... | 2001 | 11722736 |
| delivering dangerous cargoes. | 2001 | 11723464 | |
| evaluation of universal preenrichment broth for growth of heat-injured pathogens. | universal preenrichment broth (upb) was developed to enable enrichment of injured foodborne pathogens of different genera simultaneously in lieu of having to undergo separate simultaneous enrichment cultures for subsequent detection or isolation of each pathogen. enrichment conditions in upb for growth of injured pathogens to populations that will enable pathogen detection by rapid immuno-based or polymerase chain reaction (pcr)-based assays have not been defined. hence, studies were done to det ... | 2001 | 11726154 |
| prevalence of salmonella serovars in chickens in turkey. | in this study, 151 (18.6%) of 814 ceca obtained during in-line processing of 28 broiler (hybro g, avian, arbor acres, and cobb breeds) and 5 layer (ross, tetra sl, isa brown, and brown nick breeds) flocks in turkey were found to be contaminated with four different salmonella serovars. only salmonella enterica subsp. enterica serovar enteritidis (salmonella enteritidis) was recovered from layer birds, whereas salmonella enteritidis (81.5%). salmonella agona (7.6%), salmonella thompson (10.1%), an ... | 2001 | 11726169 |
| three molecular methods to identify salmonella enterica serotype typhimurium dt104: pcr fingerprinting, multiplex pcr and rapid pfge. | here we report the accuracy with which three molecular techniques (pcr fingerprinting, multiplex pcr and macrorestriction profiling) distinguished salmonella enterica typhimurium dt104 (hereafter referred to as dt104) from other related strains of salmonella. each technique was tested by screening a set of 20 isolates (10 dt104, eight non-dt104 typhimurium, one s. enterica agona, one s. enterica newport) and each consistently differentiated dt104 from non-dt104 isolates based on visual inspectio ... | 2001 | 11728711 |
| contribution of flagella and invasion proteins to pathogenesis of salmonella enterica serovar enteritidis in chicks. | to explore the relative contribution that flagella and salmonella invasion proteins make to the virulence of salmonella enteritidis in poultry, 20-day-old chicks were challenged orally and by subcutaneous injection with wild-type strain se-hcd, two non-flagellated mutants (flic::tn10 mutant and flhd::tn10 mutant) and two salmonella invasion protein insertion mutants (sipd and iacp). when injected subcutaneously, wild-type se-hcd was the only strain to cause substantial mortality and morbidity an ... | 2001 | 11731137 |
| molecular characterization of global regulatory rna species that control pathogenicity factors in erwinia amylovora and erwinia herbicola pv. gypsophilae. | rsmb(ecc) specifies a nontranslatable rna regulator that controls exoprotein production and pathogenicity in soft rot-causing erwinia carotovora subsp. carotovora. this effect of rsmb(ecc) rna is mediated mostly by neutralizing the function of rsma(ecc), an rna-binding protein of e. carotovora subsp. carotovora, which acts as a global negative regulator. to determine the occurrence of functional homologs of rsmb(ecc) in non-soft-rot-causing erwinia species, we cloned the rsmb genes of e. amylovo ... | 2001 | 11222584 |
| multiple antibiotic resistance (mar) locus in salmonella enterica serovar typhimurium dt104. | in order to understand the role of the mar locus in salmonella with regard to multiple antibiotic resistance, cyclohexane resistance, and outer membrane protein f (ompf) regulation, a mara::gfp reporter mutant was constructed in an antibiotic-sensitive salmonella enterica serovar typhimurium dt104 background. salicylate induced mara, whereas a number of antibiotics, disinfectants, and various growth conditions did not. increased antibiotic resistance was observed upon salicylate induction, altho ... | 2001 | 11229910 |
| biological sensor for sucrose availability: relative sensitivities of various reporter genes. | a set of three sucrose-regulated transcriptional fusions was constructed. fusions p61rytir, p61rylac, and p61ryice contain the scrr sucrose repressor gene and the promoterless gfp, lacz, and inaz reporter genes, respectively, fused to the scry promoter from salmonella enterica serovar typhimurium. cells of erwinia herbicola containing these fusions are induced only in media amended with sucrose, fructose, or sorbose. while a large variation in sucrose-dependent reporter gene activity was observe ... | 2001 | 11229926 |
| serology of typhoid fever in an area of endemicity and its relevance to diagnosis. | currently, the laboratory diagnosis of typhoid fever is dependent upon either the isolation of salmonella enterica subsp. enterica serotype typhi from a clinical sample or the detection of raised titers of agglutinating serum antibodies against the lipopolysaccharide (lps) (o) or flagellum (h) antigens of serotype typhi (the widal test). in this study, the serum antibody responses to the lps and flagellum antigens of serotype typhi were investigated with individuals from a region of vietnam in w ... | 2001 | 11230418 |
| molecular typing and epidemiological study of salmonella enterica serotype typhimurium isolates from cattle by fluorescent amplified-fragment length polymorphism fingerprinting and pulsed-field gel electrophoresis. | one hundred twenty salmonella enterica serotype typhimurium strains, including 103 isolates from cattle gathered between 1977 and 1999 in the prefecture located on the northern-most island of japan, were analyzed by using fluorescent amplified-fragment length polymorphism (faflp) and pulsed-field gel electrophoresis (pfge) to examine the genotypic basis of the epidemic. among these strains, there were 17 faflp profiles that formed four distinct clusters (a, b, c, and d). isolates that belonged t ... | 2001 | 11230427 |
| isolation and characterization of a salmonella enterica serotype typhi variant and its clinical and public health implications. | we report the isolation and characterization of a member of the family enterobacteriaceae isolated from the gallbladder pus of a food handler. conventional biochemical tests suggested salmonella enterica serotype typhi, but the isolate agglutinated with poly(o), 2o, 9o, and vi salmonella antisera but not with poly(h) or any individual h salmonella antisera. 16s rrna gene sequencing showed that there were two base differences between the isolate and salmonella enterica serotype montevideo, four b ... | 2001 | 11230457 |
| evaluation of the components of a commercial probiotic in gnotobiotic mice experimentally challenged with salmonella enterica subsp. enterica ser. typhimurium. | vitacanis((r)), a probiotic preparation containing a lactobacillus acidophilus, an enterococcus faecium and a saccharomyces cerevisiae, has been developed for the prevention of intestinal disorders in dogs and cats. in the present study, these microorganisms were tested jointly or singly during experimental infection of gnotobiotic mice with salmonella typhimurium. four experimental groups consisting of animals given probiotics jointly or singly and a control group consisting of germfree mice we ... | 2001 | 11230939 |
| actin is adp-ribosylated by the salmonella enterica virulence-associated protein spvb. | the salmonella enterica virulence-associated protein spvb was recently shown to contain a carboxy-terminal mono(adp-ribosyl)transferase domain. we demonstrate here that the catalytic domain of spvb as well bacterial extracts containing full-length spvb modifies a 43 kda protein from macrophage-like j774-a.1 and epithelial mdck cells as shown by label transfer from [32p]-nicotinamide adenine dinucleotide (nad) to the 43 kda protein. when analysed by two-dimensional gel electrophoresis, the same p ... | 2001 | 11169102 |
| the insect endosymbiont sodalis glossinidius utilizes a type iii secretion system for cell invasion. | sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, glossina spp. in this study, we have used tn5 mutagenesis and a negative selection procedure to derive a s. glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse. this mutant strain harbors tn5 integrated into a chromosomal gene sharing high sequence identity with a type iii secretion system invasion ... | 2001 | 11172045 |
| use of molecular subtyping in surveillance for salmonella enterica serotype typhimurium. | because salmonella enterica serotype typhimurium is the most common serotype isolated from persons with salmonellosis in the united states, it is difficult to detect unusual clusters or outbreaks. to determine whether molecular subtyping could be useful in public health surveillance for s. enterica serotype typhimurium, the minnesota department of health initiated the routine use of pulsed-field gel electrophoresis (pfge) of isolates. | 2001 | 11172141 |
| molecular characterization of streptococcus pneumoniae type 4, 6b, 8, and 18c capsular polysaccharide gene clusters. | capsular polysaccharide (cps) is a major virulence factor in streptococcus pneumoniae. cps gene clusters of s. pneumoniae types 4, 6b, 8, and 18c were sequenced and compared with those of cps types 1, 2, 14, 19f, 19a, 23f, and 33f. all have the same four genes at the 5' end, encoding proteins thought to be involved in regulation and export. sequences of these genes can be divided into two classes, and evidence of recombination between them was observed. next is the gene encoding the transferase ... | 2001 | 11179285 |
| staphylococcus aureus and salmonella enterica serovar dublin induce tumor necrosis factor-related apoptosis-inducing ligand expression by normal mouse and human osteoblasts. | staphylococcus aureus and salmonella enterica serovar dublin invade osteoblasts and are causative agents of human bone disease. in the present study, we examined the ability of s. aureus and salmonella serovar dublin to induce the production of tumor necrosis factor-related apoptosis-inducing ligand (trail) by normal osteoblasts. normal mouse and human osteoblasts were cocultured with s. aureus or salmonella serovar dublin at different multiplicities of infection. following initial incubation an ... | 2001 | 11179330 |
| rat mannose-binding protein a binds cd14. | lipopolysaccharide (lps) has been known to induce inflammation by interacting with cd14, which serves as a receptor for lps. mannose-binding protein (mbp) belongs to the collectin subgroup of the c-type lectin superfamily, along with surfactant proteins sp-a and sp-d. we have recently demonstrated that sp-a modulates lps-induced cellular responses by interaction with cd14 (h. sano, h. sohma, t. muta, s. nomura, d. r. voelker, and y. kuroki, j. immunol. 163:387-395, 2000) and that sp-d also inter ... | 2001 | 11179331 |
| adoptive transfer of cd4+ t cells specific for subunit a of helicobacter pylori urease reduces h. pylori stomach colonization in mice in the absence of interleukin-4 (il-4)/il-13 receptor signaling. | protection in the murine model of helicobacter pylori infection may be mediated by cd4+ t cells, but the mechanism remains unclear. to better understand how protection occurs in this model, we generated and characterized h. pylori urease-specific cd4+ t cells from balb/c mice immunized with salmonella enterica serovar typhimurium expressing h. pylori urease (subunits a and b). the cd4+ t cells were found to be specific for subunit a (urea). upon antigen-specific stimulation, expression of interl ... | 2001 | 11179348 |
| antibiotic susceptibilities of salmonella enterica serovar typhi and s. enterica serovar paratyphi a isolated from patients in japan. | the antibiotic susceptibilities of 62 strains of salmonella enterica serovar typhi and 37 strains of s. enterica serovar paratyphi a were investigated with 18 antibiotics. eighteen s. enterica serovar typhi isolates and five s. enterica serovar paratyphi a isolates were resistant to one or more antimicrobial agents, among which 10 s. enterica serovar typhi isolates were nalidixic acid resistant and also showed decreased ciprofloxacin susceptibility. | 2001 | 11181390 |
| new insights into endotoxin-induced activation of macrophages: involvement of a k+ channel in transmembrane signaling. | lps (endotoxins) activate cells of the human immune system, among which are monocytes and macrophages, to produce endogenous mediators. these regulate the immune response, but may also cause severe harm leading to septic shock. the activation of monocytes/macrophages by lps is mediated by a membrane-bound lps receptor, mcd14. as mcd14 lacks a transmembrane domain, a further protein is required for the signal transducing step to the cell interior. here we show, using excised outside-out membrane ... | 2001 | 11145680 |
| data-quality issues and alternative variable-screening methods in a questionnaire-based study on subclinical salmonella enterica infection in danish pig herds. | our aim was to determine risk factors for subclinical salmonella enterica infection in danish finishing-pig herds. in this paper, the evaluation, combining and initial reduction of variables is presented, along with assessment of the hypotheses in the preliminary statistical testing. the first group of herds was selected at random with no former knowledge of s. enterica infection. both the herd prevalence and the within-herd prevalence among these herds turned out to be low; hence, some addition ... | 2001 | 11150633 |
| genetic mapping by duplication segregation in salmonella enterica. | mudp and mudq elements were used to induce duplications in salmonella enterica by formation of a triple crossover between two transduced fragments and the host chromosome. the large size (36 kb) of mudp and mudq is a favorable trait for duplication formation, probably because homology length is a limiting factor for the central crossover. additional requirements are a multiplicity of infection of 2 or higher in the infecting phage suspensions (which reflects the need of two transduced fragments) ... | 2001 | 11156973 |