Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| parapertussis and pertussis: differences and similarities in incidence, clinical course, and antibody responses. | to compare the incidence, clinical course, and serologic response to bordetella antigens in patients with parapertussis and pertussis. | 1999 | 10460925 |
| an acellular pertussis vaccine in healthy adults: safety and immunogenicity. pennridge pediatric associates. | recent data indicate that bordetella pertussis can be an important cause of illness in adolescents and adults. in a randomized observer- and subject-blinded study, adults (> or = 18 years of age) received an acellular pertussis (ap) vaccine containing genetically inactivated pertussis toxin (pt), filamentous hemagglutinin (fha) and pertactin (prn), or a saline placebo, and were monitored for safety and immunogenicity. igg antibodies to pt, fha, and prn were measured by enzyme-linked immunosorben ... | 1999 | 10462235 |
| antigenic variants in bordetella pertussis strains isolated from vaccinated and unvaccinated children. | bordetella pertussis shows polymorphism in two proteins, pertactin (prn) and the pertussis toxin (pt) s1 subunit, which are important for immunity. a previous study has shown antigenic shifts in these proteins in the dutch b. pertussis population, and it was suggested that these shifts were driven by vaccination. the recent italian clinical trial provided the opportunity to compare the frequencies of prn and pt s1 subunit variants in strains isolated from unvaccinated children, and from children ... | 1999 | 10463173 |
| analysis of bvga activation of the pertactin gene promoter in bordetella pertussis. | bordetella pertussis, the causative agent of whooping cough, regulates expression of its virulence factors via a two-component signal transduction system encoded by the bvg regulatory locus. it has been shown by activation kinetics that several of the virulence factors are differentially regulated. fha is transcribed at 10 min following an inducing signal, while ptx is not transcribed until 2 to 4 h after the inducing signal. we present data indicating that prn is transcribed at 1 h, an intermed ... | 1999 | 10464192 |
| the cpx envelope stress response is controlled by amplification and feedback inhibition. | in escherichia coli, the cpx two-component regulatory system activates expression of protein folding and degrading factors in response to misfolded proteins in the bacterial envelope (inner membrane, periplasm, and outer membrane). it is comprised of the histidine kinase cpxa and the response regulator cpxr. this response plays a role in protection from stresses, such as elevated ph, as well as in the biogenesis of virulence factors. here, we show that the cpx periplasmic stress response is subj ... | 1999 | 10464196 |
| genomic plasticity in natural populations of bordetella pertussis. | we determined the genomic organization of 14 clinical strains of bordetella pertussis isolated over an 18-month period in alberta, canada. the maps of these 14 strains, while demonstrating general similarity of gene order, display a number of examples of genomic rearrangements in the form of large chromosomal inversions. | 1999 | 10464229 |
| asiasari radix inhibits immunoglobulin e production on experimental models in vitro and in vivo. | immunoglobulin (ig) e is the principal ig involved in immediate hypersensitivities and chronic allergic diseases. the hallmark of these disorders is increased ige production. the effect of an aqueous extract of the roots of asiasari radix (arae) on an in vivo and in vitro ige production was investigated. arae dose-dependently inhibited the active systemic anaphylaxis and serum ige production induced by immunization with ovalbumin, bordetella pertussis toxin and aluminum hydroxide gel. arae stron ... | 1999 | 10466075 |
| role of interleukin-4 in down-regulation of contact sensitivity by gammadelta t cells from tolerized t-cell receptor alpha-/- mice. | contact sensitivity (cs) is a classical example of an in vivo t-cell-mediated immune response that is under regulation. such down-regulation can be mediated by alphabeta t cells in mice that are tolerized by prior exposure to high doses of antigen. in contrast, we demonstrated previously that such high-dose antigen tolerance in t-cell receptor (tcr) alpha-/- h-2d mice induced antigen-specific, apparently major histocompatibility complex-unrestricted, cd4- cd8- gammadelta t cells, that also could ... | 1999 | 10469235 |
| inhibition of immunoglobulin e production by poncirus trifoliata fruit extract. | immunoglobulin e (ige) is the principal immunoglobulin involved in immediate hypersensitivities and chronic allergic diseases. the effect of an aqueous extract of poncirus trifoliata (l) raf. (rutaceae) fruits (ptfe) on in vivo and in vitro ige production was investigated. ptfe dose-dependently inhibited the active systemic anaphylaxis and serum ige production induced by immunization with ovalbumin, bordetella pertussis toxin and aluminum hydroxide gel. ptfe strongly inhibited interleukin 4 (il- ... | 1999 | 10473174 |
| genetics of o-antigen biosynthesis in pseudomonas aeruginosa. | pathogenic bacteria produce an elaborate assortment of extracellular and cell-associated bacterial products that enable colonization and establishment of infection within a host. lipopolysaccharide (lps) molecules are cell surface factors that are typically known for their protective role against serum-mediated lysis and their endotoxic properties. the most heterogeneous portion of lps is the o antigen or o polysaccharide, and it is this region which confers serum resistance to the organism. pse ... | 1999 | 10477307 |
| metabolism and genetics of helicobacter pylori: the genome era. | the publication of the complete sequence of helicobacter pylori 26695 in 1997 and more recently that of strain j99 has provided new insight into the biology of this organism. in this review, we attempt to analyze and interpret the information provided by sequence annotations and to compare these data with those provided by experimental analyses. after a brief description of the general features of the genomes of the two sequenced strains, the principal metabolic pathways are analyzed. in particu ... | 1999 | 10477311 |
| helicobacter pylori physiology predicted from genomic comparison of two strains. | helicobacter pylori is a gram-negative bacteria which colonizes the gastric mucosa of humans and is implicated in a wide range of gastroduodenal diseases. this paper reviews the physiology of this bacterium as predicted from the sequenced genomes of two unrelated strains and reconciles these predictions with the literature. in general, the predicted capabilities are in good agreement with reported experimental observations. h. pylori is limited in carbohydrate utilization and will use amino acid ... | 1999 | 10477312 |
| interference with the signaling capacity of cc chemokine receptor 5 can compromise its role as an hiv-1 entry coreceptor in primary t lymphocytes. | 1999 | 10477544 | |
| the b-oligomer of pertussis toxin deactivates cc chemokine receptor 5 and blocks entry of m-tropic hiv-1 strains. | infection of target cells by hiv-1 requires initial binding interactions between the viral envelope glycoprotein gp120, the cell surface protein cd4, and one of the members of the seven-transmembrane g protein-coupled chemokine receptor family. most primary isolates (r5 strains) use chemokine receptor ccr5, but some primary syncytium-inducing, as well as t cell line-adapted, strains (x4 strains) use the cxcr4 receptor. signaling from both ccr5 and cxcr4 is mediated by pertussis toxin (ptx)-sensi ... | 1999 | 10477545 |
| migration of antigen-presenting b cells from peripheral to mucosal lymphoid tissues may induce intestinal antigen-specific iga following parenteral immunization. | parenterally administered immunizations have long been used to induce protection from mucosal pathogens such as bordetella pertussis and influenza virus. we previously found that i.m. inoculation of mice with the intestinal pathogen, rotavirus, induced virus-specific ab production by intestinal lymphocytes. we have now used adoptive transfer studies to identify the cell types responsible for the generation of virus-specific ab production by gut-associated lymphoid tissue (galt) after i.m. immuni ... | 1999 | 10477570 |
| bordetella pertussis, bordetella parapertussis, mycoplasma pneumoniae, chlamydia pneumoniae and persistent cough in children. | material collected during a prospective pertussis vaccine trial in 1992-95 was examined for bordetella pertussis (culture and serology), bordetella parapertussis (culture), mycoplasma pneumoniae and chlamydia pneumoniae (pcr). from 64% (99/155) of episodes with cough for less than 100 d, 115 aetiological agents were identified in one southern and one northern subset of dt-recipients. the most common single agent was b. pertussis, representing 56%(64/115), with a median cough period of 51 d, foll ... | 1999 | 10482058 |
| positive transcriptional feedback controls hydrogenase expression in alcaligenes eutrophus h16. | the protein hoxa is the central regulator of the alcaligenes eutrophus h16 hox regulon, which encodes two hydrogenases, a nickel permease and several accessory proteins required for hydrogenase biosynthesis. expression of the regulatory gene hoxa was analyzed. screening of an 8-kb region upstream of hoxa with a promoter probe vector localized four promoter activities. one of these was found in the region immediately 5' of hoxa; the others were correlated with the nickel metabolism genes hypa1, h ... | 1999 | 10482509 |
| the c-terminal domain of the bordetella pertussis autotransporter brka forms a pore in lipid bilayer membranes. | brka is a 103-kda outer membrane protein of bordetella pertussis that mediates resistance to antibody-dependent killing by complement. it is proteolytically processed into a 73-kda n-terminal domain and a 30-kda c-terminal domain as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. brka is also a member of the autotransporter family of proteins. translocation of the n-terminal domain of the protein across the outer membrane is hypothesized to occur through a pore formed by ... | 1999 | 10482528 |
| identification of a functional fur gene in bradyrhizobium japonicum. | the recent identification of the iron response regulator (irr) in bradyrhizobium japonicum raised the question of whether the global regulator fur is present in that organism. a fur gene homolog was isolated by the functional complementation of an escherichia coli fur mutant. the b. japonicum fur bound to a fur box dna element in vitro, and a fur mutant grown in iron-replete medium was derepressed for iron uptake activity. thus, b. japonicum expresses at least two regulators of iron metabolism. | 1999 | 10482529 |
| detection of prosthetic hip infection at revision arthroplasty by immunofluorescence microscopy and pcr amplification of the bacterial 16s rrna gene. | in this study the detection rates of bacterial infection of hip prostheses by culture and nonculture methods were compared for 120 patients with total hip revision surgery. by use of strict anaerobic bacteriological practice during the processing of samples and without enrichment, the incidence of infection by culture of material dislodged from retrieved prostheses after ultrasonication (sonicate) was 22%. bacteria were observed by immunofluorescence microscopy in 63% of sonicate samples with a ... | 1999 | 10488193 |
| immunogenicity and safety of haemophilus influenzae type b conjugate vaccine (hibtiter) and a combination vaccine of diphtheria, tetanus, pertussis and hibtiter (tetramune) in two-month-old infants. | a study was undertaken to evaluate the safety and immunogenicity of a combination vaccine (tetramune) of conjugate haemophilus influenzae type b (hib) vaccine (hibtiter) and dtp (diphtheria, tetanus and pertussis) vaccine. a total of 93 healthy children were randomized to receive either tetramune (combined group), or dtp and hibtiter administered concurrently (separate group) in separate syringes at approximately 2, 4 and 6 months of age in taiwan. serologic responses were largely comparable bet ... | 1998 | 10496155 |
| humoral and cellular immune responses in mice immunized with recombinant mycobacterium bovis bacillus calmette-guérin producing a pertussis toxin-tetanus toxin hybrid protein. | the development of combined vaccines constitutes one of the priorities in modern vaccine research. one of the most successful combined vaccines in use is the diphtheria-pertussis-tetanus vaccine. however, concerns about the safety of the pertussis arm have led to decreased acceptance of the vaccine but also to the development of new, safer, and effective acellular vaccines against pertussis. unfortunately, the production cost of these new vaccines is significantly higher than that of previous va ... | 1999 | 10496883 |
| use of in vivo-regulated promoters to deliver antigens from attenuated salmonella enterica var. typhimurium. | this study describes the construction and analysis of three in vivo-inducible promoter expression plasmids, containing pnirb, ppagc, and pkatg, for the delivery of foreign antigens in the deltaaroad mutant of salmonella enterica var. typhimurium (hereafter referred to as s. typhimurium). the reporter genes encoding beta-galactosidase and firefly luciferase were used to assess the comparative levels of promoter activity in s. typhimurium in vitro in response to different induction stimuli and in ... | 1999 | 10496887 |
| identification of genes in an extraintestinal isolate of escherichia coli with increased expression after exposure to human urine. | the identification of genes with increased expression in vivo may lead to the identification of novel or unrecognized virulence traits and/or recognition of environmental signals involved in modulating gene expression. our laboratory is studying an extraintestinal isolate of escherichia coli as a model pathogen. we had previously used human urine ex vivo to identify the unrecognized urovirulence genes guaa and argc and to establish that arginine and guanine (or derivatives) were limiting in this ... | 1999 | 10496910 |
| fasciola hepatica suppresses a protective th1 response against bordetella pertussis. | fasciolosis, like other helminth infections, is associated with the induction of t-cell responses polarized to the th2 subtype. respiratory infection with bordetella pertussis or immunization with a pertussis whole-cell vaccine (pw) induces a potent th1 response, which confers a high level of protection against bacterial challenge. we have used these two pathogens to examine bystander cross-regulation of th1 and th2 cells in vivo and provide evidence of immunomodulation of host t-cell responses ... | 1999 | 10496919 |
| functional characterization of a serine/threonine protein kinase of pseudomonas aeruginosa. | protein kinases play a key role in signal transduction pathways in both eukaryotic and prokaryotic cells. using in vivo expression technology, we have identified several promoters in pseudomonas aeruginosa which are preferentially activated during infection of neutropenic mice. one of these promoters directs the transcription of a gene encoding a putative protein kinase similar to the enzymes found in eukaryotic cells. the full characterization of this protein, termed ppka, is presented in this ... | 1999 | 10496921 |
| pseudomonas aeruginosa induces type-iii-secretion-mediated apoptosis of macrophages and epithelial cells. | pseudomonas aeruginosa is a gram-negative opportunistic pathogen that is cytotoxic towards a variety of eukaryotic cells. to investigate the effect of this bacterium on macrophages, we infected j774a.1 cells and primary bone-marrow-derived murine macrophages with the p. aeruginosa strain pa103 in vitro. pa103 caused type-iii-secretion-dependent killing of macrophages within 2 h of infection. only a portion of the killing required the putative cytotoxin exou. by three criteria, terminal deoxynucl ... | 1999 | 10496945 |
| essential role of the iron-regulated outer membrane receptor faua in alcaligin siderophore-mediated iron uptake in bordetella species. | phenotypic analysis using heterologous host systems localized putative bordetella pertussis ferric alcaligin transport genes and fur-binding sequences to a 3.8-kb genetic region downstream from the alcr regulator gene. nucleotide sequencing identified a tonb-dependent receptor family homolog gene, faua, predicted to encode a polypeptide with high amino acid sequence similarity with known bacterial ferric siderophore receptors. in escherichia coli, the faua genes of both b. pertussis and bordetel ... | 1999 | 10498707 |
| mutational analysis of the recj exonuclease of escherichia coli: identification of phosphoesterase motifs. | the recj gene, identified in escherichia coli, encodes a mg(+2)-dependent 5'-to-3' exonuclease with high specificity for single-strand dna. genetic and biochemical experiments implicate recj exonuclease in homologous recombination, base excision, and methyl-directed mismatch repair. genes encoding proteins with strong similarities to recj have been found in every eubacterial genome sequenced to date, with the exception of mycoplasma and mycobacterium tuberculosis. multiple genes encoding protein ... | 1999 | 10498723 |
| representational difference analysis identifies a strain-specific lps biosynthesis locus in bordetella spp. | bordetella pertussis and b. bronchiseptica are genetically very closely related but differ significantly in their virulence properties. using representational difference analysis (rda), 11 dna fragments specific for b. pertussis tohama i or b. bronchiseptica bb7865 were identified. all b. bronchiseptica bb7865-derived fragments also hybridized with chromosomal dna from b. parapertussis but not from the b. pertussis strains tohama i and w28, underlining the close phylogenetic relationship between ... | 1999 | 10503551 |
| a randomized, placebo-controlled trial of erythromycin estolate chemoprophylaxis for household contacts of children with culture-positive bordetella pertussis infection. | household contacts of patients with pertussis are at increased risk of acquiring infection. chemoprophylaxis has been recommended to decrease transmission, particularly to young infants who are at increased risk of severe disease. although epidemiologic investigations of outbreaks have suggested a benefit, there have been no prospective studies evaluating the efficacy of chemoprophylaxis in preventing secondary cases of pertussis. | 1999 | 10506267 |
| heterologous expression of a green fluorescent protein-pertussis toxin s1 subunit fusion construct disrupts calcium channel modulation in rat superior cervical ganglion neurons. | the fusion construct pegfp-ptxs1 was assembled by ligating cdna encoding the s1 subunit of bordetella pertussis toxin (ptx) into the plasmid pegfp-c1 (which codes for enhanced green fluorescent protein). microinjection of pegfp-ptxs1 (1-100 ng/microl) into the nucleus of dissociated rat sympathetic ganglion neurons resulted in functional expression as determined from the diffuse green fluorescence and disruption of norepinephrine-mediated n-type ca2+ channel modulation. the heterologously expres ... | 1999 | 10507694 |
| a homologue of the agrobacterium tumefaciens virb and bordetella pertussis ptl type iv secretion systems is essential for intracellular survival of brucella suis. | analysis of a tnblam mutant of brucella suis 1330, identified as being unable to multiply in hela cells, allowed us to identify a 11 860 bp region of the b. suis genome encoding a type iv secretion system, homologous to the virb system of agrobacterium tumefaciens and the ptl system of bordetella pertussis. dna sequence revealed 12 open reading frames (orfs) encoding homologues of the 11 virb proteins present in the pti plasmid of agrobacterium with a similar genetic organization, and a twelfth ... | 1999 | 10510235 |
| opening the iron box: transcriptional metalloregulation by the fur protein. | 1999 | 10515908 | |
| sequence and organization of pxo1, the large bacillus anthracis plasmid harboring the anthrax toxin genes. | the bacillus anthracis sterne plasmid pxo1 was sequenced by random, "shotgun" cloning. a circular sequence of 181,654 bp was generated. one hundred forty-three open reading frames (orfs) were predicted using genemark and genemark.hmm, comprising only 61% (110,817 bp) of the pxo1 dna sequence. the overall guanine-plus-cytosine content of the plasmid is 32.5%. the most recognizable feature of the plasmid is a "pathogenicity island," defined by a 44.8-kb region that is bordered by inverted is1627 e ... | 1999 | 10515943 |
| disruption of tonb in bordetella bronchiseptica and bordetella pertussis prevents utilization of ferric siderophores, haemin and haemoglobin as iron sources. | the bordetella bronchiseptica tonb gene was cloned by detection of a chromosomal restriction fragment hybridizing with each of two degenerate oligonucleotides that corresponded to pro-glu and pro-lys repeats characteristic of known tonb proteins. the tonb(bb) gene was situated upstream of exbb and exbd homologues and downstream of a putative fur-regulated promoter. hybridization results indicated that the tonb operon and flanking regions were highly conserved between b. bronchiseptica, bordetell ... | 1999 | 10517598 |
| mutants in the ptla-h genes of bordetella pertussis are deficient for pertussis toxin secretion. | the nine ptl genes (a-i) are required for efficient secretion of pertussis toxin past the outer membrane. mutations were made in ptla-h by filling in unique restriction sites, generating in-frame deletions, or inserting a flag epitope tag. the mutations were cloned into a suicide shuttle plasmid containing the ptxptl operon and introduced into the adenylate cyclase locus of the chromosome of a bordetella pertussis strain deleted for ptx. the wild-type ptxptl operon restored pertussis toxin expre ... | 1999 | 10518754 |
| development of a pcr assay for rapid detection of enterococci. | enterococci are becoming major nosocomial pathogens, and increasing resistance to vancomycin has been well documented. conventional identification methods, which are based on culturing, require 2 to 3 days to provide results. pcr has provided a means for the culture-independent detection of enterococci in a variety of clinical specimens and is capable of yielding results in just a few hours. however, all pcr-based assays developed so far are species specific only for clinically important enteroc ... | 1999 | 10523541 |
| compromised ox40 function in cd28-deficient mice is linked with failure to develop cxc chemokine receptor 5-positive cd4 cells and germinal centers. | mice rendered deficient in cd28 signaling by the soluble competitor, cytotoxic t lymphocyte-associated molecule 4-immunoglobulin g1 fusion protein (ctla4-ig), fail to upregulate ox40 expression in vivo or form germinal centers after immunization. this is associated with impaired interleukin 4 production and a lack of cxc chemokine receptor (cxcr)5 on cd4 t cells, a chemokine receptor linked with migration into b follicles. germinal center formation is restored in ctla4-ig transgenic mice by coin ... | 1999 | 10523609 |
| bordetella pertussis and chronic cough in adults. | to evaluate bordetella pertussis as a cause of persistent cough in adults, we examined 201 patients who had a cough for 2-12 weeks and no pulmonary disease. we obtained the following at presentation: medical history, chest radiograph, respiratory function measurement, nasopharyngeal aspirate for polymerase chain reaction (pcr), nasopharyngeal swab specimen for culture, and a blood sample (acute serum). four weeks later a second blood sample (convalescent serum) was obtained. control sera were ob ... | 1999 | 10524969 |
| induction of cd4(+) and cd8(+) bordetella pertussis toxin subunit s1 specific t cells by immunization with synthetic peptides. | in this study two synthetic peptides from the bordetella pertussis toxin subunit s1 were conjugated to human anti-idiotypic antibodies and used as an immunogen in cancer patients to induce immunity. the aims of the present report are to explain why no carrier or adjuvant effect of the conjugated pertussis peptides could be established regarding induction of responses against the anti-idiotype and to explore the type and quality of induced anti-pertussis immune responses. the lack of carrier and ... | 1999 | 10527563 |
| fusidic acid in vitro activity. | fusidic acid is a narrow spectrum agent that acts to inhibit protein synthesis by inhibition of elongation factor g at the level of the ribosome. because of high protein binding susceptibility testing in vitro is affected by the presence of blood or serum. in addition, there is a modest inoculum effect in vitro. a breakpoint of 1 or 2 mg/l is most widely used for defining resistance to systemic treatment with fusidic acid. fusidic acid activity is principally directed at staphylococci, both stap ... | 1999 | 10528786 |
| characterization of pic, a secreted protease of shigella flexneri and enteroaggregative escherichia coli. | we have identified and characterized a secreted protein, designated pic, which is encoded on the chromosomes of enteroaggregative escherichia coli (eaec) 042 and shigella flexneri 2457t. the product of the pic gene is synthesized as a 146.5-kda precursor molecule which is processed at the n and c termini during secretion, allowing the release of a mature protein (109.8 kda) into the culture supernatant. the deduced amino acid sequence of pic shows high homology to autotransporter proteins, parti ... | 1999 | 10531204 |
| bordetella bronchiseptica-mediated cytotoxicity to macrophages is dependent on bvg-regulated factors, including pertactin. | the effect of bordetella bronchiseptica infection on the viability of murine macrophage-like cells and on primary porcine alveolar macrophages was investigated. the bacterium was shown to be cytotoxic for both cell types, particularly where tight cell-to-cell contacts were established. in addition, bvg mutants were poorly cytotoxic for the eukaryotic cells, while a prn mutant was significantly less toxic than wild-type bacteria. b. bronchiseptica-mediated cytotoxicity was inhibited in the presen ... | 1999 | 10531256 |
| importance of b cells, but not specific antibodies, in primary and secondary protective immunity to the intracellular bacterium francisella tularensis live vaccine strain. | although there appears to be little if any role for specific antibodies in protection against intracellular bacteria, such as the model pathogen f. tularensis live vaccine strain (lvs), the role of b cells themselves in primary and secondary infection with such bacteria has not been examined directly. we show here that mice deficient in mature b cells and antibodies (b-cell knockout mice) are marginally compromised in controlling primary sublethal infection but are 100-fold less well protected a ... | 1999 | 10531260 |
| pregenomic comparative analysis between bordetella bronchiseptica rb50 and bordetella pertussis tohama i in murine models of respiratory tract infection. | we describe here a side-by-side comparison of murine respiratory infection by bordetella pertussis and bordetella bronchiseptica strains whose genomes are currently being sequenced (tohama i and rb50, respectively). b. pertussis and b. bronchiseptica are most appropriately classified as subspecies. their high degree of genotypic and phenotypic relatedness facilitates comparative studies of pathogenesis. rb50 and tohama i differ in their abilities to grow in the nose, trachea, and lungs of balb/c ... | 1999 | 10531274 |
| in azotobacter vinelandii, the e1 subunit of the pyruvate dehydrogenase complex binds fpr promoter region dna and ferredoxin i. | in azotobacter vinelandii, deletion of the fdxa gene that encodes a well characterized seven-iron ferredoxin (fdi) is known to lead to overexpression of the fdi redox partner, nadph:ferredoxin reductase (fpr). previous studies have established that this is an oxidative stress response in which the fpr gene is transcriptionally activated to the same extent in response to either addition of the superoxide propagator paraquat to the cells or to fdxa deletion. in both cases, the activation occurs th ... | 1999 | 10535932 |
| in vivo induction of ctl responses by recombinant adenylate cyclase of bordetella pertussis carrying multiple copies of a viral cd8(+) t-cell epitope. | bordetella pertussis adenylate cyclase toxin (act) is one of the few known protein toxins penetrating directly into the cytosol of target cells across their cytoplasmic membrane without the need for endocytosis. this capacity of act was recently exploited for in vivo delivery of single viral cd8(+) t-epitopes into mhc class i-presenting cells and induction of protective antiviral cytotoxic t-cell (ctl) responses. here, we have explored the potential of the cell-invasive adenylate cyclase domain ... | 1999 | 10536304 |
| activation of complement receptor 3 on human monocytes by cross-linking of very-late antigen-5 is mediated via protein tyrosine kinases. | bordetella pertussis interacts with very-late antigen-5 (vla-5) receptors on the human monocyte resulting in cross-linking of these receptors followed by activation of complement receptor 3 (cr3) and firm adhesion of b. pertussis to these monocytes. in the present study we investigated whether protein tyrosine kinases are involved in the activation of cr3 on monocytes, which was assessed by the binding of c3bi-coated erythrocytes (ec3bi). pre-incubation of monocytes with tyrphostin-a47, a specif ... | 1999 | 10540218 |
| the agrobacterium tumefaciens chaperone-like protein, vire1, interacts with vire2 at domains required for single-stranded dna binding and cooperative interaction. | agrobacterium tumefaciens transfers single-stranded dna (ssdna) into plants. efficient tumorigenesis requires vire1-dependent export of ssdna-binding (ssb) protein vire2. vire1 binds vire2 domains involved in ssb and self-association, and vire1 may facilitate vire2 export by preventing vire2 aggregation and the premature binding of vire2 to ssdna. | 1999 | 10542192 |
| protein-mediated adhesion of the dissimilatory fe(iii)-reducing bacterium shewanella alga bry to hydrous ferric oxide. | the rate and extent of bacterial fe(iii) mineral reduction are governed by molecular-scale interactions between the bacterial cell surface and the mineral surface. these interactions are poorly understood. this study examined the role of surface proteins in the adhesion of shewanella alga bry to hydrous ferric oxide (hfo). enzymatic degradation of cell surface polysaccharides had no effect on cell adhesion to hfo. the proteolytic enzymes streptomyces griseus protease and chymotrypsin inhibited t ... | 1999 | 10543817 |
| rational medium design for bordetella pertussis: basic metabolism. | in current bordetella pertussis media ammonium accumulates because of an imbalance in the nitrogen:carbon ratio of the substrates used, which is one of the factors limiting cell density in fed-batch cultures. the aim of this study was to map b. pertussis catabolic and anabolic capabilities, in order to design a medium that avoids ammonium accumulation, while substrates are metabolised completely. besides the known dysfunctional glycolysis, b. pertussis also possessed a partially dysfunctional ci ... | 1999 | 10553654 |
| characterization of the essential transport function of the aida-i autotransporter and evidence supporting structural predictions. | the current model for autodisplay suggests a mechanism that allows a passenger protein to be translocated across the outer membrane by coordinate action of a c-terminal beta-barrel and its preceding linking region. the passenger protein, linker, and beta-barrel are together termed the autotransporter, while the linker and beta-barrel are here referred to as the translocation unit (tu). we characterized the minimal tu necessary for autodisplay with the adhesin-involved-in-diffuse-adherence (aida- ... | 1999 | 10559167 |
| molecular diagnosis of chlamydia pneumoniae infection. | 1999 | 10565886 | |
| development of a nitric oxide induction assay as a potential replacement for the intracerebral mouse protection test for potency assay of pertussis whole cell vaccines. | the intracerebral mouse protection test (kendrick test) for the potency assay of pertussis vaccines is a complex and time consuming in vivo test which has a significant intra- and interlaboratory variation. thus, there is a pressing need to develop a replacement for the kendrick test. there is now convincing evidence to suggest that bordetella pertussis can be taken up and survive within macrophages in the lungs and that cell-mediated immunity plays a role in protection. it was hypothesised that ... | 1999 | 10566781 |
| toxicity tests on native and recombinant bordetella pertussis adenylate cyclase toxin preparations. | bordetella pertussis produces a cell-invasive adenylate cyclase toxin which is synthesised from the cyaa gene as an inactive protoxin that is post-translationally activated by the product of the cyac gene. active and inactive cyaa proteins were prepared in crude and purified form from b. pertussis or from recombinant e. coli expressing both cyaa and cyac genes or the cyaa gene alone, respectively. the specific ac activities of all the crude or all the purified toxins were similar. the toxins pro ... | 1999 | 10566788 |
| mutants of escherichia coli heat-labile toxin act as effective mucosal adjuvants for nasal delivery of an acellular pertussis vaccine: differential effects of the nontoxic ab complex and enzyme activity on th1 and th2 cells. | mucosal delivery of vaccines is dependent on the identification of safe and effective adjuvants that can enhance the immunogenicity of protein antigens administered by nasal or oral routes. in this study we demonstrate that two mutants of escherichia coli heat-labile toxin (lt), ltk63, which lacks adp-ribosylating activity, and ltr72, which has partial enzyme activity, act as potent mucosal adjuvants for the nasal delivery of an acellular pertussis (pa) vaccine. both ltk63 and ltr72 enhanced ant ... | 1999 | 10569737 |
| identification of a novel mycobacterial histone h1 homologue (hupb) as an antigenic target of panca monoclonal antibody and serum immunoglobulin a from patients with crohn's disease. | panca is a marker antibody associated with inflammatory bowel disease (ibd), including most patients with ulcerative colitis and a subset with crohn's disease. this study addressed the hypothesis that panca reacts with an antigen(s) of microbial agents potentially relevant to ibd pathogenesis. using a panca monoclonal antibody, we have previously identified the c-terminal basic random-coil domain of histone h1 as a panca autoantigen. blast analysis of the peptide databases revealed h1 epitope ho ... | 1999 | 10569769 |
| rna polymerase alpha and sigma(70) subunits participate in transcription of the escherichia coli uhpt promoter. | fundamental questions in bacterial gene regulation concern how multiple regulatory proteins interact with the transcription apparatus at a single promoter and what are the roles of protein contacts with rna polymerase and changes in dna conformation. transcription of the escherichia coli uhpt gene, encoding the inducible sugar phosphate transporter, is dependent on the response regulator uhpa and is stimulated by the cyclic amp receptor protein (cap). uhpa binds to multiple sites in the uhpt pro ... | 1999 | 10572130 |
| direct selection of is903 transposon insertions by use of a broad-host-range vector: isolation of catalase-deficient mutants of actinobacillus actinomycetemcomitans. | transposon mutagenesis in bacteria generally requires efficient delivery of a transposon suicide vector to allow the selection of relatively infrequent transposition events. we have developed an is903-based transposon mutagenesis system for diverse gram-negative bacteria that is not limited by transfer efficiency. the transposon, is903phikan, carries a cryptic kan gene, which can be expressed only after successful transposition. this allows the stable introduction of the transposon delivery vect ... | 1999 | 10572134 |
| transcription regulation of the colicin k cka gene reveals induction of colicin synthesis by differential responses to environmental signals. | colicin-producing strains occur frequently in natural populations of escherichia coli, and colicinogenicity seems to provide a competitive advantage in the natural habitat. a cka-lacz fusion was used to study the regulation of expression of the colicin k structural gene. expression is growth phase dependent, with high activity in the late stationary phase. nutrient depletion induces the expression of cka due to an increase in ppgpp. temperature is a strong signal for cka expression, since only b ... | 1999 | 10572143 |
| the 7alpha-hydroxysteroids produced in human tonsils enhance the immune response to tetanus toxoid and bordetella pertussis antigens. | human tonsils were assessed for their ability to 7alpha-hydroxylate pregnenolone (preg), dehydroepiandrosterone (dhea) and 3-epiandrosterone (epia). both 7alpha-hydroxy-dhea and 7alpha-hydroxy-epia were produced by homogenates of either whole tonsils or of lymphocyte-depleted tonsil fractions. in contrast, isolated lymphocytes were found to be unable to carry out 7alpha-hydroxylation. when co-cultures of tonsil-derived t and b lymphocytes were set up under stimulatory conditions, iggs were relea ... | 1999 | 10572944 |
| evidence for an intracellular niche for bordetella pertussis in broncho-alveolar lavage cells of mice. | bordetella pertussis can attach, invade and survive intracellularly in human macrophages in vitro. to study the significance of this bacterial feature in vivo, we analyzed the presence of viable bacteria in broncho-alveolar lavage (bal) cells of mice infected with b. pertussis. we found b. pertussis to be present in a viable state in bal fluid cells until at least 19 days after infection, suggesting b. pertussis to be able to survive in those cells. this intracellular niche may play an important ... | 1999 | 10575131 |
| cloning and immunologic characterization of a truncated bordetella bronchiseptica filamentous hemagglutinin fusion protein. | filamentous hemagglutinin (fha) is an outer-membrane associated adhesin conserved within the genus bordetella. fha provides protection against b. pertussis infections in humans and is a component of acellular whooping cough vaccines. furthermore, fha serves as a protective antigen in several animal models of infection with b. bronchiseptica and may serve as a protective antigen of canine bordetellosis. in this study, polyclonal anti-b. pertussis fha antiserum was used to identify an immunoreacti ... | 1999 | 10580199 |
| usefulness of pulsed-field gel electrophoresis in assessing nosocomial transmission of pertussis. | during a 2-week period, three infants with a cough lasting at least 8 days with whoops, were admitted to the pediatric unit; bordetella pertussis was isolated from nasopharyngeal aspirates collected from the three infants. approximately 1 week later, a nurse working on the same unit developed influenza-like symptoms followed by whooping cough; b pertussis was isolated. isolates from the nurse and from one of the infants were shown to be indistinguishable by pulsed-field gel electrophoresis. thes ... | 1999 | 10580628 |
| resistance of young gelatinase b-deficient mice to experimental autoimmune encephalomyelitis and necrotizing tail lesions. | regulated expression of matrix metalloproteinases (mmps) and their inhibitors (timps) plays a role in various physiological processes. to determine in vivo how unbalanced expression of these factors can promote or affect the course of pathologies, we knocked out the mouse gelatinase b gene by replacing the catalytic and zinc-binding domains with an antisense-oriented neomycin resistance gene. adult gelatinase b-deficient mice and wild-type controls could be induced to develop experimental autoim ... | 1999 | 10587514 |
| the bpel locus encodes type iii secretion machinery in bordetella pertussis. | type iii secretory genes(bscl, j, k, l, n and o) have recently been identified in bordetella bronchiseptica and shown to be under the control of the bvgas locus. we examined a 35 616 byte dna sequence amplified from bordetella pertussis tohama i for homology with known type iii secretory genes in yersinia spp. and pseudomonas sppand a total of 20 homologous open reading frames were detected. putative type iii secretion proteins in b. pertussis were designated according to their homology with typ ... | 1999 | 10588908 |
| acute laryngitis in the rat induced by moraxella catarrhalis and bordetella pertussis: number of neutrophils, dendritic cells, and t and b lymphocytes accumulating during infection in the laryngeal mucosa strongly differs in adjacent locations. | infectious laryngotracheitis results in fulminant respiratory distress. during the disease, the subglottic mucosa is selectively infected and swollen, the reason for this preference being unknown. therefore, in the present study the immunoreaction of the laryngeal mucosa was studied in the rat after inhalation of either heat-killed moraxella catarrhalis (pvg rats) or application of viable bordetella pertussis (bn rats). the number of neutrophils, macrophages, dendritic cells, and t and b lymphoc ... | 1999 | 10590036 |
| induction of a specific antibody response to bordetella pertussis antigens in cultures of human peripheral blood mononuclear cells. | the role of specific antibodies in protective immunity to bordetella pertussis has not yet been clearly defined. in the present work, the induction of a specific antibody response to b. pertussis in cultures of human peripheral blood mononuclear cells (pbmc) was investigated, on the assumption that the capacity of circulating lymphocytes to mount a specific response in vitro may provide a useful parameter for the evaluation of protective immunity. when pbmc from normal adult donors were cultured ... | 1999 | 10591161 |
| tmrdb (tmrna database). | the tmrna database (tmrdb) is maintained at the university of texas health science center at tyler, texas, and is accessible on the www at url http://psyche.uthct.edu/dbs/tmrdb/tmrdb.++ +html. a tmrdb mirror site is located on the campus of auburn university, auburn, alabama, reachable at the url http://www.ag.auburn.edu/mirror/tmrdb/. since april 1997, the tmrdb has provided sequences of tmrna (previously called 10sa rna), a molecule present in most bacteria and some organelles. this release ad ... | 2000 | 10592214 |
| production and purification of bordetella pertussis toxin. | pertussis toxin (pt) is the major protective antigen of acellular pertussis vaccine (ap). we have established an optimal culture condition for the growth of b. pertussis and the production of pt in a laboratory scale fermentor. it was found that when the dissolved oxygen in medium was supplied with pure oxygen instead of air, the yield of pt was dramatically increased (i.e. from 2-3 mg/l using air to 8-10 mg/l using pure oxygen). pt was purified by affinity chromatography using hydroxyapatite an ... | 1997 | 10592813 |
| preparation and characterization of pertussis toxin subunits. | pertussis toxin (pt), a typical a-b oligomer exotoxin of bordetella pertussis, has been demonstrated to be an essential protective antigen for acellular pertussis vaccine against whooping cough. in order to investigate the associated functionality ascribed to its components, we have purified a and b oligomers for the activity study. the a oligomer (s1 subunit) of pt was expressed in e. coli b834 (de3) harboring expression vector (pet-20b) with the insert of s1 coding region and purified by metal ... | 1997 | 10592823 |
| apoptosis of cd4+ t cells occurs in experimental autoimmune anterior uveitis (eaau). | to investigate the spontaneous turning off mechanism of endogenous uveitis, eaau was induced in lewis rats. immunohistochemical and terminal deoxynucleotidyl transferase-mediated dutp nick end labelling (tunel) stains revealed that cd4+ t cells were predominant in the uveal tissue of eaau and that the apoptosis of these cells had occurred and progressed throughout the inflammatory period in eaau eyes. the immunohistochemistry and in situ hybridization for fas ligand (fasl) expression showed that ... | 1999 | 10594552 |
| [new vaccines against bordetella pertussis]. | 1996 | 10596079 | |
| development of acellular pertussis vaccines. | in 1974, the authors reported the isolation and characterization of protective antigens of bordetella pertussis in mice. with this information, an acellular pertussis vaccine was developed, composed mainly of pertussis toxin (pt) and filamentous haemagglutinin (fha). substances causing side effects, especially lipopoly sacahoride (lps) or endotoxin that cause fever, were removed, and detoxification of the pt by formaldehyde with retention of potency was achieved. in 1981, an acellular pertussis ... | 1999 | 10600185 |
| review of the biology of bordetella pertussis. | bordetella pertussis produces a complex array of adhesins, aggressins and toxins that are presumed to be important in the colonisation of its human host and in ensuring its survival and propagation. the organism also has highly sophisticated mechanisms for regulating virulence factor expression, in response to environmental signals or by reversible mutations. despite the rapidly increasing knowledge of these aspects of the biology of b. pertussis, our understanding of the pathogenesis of whoopin ... | 1999 | 10600186 |
| the immunology of bordetella pertussis infection. | 1999 | 10600187 | |
| acellular pertussis vaccines: neutralization by immune sera of the lethality of pertussis toxin and viable bordetella pertussis for chick embryos. | vaccines containing acellular pertussis components, either separate or combined with other microbial antigens, were evaluated for specific immune responses in guinea-pigs and mice. the capacity of sera to protect chick embryos from the lethal effect of pertussis toxin was independent of the chinese hamster ovary cell clumping neutralization titre and the antigen binding elisa anti-toxin titre. direct correlations did not exist between elisa titres to pt, fha, fimbria or 69 kda and capacity to pr ... | 1999 | 10600203 |
| physico-chemical analysis of bordetella pertussis antigens. | physico-chemical methods are being developed for use in the control and standardization of acellular pertussis vaccines and their individual components. we have compared native and detoxified preparations of the b. pertussis antigens, pertussis toxin (pt), filamentous haemagglutinin (fha), and the 69-kda outer membrane protein (p69) using circular dichroism (cd), fluorescence spectroscopy, sds-page and fplc gel filtration chromatography. upon aldehyde detoxification, pt underwent a large change ... | 1999 | 10600205 |
| functional domains present in the mycobacterial hemagglutinin, hbha. | identification and characterization of mycobacterial adhesins and complementary host receptors required for colonization and dissemination of mycobacteria in host tissues are needed for a more complete understanding of the pathogenesis of diseases caused by these bacteria and for the development of effective vaccines. previous investigations have demonstrated that a 28-kda heparin-binding mycobacterial surface protein, hbha, can agglutinate erythrocytes and promote mycobacterial aggregation in v ... | 1999 | 10601202 |
| multiple control of flagellum biosynthesis in escherichia coli: role of h-ns protein and the cyclic amp-catabolite activator protein complex in transcription of the flhdc master operon. | little is known about the molecular mechanism by which histone-like nucleoid-structuring (h-ns) protein and cyclic amp-catabolite activator protein (cap) complex control bacterial motility. in the present paper, we show that crp and hns mutants are nonmotile due to a complete lack of flagellin accumulation. this results from a reduced expression in vivo of flia and flic, which encode the specific flagellar sigma factor and flagellin, respectively. overexpression of the flhdc master operon restor ... | 1999 | 10601207 |
| 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 |
| delivery of cd8(+) t-cell epitopes into major histocompatibility complex class i antigen presentation pathway by bordetella pertussis adenylate cyclase: delineation of cell invasive structures and permissive insertion sites. | bordetella pertussis adenylate cyclase (ac) toxin-hemolysin (act-hly) can penetrate a variety of eukaryotic cells. recombinant ac toxoids have therefore been recently used for delivery of cd8(+) t-cell epitopes into antigen-presenting cells in vivo and for induction of protective antiviral, as well as therapeutic antitumor cytotoxic t-cell responses. we have explored the carrier potential of the act molecule by insertional mutagenesis scanning for new permissive sites, at which integration of tw ... | 2000 | 10603395 |
| in vitro brucella suis infection prevents the programmed cell death of human monocytic cells. | during the complex interaction between an infectious agent and a host organism, the pathogen can interfere with the host cell's programmed death to its own benefit. induction or prevention of host cell apoptosis appears to be a critical step for determining the infection outcome. members of the gram-negative bacterial genus brucella are intracellular pathogens which preferentially invade monocytic cells and develop within these cells. we investigated the effect of brucella suis infection on apop ... | 2000 | 10603407 |
| molecular approaches for safer and stronger vaccines. | progress in molecular biology and biotechnology is making possible the development of new vaccines or the improvement of already existing ones. recombinant dna technology, genetic attenuation of bacterial and viral pathogens and their use as vectors for heterologous proteins, expression of microbial antigens in transgenic edible plants, and naked nucleic acid technology represent the most popular approaches hitherto adopted. a successful biotechnological approach to the development of new and im ... | 1999 | 10603647 |
| evidence for transmission of pertussis in schools, massachusetts, 1996: epidemiologic data supported by pulsed-field gel electrophoresis studies. | in 1996, 18 of 20 pertussis outbreaks reported in massachusetts occurred in schools. pertussis surveillance data were reviewed and a retrospective cohort study was conducted in a high school that experienced an outbreak. bordetella pertussis isolates from 9 school cases and from 58 cases statewide were examined by use of pulsed-field gel electrophoresis (pfge). statewide incidence rates were highest among children aged <1 year, 10-14 years, and 15-19 years (106, 117, and 104 cases per 100,000, r ... | 2000 | 10608769 |
| an amphipathic alpha-helix including glutamates 509 and 516 is crucial for membrane translocation of adenylate cyclase toxin and modulates formation and cation selectivity of its membrane channels. | the bordetella pertussis adenylate cyclase toxin-hemolysin (act or cyaa) is a multifunctional protein. it forms small cation-selective channels in target cell and lipid bilayer membranes and it delivers into cell cytosol the amino-terminal adenylate cyclase (ac) domain, which catalyzes uncontrolled conversion of atp to camp and causes cell intoxication. here, we demonstrate that membrane translocation of the ac domain into cells is selectively dissociated from act membrane insertion and channel ... | 1999 | 10608820 |
| channel formation by fhac, the outer membrane protein involved in the secretion of the bordetella pertussis filamentous hemagglutinin. | many virulence factors of pathogenic microorganisms are presented at the cell surface. however, protein secretion across the outer membrane of gram-negative bacteria remains poorly understood. here we used the extremely efficient secretion of the bordetella pertussis filamentous hemagglutinin (fha) to decipher this process. fha secretion requires a single specific accessory protein, fhac, the prototype of a family of proteins necessary for the extracellular localization of various virulence prot ... | 1999 | 10608832 |
| the virr response regulator from clostridium perfringens binds independently to two imperfect direct repeats located upstream of the pfoa promoter. | regulation of toxin production in the gram-positive anaerobe clostridium perfringens occurs at the level of transcription and involves a two-component signal transduction system. the sensor histidine kinase is encoded by the virs gene, while its cognate response regulator is encoded by the virr gene. we have constructed a virr expression plasmid in escherichia coli and purified the resultant his-tagged virr protein. gel mobility shift assays demonstrated that virr binds to the region upstream of ... | 2000 | 10613863 |
| the efficacy of laboratory diagnosis of helicobacter pylori infections in gastric biopsy specimens is related to bacterial density and vaca, caga, and icea genotypes. | a total of 500 consecutive patients undergoing upper endoscopy were biopsied and tested for h. pylori infection by the campylobacter-like organism (clo) test, culture, histology, and pcr. serum samples were tested by two different serological assays. patients were considered h. pylori positive if at least two of the four biopsy specimen-based methods yielded positive results. pcr had the highest diagnostic sensitivity (99.4%), followed by histology (92.2%), culture (89.5%), and the clo test (89. ... | 2000 | 10618055 |
| polymorphism in the pertussis toxin promoter region affecting the dna-based diagnosis of bordetella infection. | the pertussis toxin (pt) promoter region is a frequently used target for dna-based diagnosis of pertussis and parapertussis infections. the reported polymorphism in this region has also allowed discrimination of species in mixtures with several bordetella species by their specific pcr amplicon restriction patterns. in the present study, we investigated the degree of polymorphism in order to confirm the reliability of the assay. five different sequence types of the amplified 239- or 249-bp region ... | 2000 | 10618063 |
| caga antibodies in japanese children with nodular gastritis or peptic ulcer disease. | caga(+) helicobacter pylori strains have been linked to more severe gastric inflammation, peptic ulcer disease, and gastric cancer in adults, but there have been few studies of caga in children. we examined the relationship between h. pylori caga status and clinical status in japanese children. forty h. pylori-positive children were studied: 15 with nodular gastritis, 5 with gastric ulcers, and 20 with duodenal ulcers. h. pylori status was confirmed by biopsy-based tests and serum anti-h. pylori ... | 2000 | 10618065 |
| an adult formulation of a five-component acellular pertussis vaccine combined with diphtheria and tetanus toxoids is safe and immunogenic in adolescents and adults. | pertussis is increasingly being recognized as an important cause of cough illness in adolescents and adults. to evaluate the safety and immunogenicity of an adult formulation of a five-component (pertussis toxoid, filamentous hemagglutinin, pertactin, fimbriae 2 and 3) acellular pertussis vaccine combined with diphtheria and tetanus toxoids, we randomly allocated 749 healthy adolescents and adults from 12-54 years of age recruited from five canadian communities to receive either tetanus-diphther ... | 2000 | 10618527 |
| [induction of protective immunity for bordetella pertussis by nasal inoculation of pertussis vaccine in mice]. | although nasal vaccination has emerged as an interesting alternative to intramuscular or oral vaccination, knowledge is scarce about the immune responses after such immunization. in the present study, we inoculated purified pertussis toxin (pt) and filamentous haemagglutinin (fha) with or without adjuvant (kayexalate), or diphtheria acellular pertussis tetanus (dapt) combined vaccine to mice intranasally three times every four weeks to investigate the references of the immunoresponses between na ... | 1999 | 10624095 |
| differential processing of propeptide inhibitors of rap phosphatases in bacillus subtilis. | in the phosphorelay signal transduction system for sporulation initiation in bacillus subtilis, the opposing activities of histidine kinases and aspartyl phosphate phosphatases determine the cell's decision whether to continue with vegetative growth or to initiate the differentiation process. regulated dephosphorylation of the spo0a and spo0f response regulators allows a variety of negative signals from physiological processes that are antithetical to sporulation to impact on the activation leve ... | 2000 | 10629174 |
| identification of a mycobacterium tuberculosis gene that enhances mycobacterial survival in macrophages. | intracellular survival plays a central role in the pathogenesis of mycobacterium tuberculosis. to identify m. tuberculosis genes required for intracellular survival within macrophages, an m. tuberculosis h37rv plasmid library was constructed by using the shuttle vector polyg. this plasmid library was electroporated into mycobacterium smegmatis 1-2c, and the transformants were used to infect the human macrophage-like cell line u-937. because m. smegmatis does not readily survive within macrophage ... | 2000 | 10629183 |
| use of heme compounds as iron sources by pathogenic neisseriae requires the product of the hemo gene. | heme compounds are an important source of iron for neisseriae. we have identified a neisserial gene, hemo, that is essential for heme, hemoglobin (hb), and haptoglobin-hb utilization. the hemo gene is located 178 bp upstream of the hmbr hb receptor gene in neisseria meningitidis isolates. the product of the hemo gene is homologous to enzymes that degrade heme; 21% of its amino acid residues are identical, and 44% are similar, to those of the human heme oxygenase-1. dna sequences homologous to he ... | 2000 | 10629191 |
| 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 |
| overexpression of the rna polymerase alpha subunit reduces transcription of bvg-activated virulence genes in bordetella pertussis. | overexpression of the rna polymerase alpha subunit in bordetella pertussis reduces expression of the virulence factor pertussis toxin. here we show that this reduction is at the level of transcription, is reversed by overexpression of the transcriptional activator bvga, and is dependent on the c-terminal domain of alpha. | 2000 | 10629205 |
| discovery of a nonclassical siderophore, legiobactin, produced by strains of legionella pneumophila. | the mechanisms by which legionella pneumophila, a facultative intracellular parasite and the agent of legionnaires' disease, acquires iron are largely unexplained. several earlier studies indicated that l. pneumophila does not elaborate siderophores. however, we now present evidence that supernatants from l. pneumophila cultures can contain a nonproteinaceous, high-affinity iron chelator. more specifically, when aerobically grown in a low-iron, chemically defined medium (cdm), l. pneumophila sec ... | 2000 | 10633110 |