| serosurvey for selected disease agents in white-tailed deer from mexico. | serum samples from 350 white-tailed deer (odocoileus virginianus texanus) collected in march 1994 from northeastern mexico were tested for the prevalence of antibody activity against five infectious diseases of ruminants. the prevalence rate was 81% for bluetongue virus (btv) of all serotypes, 72% for epizootic hemorrhagic disease virus (ehdv), 3% for borrelia burgdorferi, 69% for anaplasma marginale, and 0% for brucella abortus, b. melitensis, and b. ovis. these are diseases that affect domesti ... | 1999 | 10574545 |
| brucellosis induced by rb51 vaccine in a pregnant heifer. | brucellosis developed in a 14.5-month-old gelbvieh heifer after the animal was vaccinated with the calfhood dose of strain rb51 brucella abortus vaccine s.c. during the fourth month of its first pregnancy. the heifer experienced dystocia and was euthanatized during cesarean section because of a large uterine tear. the fetus was dead at delivery. suppurative placentitis and fetal pneumonia were evident at necropsy. brucella abortus strain rb51 was isolated from the placenta and the fetus' lung. | 1999 | 10579049 |
| systemic mycobacterial infection inhibits antigen-specific immunoglobulin e production, bronchial mucus production and eosinophilic inflammation induced by allergen. | as the burden of infectious diseases becomes reduced in many countries, a remarkable increase in the incidence of allergies has occurred. the basis for the rise in atopic disorders as a correlate of the decline in infectious diseases has not been defined. in the present study, we tested experimentally whether prior systemic infection with mycobacterium bovis bacillus calmette guérin (bcg) had any effect on ovalbumin (ova) al(oh)3 (alum)-induced immunoglobulin e (ige) production, airway mucus pro ... | 1999 | 10583590 |
| differential secretion of interleukin-12 (il-12) subunits and heterodimeric il-12p70 protein by cd-1 mice and murine macrophages in response to intracellular infection by brucella abortus. | the secretion of interleukin-12 (il-12) following intracellular infection with virulent brucella abortus strain 2308 was investigated in cd-1 mice and in cd-1 cultured peritoneal macrophages. bioactive il-12p70 and free non-immunoactive p40 subunits (il-12p40) were determined by enzyme-linked immunosorbent assays. in cd-1 mice, b. abortus 2308 was a potent inducer of il-12p40 (maximum levels were 5.9 and 3.4 ng/ml in sera and spleen homogenates, respectively). secretion of il-12p70 was also demo ... | 1999 | 10591159 |
| increased expression of periplasmic cu,zn superoxide dismutase enhances survival of escherichia coli invasive strains within nonphagocytic cells. | we have studied the influence of periplasmic cu,zn superoxide dismutase on the intracellular survival of escherichia coli strains able to invade epithelial cells by the expression of the inv gene from yersinia pseudotuberculosis but unable to multiply intracellularly. intracellular viability assays, confirmed by electron microscopy observations, showed that invasive strains of e. coli engineered to increase cu,zn superoxide dismutase production are much more resistant to intracellular killing th ... | 2000 | 10603365 |
| effects of opsonization and gamma interferon on growth of brucella melitensis 16m in mouse peritoneal macrophages in vitro. | entry of opsonized pathogens into phagocytes may benefit or, paradoxically, harm the host. opsonization may trigger antimicrobial mechanisms such as reactive oxygen or nitric oxide (no) production but may also provide a safe haven for intracellular replication. brucellae are natural intramacrophage pathogens of rodents, ruminants, dogs, marine mammals, and humans. we evaluated the role of opsonins in brucella-macrophage interactions by challenging cultured murine peritoneal macrophages with bruc ... | 2000 | 10603396 |
| 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 |
| characterization of a macrophage-specific infectivity locus (mila) of legionella pneumophila. | legionella pneumophila has been shown to possess multiple genetic loci that play roles in its ability to survive within host cells. the mil (macrophage-specific infectivity loci) mutants of l. pneumophila exhibit a spectrum of defects in intracellular survival in and cytopathogenicity to macrophages and alveolar epithelial cells. this study characterizes one of the mil mutants (gb111). intracellular growth of gb111 in macrophages was approximately 100- to 1,000-fold less than that of aa100, the ... | 2000 | 10603410 |
| a screening elisa for brucellosis in reindeer. | an enzyme-linked immunosorbent assay (elisa) for the screening of brucellosis in reindeer was developed. the assay, which utilizes s-lps from brucella abortus as antigen and biotin-labelled rabbit antibody to reindeer immunoglobulin as detecting antibody, has a high specificity and sensitivity, as indicated in a validation with sera from reindeer cultured positive for brucella suis biovar 4 and sera from reindeer free of brucellosis. | 1999 | 10605375 |
| detection of francisella tularensis in biological specimens using a capture enzyme-linked immunosorbent assay, an immunochromatographic handheld assay, and a pcr. | the early detection of francisella tularensis, the causative agent of tularemia, is important for adequate treatment by antibiotics and the outcome of the disease. here we describe a new capture enzyme-linked immunosorbent assay (celisa) based on monoclonal antibodies specific for lipopolysaccharide (lps) of francisella tularensis subsp. holarctica and francisella tularensis subsp. tularensis. no cross-reactivity with francisella tularensis subsp. novicida, francisella philomiragia, and a panel ... | 2000 | 10618283 |
| characterization of specific immune responses of mice inoculated with recombinant vaccinia virus expressing an 18-kilodalton outer membrane protein of brucella abortus. | using the shuttle vector pmco2 and the vaccinia virus wild-type wr strain, we constructed a recombinant virus expressing an 18-kda outer membrane protein of brucella abortus. balb/c mice inoculated with this virus produced 18-kda protein-specific antibodies, mostly of immunoglobulin g2a isotype, and in vitro stimulation of splenocytes from these mice with purified maltose binding protein-18-kda protein fusion resulted in lymphocyte proliferation and gamma interferon production. however, these mi ... | 2000 | 10618289 |
| experimental brucella abortus induced abortion in a llama: pathologic effects. | brucella abortus infection has not been documented in llamas. this report describes the abortion of the only pregnant animal in a group of 12. the llama was infected by inoculating 1 x 10(8) viable b. abortus organisms into the conjunctival sac. forty-three days postinfection, the llama aborted a fetus of approximately 8 months gestational age. brucella organisms were isolated from the placenta and all fetal specimens examined. these organisms were also isolated from the dam's mammary gland and ... | 2000 | 10643984 |
| evaluation of three brucella soluble antigens used in an indirect elisa to discriminate s19 vaccinated from naturally infected cattle. | an o-polysaccharide (o-chain) and a hot-water extracted polysaccharide (ps), both obtained from brucella abortus 1119-3, and a b. melitensis 16m native hapten (nh) were evaluated by indirect enzyme linked immunosorbent assay (elisa) on three groups of cattle sera. the sera tested were: (a) 75 sera from cows naturally infected with b. abortus; (b) 130 sera from non-infected and non-vaccinated cattle; and (c) 61 sera from non-infected heifers recently vaccinated with b. abortus strain 19 (s19). se ... | 2000 | 10665543 |
| identification and partial characterisation of a new protective antigen of brucella abortus. | two novel brucella abortus proteins were isolated from b. abortus strain rb51 and their immunological properties were determined. these proteins precipitated in the 40-60% saturated concentration range of ammonium sulphate and had a molecular mass of 32.2 kda and 22.9 kda, respectively. both were able to induce a strong in-vitro blast transformation in lymphoid cells obtained from mice previously sensitised with a crude brucella protein extract. the protection studies showed that the 22.9-kda pr ... | 2000 | 10670567 |
| the brucella abortus lon functions as a generalized stress response protease and is required for wild-type virulence in balb/c mice. | the gene encoding a lon protease homologue has been cloned from brucella abortus. the putative brucella abortus lon shares > 60% amino acid identity with its escherichia coli counterpart and the recombinant form of this protein restores the capacity of an escherichia coli lon mutant to resist killing by ultraviolet irradiation and regulate the expression of a cpsb:lacz fusion to wild-type levels. a sigma32 type promoter was identified upstream of the predicted lon coding region and northern anal ... | 2000 | 10672180 |
| lung-tissue extract as an alternative to serum for surveillance for brucellosis in chamois. | serological surveys are the most-used way to study diseases in free-ranging wild animals. however, the difficulty in obtaining a sufficient number of suitable serum samples is a major problem. to resolve this problem, we investigated the possibility of using lung-tissue extract in place of blood serum for searching for antibodies against brucella abortus. antibodies titres against b. abortus was tested from blood serum and lung-tissue extract from 112 chamois and 99 cattle. although in complemen ... | 2000 | 10673058 |
| identification of brucella suis genes affecting intracellular survival in an in vitro human macrophage infection model by signature-tagged transposon mutagenesis. | bacteria of the genus brucella are facultative intracellular pathogens which have developed the capacity to survive and multiply in professional and nonprofessional phagocytes. the genetic basis of this aspect of brucella virulence is still poorly understood. to identify new virulence factors, we have adapted signature-tagged transposon mutagenesis, which has been used essentially in animal models, to an in vitro human macrophage infection model. a library of 1,152 brucella suis 1330 tagged mini ... | 2000 | 10678941 |
| genetic resistance to experimental infection with mycobacterium bovis in red deer (cervus elaphus). | tuberculosis (tb) caused by mycobacterium bovis is a worldwide threat to livestock and humans. one control strategy is to breed livestock that are more resistant to mycobacterium bovis. in a 3-year heritability study 6 farmed red deer stags were selected from 39 on the basis of their differing responses to experimental challenge via the tonsillar sac with approximately 500 cfu of m. bovis. two stags remained uninfected, two were moderately affected, and two developed serious spreading tb. sevent ... | 2000 | 10678981 |
| lipopolysaccharides of brucella abortus and brucella melitensis induce nitric oxide synthesis in rat peritoneal macrophages. | smooth lipopolysaccharide (s-lps) and lipid a of brucella abortus and brucella melitensis induced the production of nitric oxide (no) by rat adherent peritoneal cells, but they induced lower levels of production of no than escherichia coli lps. the participation of the inducible isoform of no synthase (inos) was confirmed by the finding of an increased expression of both inos mrna and inos protein. these observations might help to explain (i) the acute outcome of brucella infection in rodents, ( ... | 2000 | 10679001 |
| expression of ykda, encoding a bacillus subtilis homologue of htra, is heat shock inducible and negatively autoregulated. | there are three members of the htra family of serine proteases, ykda, yvta, and yyxa, encoded in the chromosome of bacillus subtilis. in this study, we report on the promoter structure and regulation of ykda expression. the ykda gene is heat inducible, exhibiting a biphasic pattern of expression during a 60-min interval after heat shock. increased expression after heat shock occurs at the transcriptional level. the heat-shock-inducible promoter has a single mismatch with a siga-type -10 motif, b ... | 2000 | 10692364 |
| topology prediction of brucella abortus omp2b and omp2a porins after critical assessment of transmembrane beta strands prediction by several secondary structure prediction methods. | in order to propose a reliable model for brucella porin topology, several structure prediction methods were evaluated in their ability to predict porin topology. four porins of known structure were selected as test-cases and their secondary structure delineated. the specificity and sensitivity of 11 methods were separately evaluated. our critical assessment shows that some secondary structure prediction methods (phd, dsc, sopma) originally designed to predict globular protein structure are usefu ... | 2000 | 10698111 |
| molecular characterization of brucella strains isolated from marine mammals. | recently, gram-negative bacteria isolated from a variety of marine mammals have been identified as brucella species by conventional phenotypic analysis. this study found the 16s rrna gene from one representative isolate was identical to the homologous sequences of brucella abortus, b. melitensis, b. canis, and b. suis. is711-based dna fingerprinting of 23 isolates from marine mammals showed all the isolates differed from the classical brucella species. in general, fingerprint patterns grouped by ... | 2000 | 10699036 |
| the genes for erythritol catabolism are organized as an inducible operon in brucella abortus. | erythritol utilization is a characteristic of pathogenic brucella abortus strains. the attenuated vaccine strain b19 is the only brucella strain that is inhibited by erythritol, so a role for erythritol metabolism in virulence is suspected. a chromosomal fragment from the pathogenic strain b. abortus 2308 containing genes for the utilization of erythritol was cloned taking advantage of an erythritol-sensitive tn5 insertion mutant. the nucleotide sequence of the complete 7714 bp fragment was dete ... | 2000 | 10708387 |
| purification and characterization of the deor repressor of bacillus subtilis. | transcription of the bacillus subtilis dra-nupc-pdp operon is repressed by the deor repressor protein. the deor repressor with an n-terminal his tag was overproduced with a plasmid under control of a phage t5 promoter in escherichia coli and was purified to near homogeneity by one affinity chromatography step. gel filtration experimental results showed that native deor has a mass of 280 kda and appears to exist as an octamer. binding of deor to the operator dna of the dra-nupc-pdp operon was cha ... | 2000 | 10714997 |
| antibody-mediated elimination of the obligate intracellular bacterial pathogen ehrlichia chaffeensis during active infection. | it is generally accepted that cellular, but not humoral immunity, plays an important role in host defense against intracellular bacteria. however, studies of some of these pathogens have provided evidence that antibodies can provide immunity if present during the initiation of infection. here, we examined immunity against infection by ehrlichia chaffeensis, an obligate intracellular bacterium that causes human monocytic ehrlichiosis. studies with mice have demonstrated that immunocompetent strai ... | 2000 | 10722619 |
| roles of interleukin-12 and gamma interferon in murine chlamydia pneumoniae infection. | balb/c and strain 129 mice infected intranasally with chlamydia pneumoniae displayed a moderate-to-severe inflammation in the lungs and produced interleukin-12 (il-12), gamma interferon (ifn-gamma), tumor necrosis factor alpha (tnf-alpha), and il-10, with peak levels on days 1 to 3 postinfection (p.i.), returning to basal levels by day 16 p.i. anti-il-12 treatment resulted in less-severe pathological changes but higher bacterial titers on days 3 and 7 p.i. by day 16 p.i., the inflammatory respon ... | 2000 | 10722626 |
| selective media for isolation of brucella abortus strain rb51. | brucella abortus strain rb51 (srb51) is the standard vaccine used to protect cattle against brucellosis and is currently being used to vaccinate bison in the united states (us). currently available media for culture of brucella have not been evaluated for their ability to support growth of srb51. in this study, five selective media for isolating brucellae, four commercially available media for gram-negative bacteria, and tryptose agar with 5% bovine serum (tsa) were compared to two srb51 selecti ... | 2000 | 10731617 |
| similar requirements of a plant symbiont and a mammalian pathogen for prolonged intracellular survival. | brucella abortus, a mammalian pathogen, and rhizobium meliloti, a phylogenetically related plant symbiont, establish chronic infections in their respective hosts. here a highly conserved b. abortus homolog of the r. meliloti baca gene, which encodes a putative cytoplasmic membrane transport protein required for symbiosis, was identified. an isogenic b. abortus baca mutant exhibited decreased survival in macrophages and greatly accelerated clearance from experimentally infected mice compared to t ... | 2000 | 10741969 |
| the ++sinorhizobium meliloti lon protease is involved in regulating exopolysaccharide synthesis and is required for nodulation of alfalfa. | while screening for sinorhizobium meliloti pho regulatory mutants, a transposon mutant was isolated that constitutively expressed higher levels of acid and alkaline phosphatase enzymes. this mutant was also found to form pseudonodules on alfalfa that were delayed in appearance relative to those formed by the wild-type strain, it contained few bacteroids, and it did not fix nitrogen. sequence analysis of the transposon insertion site revealed the affected gene to have high homology to lon proteas ... | 2000 | 10762258 |
| divergence in macromolecular assembly: x-ray crystallographic structure analysis of lumazine synthase from brucella abortus. | we have determined the three-dimensional structure of 6, 7-dimethyl-8-ribityllumazine synthase (lumazine synthase) from brucella abortus, the infectious organism of the disease brucellosis in animals. this enzyme catalyses the formation of 6, 7-dimethyl-8-ribityllumazine, the penultimate product in the synthesis of riboflavin. the three-dimensional x-ray crystal structure of the enzyme from b. abortus has been solved and refined at 2.7 a resolution to a final r-value of 0.18 (r(free)=0.23). the ... | 2000 | 10764570 |
| the gale gene of campylobacter jejuni is involved in lipopolysaccharide synthesis and virulence. | lipopolysaccharide (lps) is one of the main virulence factors of gram-negative bacteria. the lps from campylobacter spp. has endotoxic properties and has been shown to play a role in adhesion. we previously cloned a gene cluster (wla) which is involved in the synthesis of the campylobacter jejuni 81116 lps molecule. sequence alignment of the first gene in this cluster indicated similarity with gale genes. these genes encode a udp-glucose 4-epimerase, which catalyzes the interconversion of udp-ga ... | 2000 | 10768949 |
| characterization of heat, oxidative, and acid stress responses in brucella melitensis. | brucella melitensis is a facultative intracellular pathogen which is able to survive and replicate within phagocytic cells. therefore, it has to adapt to a range of different hostile environments. in order to understand the mechanisms of intracellular survival employed by virulent b. melitensis 16m, an initial approach consisting of analysis of the differences in patterns of protein synthesis in response to heat, oxidative, and acid ph stresses by two-dimensional (2-d) polyacrylamide gel electro ... | 2000 | 10768994 |
| identification of genes encoding exported mycobacterium tuberculosis proteins using a tn552'phoa in vitro transposition system. | secreted and cell envelope-associated proteins are important to both mycobacterium tuberculosis pathogenesis and the generation of protective immunity to m. tuberculosis. we used an in vitro tn552'phoa transposition system to identify exported proteins of m. tuberculosis. the system is simple and efficient, and the transposon inserts randomly into target dna. m. tuberculosis genomic libraries were targeted with tn552'phoa transposons, and these libraries were screened in m. smegmatis for active ... | 2000 | 10781540 |
| antimicrobial peptides protect coho salmon from vibrio anguillarum infections. | fish losses from infectious diseases are a significant problem in aquaculture worldwide. therefore, we investigated the ability of cationic antimicrobial peptides to protect against infection caused by the fish pathogen vibrio anguillarum. to identify effective peptides for fish, the mics of certain antimicrobial peptides against fish pathogens were determined in vitro. two of the most effective antimicrobial peptides, ceme, a cecropin-melittin hybrid peptide, and pleurocidin amide, a c-terminal ... | 2000 | 10788362 |
| development of a fluorescence polarization-based diagnostic assay for equine infectious anemia virus. | the control of equine infectious anemia virus (eiav) infections of horses has been over the past 20 years based primarily on the identification and elimination of seropositive horses, predominantly by a standardized agar gel immunodiffusion (agid) assay in centralized reference laboratories. this screening for eiav-seropositive horses has been to date hindered by the lack of a rapid diagnostic format that can be easily employed in the field. we describe here the development of a rapid solution-p ... | 2000 | 10790112 |
| brucella abortus infection acquired in microbiology laboratories. | we report an outbreak of laboratory-acquired brucella abortus infection originating in the accidental breakage of a centrifuge tube. a total of 12 laboratory workers were infected (attack rate of 31%), with an incubation time ranging from 6 weeks to 5 months. antibody titers were evaluated weekly in all personnel exposed, allowing the diagnosis of the infection in most cases before the onset of clinical symptoms, so that specific therapy could be administrated. | 2000 | 10790142 |
| antibody repertoire development in fetal and newborn piglets, iii. colonization of the gastrointestinal tract selectively diversifies the preimmune repertoire in mucosal lymphoid tissues. | changes in the vh-region repertoire of isolator piglets reared for 6 weeks under germ-free (gf) conditions and those colonized (col) with a defined exclusion flora on the 1st day of life were compared. although serum immunoglobulin levels were 20-100-fold higher in col piglets than gf piglets, an analysis of peripheral blood b cells (pbbs) indicated that: gf and col piglets used the same four vh genes and two dh segments during the 6-week period; proportional usage of vh genes and dh segments wa ... | 2000 | 10809967 |
| serosurvey for selected infectious disease agents in free-ranging black and white rhinoceros in africa. | two hundred and eighty one serum samples collected from free-ranging black (diceros bicornis) and white (ceratotherium simum) rhinoceros, in the republic of south africa (rsa), namibia, and kenya from 1987-97, were examined for antibody to 16 different infectious agents. positive antibody titers were detected against akabane (59.8%), bluetongue (55%), african horse sickness (27.9%), epizootic haemorrhagic disease of deer (19.4%), parainfluenza type 3 (25.3%), bovine herpes virus 1 (3.1%), equine ... | 2000 | 10813614 |
| brucella abortus and its closest phylogenetic relative, ochrobactrum spp., differ in outer membrane permeability and cationic peptide resistance. | the outer membrane (om) of the intracellular parasite brucella abortus is permeable to hydrophobic probes and resistant to destabilization by polycationic peptides and edta. the significance of these unusual properties was investigated in a comparative study with the opportunistic pathogens of the genus ochrobactrum, the closest known brucella relative. ochrobactrum spp. oms were impermeable to hydrophobic probes and sensitive to polymyxin b but resistant to edta. these properties were traced to ... | 2000 | 10816465 |
| overexpression of protective antigen as a novel approach to enhance vaccine efficacy of brucella abortus strain rb51. | brucella abortus strain rb51 is an attenuated rough strain that is currently being used as the official live vaccine for bovine brucellosis in the united states and several other countries. we reasoned that overexpression of a protective antigen(s) of b. abortus in strain rb51 should enhance its vaccine efficacy. to test this hypothesis, we overexpressed cu/zn superoxide dismutase (sod) protein of b. abortus in strain rb51. this was accomplished by transforming strain rb51 with a broad-host-rang ... | 2000 | 10816475 |
| brucella abortus strain rb51 as a vector for heterologous protein expression and induction of specific th1 type immune responses. | brucella abortus strain rb51 is a stable, rough, attenuated mutant widely used as a live vaccine for bovine brucellosis. our ultimate goal is to develop strain rb51 as a preferential vector for the delivery of protective antigens of other intracellular pathogens to which the induction of a strong th1 type of immune response is needed for effective protection. as a first step in that direction, we studied the expression of a foreign reporter protein, beta-galactosidase of escherichia coli, and th ... | 2000 | 10816476 |
| use of brucella abortus vaccine strain rb51 in pregnant cows after calfhood vaccination with strain 19 in argentina. | one hundred and seven pregnant cows, which had been calfhood vaccinated with brucella abortus strain 19 (s-19) were revaccinated with either s-19 or strain rb51 (s-rb51). all s-19-revaccinated animals seroconverted, while none of the rb51-revaccinated animals seroconverted. two out of 25 (8%) s-19-revaccinated animals aborted, while none of the 57 rb51-revaccinated group aborted. four of the s-19-revaccinated animals shed s-19 in the milk for at least 7 days, while only 1 cow shed s-rb51 for at ... | 2000 | 10821960 |
| prostaglandin e(2) increases bovine leukemia virus tax and pol mrna levels via cyclooxygenase 2: regulation by interleukin-2, interleukin-10, and bovine leukemia virus. | prostaglandin e(2) (pge(2)), produced by macrophages, has important immune regulatory functions, suppressing a type 1 immune response and stimulating a type 2 immune response. type 1 cytokines (interleukin-2 [il-2], il-12, and gamma interferon) increase in freshly isolated peripheral blood mononuclear cells (pbmcs) of animals with an early disease stage of bovine leukemia virus (blv) infection, while il-10 increases in animals with a late disease stage. although il-10 has an immunosuppressive ro ... | 2000 | 10823885 |
| effect of vaccination with brucella abortus strain rb51 on heifers and pregnant cattle. | thirteen cows, which had been vaccinated as calves with strain 19, were revaccinated twice or three times as adults with i x 109 cfu of b. abortus strain rb51. their serological responses following adult vaccination remained negative to conventional brucellosis surveillance tests. vaccination with strain rb51 during the eighth month of pregnancy did not induce abortion, although strain rb51 was recovered from milk for up to 69 days after vaccination. in a parallel study, thirteen 8- to 10-month- ... | 2000 | 10836273 |
| the brucella abortus ccrm dna methyltransferase is essential for viability, and its overexpression attenuates intracellular replication in murine macrophages. | the ccrm dna methyltransferase of the alpha-proteobacteria catalyzes the methylation of the adenine in the sequence gantc. like dam in the enterobacteria, ccrm plays a regulatory role in caulobacter crescentus and rhizobium meliloti. ccrm is essential for viability in both of these organisms, and we show here that it is also essential in brucella abortus. further, increased copy number of the ccrm gene results in striking changes in b. abortus morphology, dna replication, and growth in murine ma ... | 2000 | 10852881 |
| transferred dna (t-dna)-associated proteins of agrobacterium tumefaciens are exported independently of virb. | the transfer of t-dna from agrobacterium to plant cells is mediated by a system which involves the virb operon of the ti plasmid. we report that vire2 and vird2, two t-dna-associated proteins, as well as virf, a protein known to be secreted into plant cells, are present in the periplasm and supernatant fractions of growing cells of agrobacterium as are virj and chve, two known periplasmic proteins. two cytoplasmic proteins, ros and chloramphenicol acetyl transferase, and a vire2green fluorescent ... | 2000 | 10852952 |
| seroepidemiology of brucella abortus infection in bovids in sri lanka. | from 1992 to 1995, 0.15% (n=3916) of the bovids (cattle and buffalo) in sri lanka were sampled, using a multi-stage sampling procedure. serum antibodies for brucella abortus were detected using the indirect enzyme-linked immunosorbent assay (elisa). the age, the agroecological zone and the management system practiced in the farms of the sampled bovids were studied as risk factors for seropositivity. the overall seroprevalence of brucellosis in cattle was 4.7% (n=3076) and 4.2% in buffaloes (n=84 ... | 2000 | 10854935 |
| regulation of brucella abortus catalase. | all aerobic organisms have mechanisms that protect against oxidative compounds. catalase, peroxidase, superoxide dismutase, glutathione, and thioredoxin are widely distributed in many taxa and constitute elements of a nearly ubiquitous antioxidant metabolic strategy. interestingly, the regulatory mechanisms that control these elements are rather different depending on the nature of the oxidative stress and the organism. catalase is well documented to play an important role in protecting cells fr ... | 2000 | 10858195 |
| complementation of brucella abortus rb51 with a functional wboa gene results in o-antigen synthesis and enhanced vaccine efficacy but no change in rough phenotype and attenuation. | brucella abortus rb51 is a stable rough, attenuated mutant vaccine strain derived from the virulent strain 2308. recently, we demonstrated that the wboa gene in rb51 is disrupted by an is711 element (r. vemulapalli, j. r. mcquiston, g. g. schurig, n. srirauganathan, s. m. halling, and s. m. boyle, clin. diagn. lab. immunol. 6:760-764, 1999). disruption of the wboa gene in smooth, virulent b. abortus, brucella melitensis, and brucella suis results in rough, attenuated mutants which fail to produc ... | 2000 | 10858205 |
| molecular cloning and expression of cu/zn-containing superoxide dismutase from fasciola hepatica. | the cytosolic superoxide dismutase (sod) of fasciola hepatica, a causative agent of fascioliasis, was purified and characterized. the enzyme consists of two identical subunits, each with an apparent molecular mass of 17.5 kda. an analysis of the enzyme's primary structure and inhibition studies revealed that the enzyme is a copper/zinc-containing sod (cu/zn-sod). the enzyme activity was relatively stable in a broad ph range, from ph 7.0 to 10.0, and the enzyme showed maximum activity at ph 7.5. ... | 2000 | 10858207 |
| identification of genes required for chronic persistence of brucella abortus in mice. | the genetic basis for chronic persistence of brucella abortus in lymphoid organs of mice, cows, and humans is currently unknown. we identified b. abortus genes involved in chronic infection, by assessing the ability of 178 signature-tagged mutants to establish and maintain persistent infection in mice. each mutant was screened for its ability to colonize the spleens of mice at 2 and 8 weeks after inoculation. comparison of the results from both time points identified two groups of mutants attenu ... | 2000 | 10858227 |
| intracellular trafficking of brucella abortus in j774 macrophages. | brucella abortus is a facultative intracellular bacterium capable of surviving inside professional and nonprofessional phagocytes. the microorganism remains in membrane-bound compartments that in several cell types resemble modified endoplasmic reticulum structures. to monitor the intracellular transport of b. abortus in macrophages, the kinetics of fusion of phagosomes with preformed lysosomes labeled with colloidal gold particles was observed by electron microscopy. the results indicated that ... | 2000 | 10858243 |
| host resistance to listeria monocytogenes infection is enhanced but resistance to staphylococcus aureus infection is reduced in acute graft-versus-host disease in mice. | acute graft-versus-host disease (gvhd) is characterized by the production of high levels of t helper 1 (th1)-type cytokines. bone marrow transplantation from allogeneic c57bl/6 cells to cbf(1) mice produced acute gvhd. host resistance to th1-driven listeria monocytogenes was enhanced, whereas host resistance to th2-driven staphylococcus aureus was reduced during acute gvhd. these results suggest that opposite host responses are observed between th1-driven and th2-driven bacterial infections in a ... | 2000 | 10858256 |
| use of polymerase chain reaction to detect brucella abortus biovar 1 in infected goats. | the polymerase chain reaction (pcr) was used to diagnose goat brucellosis and compare its sensitivity against some of the most commonly used serological and bacteriological techniques. twenty two female and one male out of 300 clinically healthy, mixed-breed goats were randomly chosen from a ranch located at marín, nuevo león, mexico. milk and blood samples were taken from each animal and used to obtain both microbiological cultures and dna of the pathogen, and sera was tested against rose benga ... | 2000 | 10865155 |
| antibody responses to sheep red blood cell and brucella abortus antigens in a turkey line selected for increased body weight and its randombred control. | turkeys from a randombred control line (rbc2) and its subline (f) selected for increased 16-wk bw were tested for primary and secondary antibody responses to srbc antigen and brucella abortus antigen (ba). previous studies have shown that the f line was more susceptible to pasteurella multocida and newcastle disease virus than was the rbc2 line. individuals from the rbc2 and f lines were intravenously injected with 1 ml 5% srbc antigen or 0.1 ml undiluted ba at 4 and 6 wk of age; blood samples w ... | 2000 | 10875759 |
| a multiplex approach to molecular detection of brucella abortus and/or mycobacterium bovis infection in cattle. | a multiplex amplification and detection platform for the diagnosis of mycobacterium bovis and brucella abortus infection simultaneously in bovine milk and nasal secretions was developed. this system (designated the bovine pathogen detection assay [bpda]-pcr) consists of duplex amplification of species-specific targets (a region of the bcsp31k gene of b. abortus and a repeat-sequence region in the hsp65 gene of m. bovis, respectively). this is followed by a solid-phase probe capture hybridization ... | 2000 | 10878051 |
| fluorescent whole-cell hybridization with 16s rrna-targeted oligonucleotide probes to identify brucella spp. by flow cytometry. | a whole-cell hybridization assay with fluorescent oligonucleotide probes derived from the 16s rrna sequence of brucella abortus in combination with flow cytometry has been developed. with the three fluorescent probes selected, a positive signal was observed with all the representative strains of the species and biovars of brucella and with a total of nine different brucella clinical isolates. using the b9 probe in the hybridization assay, it was possible to discriminate between brucella suis bio ... | 2000 | 10878084 |
| osmotic regulation of cyclic 1,2-beta-glucan synthesis. | in contrast to what happens in agrobacterium: tumefaciens and rhizobium: meliloti, synthesis of periplasmic cyclic 1,2-beta-glucan in brucella: spp. was not inhibited when bacteria were grown in media of high osmolarity. studies performed with crude membrane preparations showed that cyclic 1,2-beta-glucan synthetase of brucella: spp. was not inhibited by 0.5 m kcl or potassium glutamate; concentrations that completely inhibit the osmosensitive enzymes of a. tumefaciens a348 or r. meliloti 102f34 ... | 2000 | 10878137 |
| structural, functional and immunological studies on a polymeric bacterial protein. | the characterization of proteins from brucella spp, the causative agent of brucellosis, has been the subject of intensive research. we have described an 18-kda cytoplasmic protein of brucella abortus and shown the potential usefulness of this protein as an antigen for the serologic diagnosis of brucellosis. the amino acid sequence of the protein showed a low but significant homology with that of lumazine synthases. lumazine is an intermediate product in bacterial riboflavin biosynthesis. the rec ... | 2000 | 10881048 |
| in vitro markers and biological activity in mice of seed lot strains and commercial brucella melitensis rev 1 and brucella abortus b19 vaccines. | four seed lots and fourteen batches of brucella melitensis rev 1 and b. abortus b19 living anti-brucella commercial vaccines obtained from six spanish laboratories were tested in vitro and in vivo in the reference mouse model for quality control. all the strains tested showed the characteristic morphology of their respective rev 1 or b19 reference strains with the exception of three rev 1 strains: seed lot sl2 and commercial vaccine r3, in which giant colonies were predominant, and commercial va ... | 2000 | 10885618 |
| bartonella infection in animals: carriership, reservoir potential, pathogenicity, and zoonotic potential for human infection. | recent observations have begun to support a role for bartonella spp. as animal as well as human pathogens. bartonella spp. are vector-transmitted, blood-borne, intracellular, gram-negative bacteria that can induce prolonged infection in the host. persistent infections in domestic and wild animals result in a substantial reservoir of bartonella organisms in nature that can serve as a source for inadvertent human infection. the prevalence of bacteremia can range from 50 to 95% in selected rodent, ... | 2000 | 10885985 |
| activation of human vgamma9vdelta2 t cells by a brucella suis non-peptidic fraction impairs bacterial intracellular multiplication in monocytic infected cells. | human gamma delta t cells are considered to play an important role in the early response to infection with intracellular pathogens. evidence has been presented that the percentage of gamma delta t cells with vgamma9vdelta2 phenotype is dramatically increased in the peripheral blood of patients with acute brucellosis. this specific gd t-cell subpopulation is known to be activated by small non-peptidic molecules that can either be produced by the pathogen itself or released from damaged cells afte ... | 2000 | 10886403 |
| ccr8 on human thymocytes functions as a human immunodeficiency virus type 1 coreceptor. | to determine whether human immunodeficiency virus type 1 (hiv-1) coreceptors besides cxcr4 and ccr5 are involved in hiv-1 infection of the thymus, we focused on ccr8, a receptor for the chemokine i-309, because of its high expression in the thymus. similar levels of ccr8 mrna were detected in immature and mature primary human thymocytes. consistent with this, [(125)i]i-309 was shown to bind specifically and with similar affinity to the surface of immature and mature human thymocytes. fusion of h ... | 2000 | 10888633 |
| cloning and kinetics of expression of brucella abortus heat shock proteins by baculovirus recombinants. | in an effort to develop genetically engineered brucella abortus (ba) vaccines, the genes encoding heat shock proteins (hsps) groel, groes, and htra were cloned and expressed in the bac-to-bac baculovirus system, and the kinetics of protein expression were analyzed using various insect cell lines in suspension cultures, different cell densities in suspension cultures, multiplicities of infection and recombinant virus replication times. trichoplusia ni cells expressed only ba htra, but spodoptera ... | 2000 | 10889410 |
| interleukin-10 has different effects on proliferation of listeria monocytogenes in livers and spleens of mice. | the aim of this study was to investigate the effect of interleukin-10 (il-10) on the course of listeria monocytogenes infection in naive and immune mice. treatment with il-10 during the course of a primary infection significantly decreased the number of bacteria in the spleen and did not affect the number in the liver. during a secondary infection in immune mice treated with il-10, the number of bacteria was significantly lower in the spleen but significantly higher in the liver in comparison to ... | 2000 | 10899871 |
| [cu,zn]-superoxide dismutase mutants of the swine pathogen actinobacillus pleuropneumoniae are unattenuated in infections of the natural host. | actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia, contains a periplasmic cu- and zn-cofactored superoxide dismutase ([cu,zn]-sod, or sodc) which has the potential, realized in other pathogens, to promote bacterial survival during infection by dismutating host-defense-derived superoxide. here we describe the construction of a site-specific, [cu,zn]-sod-deficient a. pleuropneumoniae serotype 1 mutant and show that although the mutant is highly sensitive to the microb ... | 2000 | 10899887 |
| isolation, sequencing and expression of bartonella henselae omp43 and predicted membrane topology of the deduced protein. | the infection of and interaction of human endothelial cells with bartonella henselae is one of the most interesting aspects of bartonella -associated disease. the gene encoding the 43 kda b. henselae outer membrane protein (omp43) that binds endothelial cells was cloned and sequenced. sequence analysis revealed an open reading frame of 1206 nucleotides coding for a protein of 402 amino acids. analysis of the deduced amino acid sequence shows 38% identity over the entire sequence to the brucella ... | 2000 | 10906262 |
| investigations on the prevalence of bovine tuberculosis and brucellosis in dairy cattle in dar es salaam region and in zebu cattle in lugoba area, tanzania. | a study between august 1995 and december 1997 included 343 dairy cattle on 20 farms in the dar es salaam region and 2289 zebu cattle on 39 bomas in the lugoba area (coast region). the aim was to establish the prevalence of bovine tuberculosis (mycobacterium bovis) and bovine brucellosis (brucella abortus). in the single intradermal tuberculin test (sit), 0.9% (3/343) of the animals in dar es salaam tested positive and 1.2% (4/343) were doubtful. positive reactors were found in 10% (2/20) of the ... | 2000 | 10907285 |
| treatment of supraspinous bursitis by use of debridement in standing horses: 10 cases (1968-1999). | to evaluate efficacy of debridement for treatment of supraspinous bursitis in horses and to evaluate the outcome. | 2000 | 10909451 |
| [brucellosis in pregnancy]. | brucellosis is rare in pregnancy. recently, an increase in the incidence of this disease has been observed in our area. we present 7 cases of brucellosis in pregnancy and review the literature on the effects of brucellosis on the outcome of pregnancy. brucellosis is rare in the middle east and africa and the most common source of infection is unpasteurized milk products. brucella is a coccobacillus, gram-negative bacterium, whose hosts are mostly animals. there is controversy about the relations ... | 1998 | 10909521 |
| seroprevalence of brucellosis in cattle and humans in the akwapim-south district of ghana: public health implications. | a total of 183 cattle comprising 54 bulls, 53 milking cows, 76 heifers and 44 calves in the akwapim-south district of ghana were tested for antibodies against brucella abortus using the rose bengal plate test. the results indicated that cattle in the akwapim-south district were infected with brucella with a mean seroprevalence of 6. 6%. there was no difference in the seroprevalence either between females 11/129 (8.5%) and males 1/54 (1.9%), or among the three different breeds of cattle (sanga, w ... | 2000 | 10913765 |
| [history of the eradication of bovine brucellosis in the czech republic]. | in the czech republic, the program of recovery of the livestock from brucellosis caused by the micro-organisms brucella abortus was successfully completed in 1964. the campaign started in 1959 by the exploration of the complete cattle population by agglutination tests. incidence of the disease was 211 positive cases for each 100 thousands, prevalence was 0.676% (20,481 animal in 654 foci of 34 districts). the prevalence was significantly higher in large cattle units. tens of new cases of the hum ... | 2000 | 10916210 |
| brucellosis transmitted by bone marrow transplantation. | we report a unique case of brucellosis transmitted by bmt. an 8-year-old boy with the diagnosis of fanconi's anemia received an allogeneic bmt from his hla-identical sibling. routine culture from the infused marrow suspension grew brucella abortus on day +4 post bmt. spiking fevers occurred on days +2 and +16. the first febrile episode responded to broad-spectrum antibiotic therapy. however, the second episode did not. b. abortus was isolated from blood cultures taken during the second febrile e ... | 2000 | 10918436 |
| characterization of bartonella clarridgeiae flagellin (flaa) and detection of antiflagellin antibodies in patients with lymphadenopathy. | cat scratch disease (csd) is a frequent clinical outcome of bartonella henselae infection in humans. recently, two case reports indicated bartonella clarridgeiae as an additional causative agent of csd. both pathogens have been isolated from domestic cats, which are considered to be their natural reservoir. b. clarridgeiae and b. henselae can be distinguished phenotypically by the presence or absence of flagella, respectively. separation of the protein content of purified flagella of b. clarridg ... | 2000 | 10921956 |
| validation of the abbreviated brucella amos pcr as a rapid screening method for differentiation of brucella abortus field strain isolates and the vaccine strains, 19 and rb51. | the brucella amos pcr assay was previously developed to identify and differentiate specific brucella species. in this study, an abbreviated brucella amos pcr test was evaluated to determine its accuracy in differentiating brucella abortus into three categories: field strains, vaccine strain 19 (s19), and vaccine strain rb51/parent strain 2308 (s2308). two hundred thirty-one isolates were identified and tested by the conventional biochemical tests and brucella amos pcr. this included 120 isolates ... | 2000 | 10921983 |
| attenuation and immunogenicity of a brucella abortus htra cycl double mutant in cattle. | phe1 is a htra cycl double gene deletion mutant of virulent brucella abortus strain 2308 (s2308) which has previously been evaluated in the murine and caprine models of bovine brucellosis. this report describes the results of studies conducted with this mutant in the natural bovine host. six sexually mature, non-gravid heifers were inoculated via the conjunctival sac with 1 x 10(10) colony forming units (cfu) of either the parental s2308 or the htra cycl gene deletion mutant, phe1. at 4, 7 and 1 ... | 2000 | 10925044 |
| growth of brucella abortus in macrophages from resistant and susceptible mouse strains. | c57bl/10 mice have a superior ability to control chronic infections with virulent strains of the intracellular bacteria brucella abortus compared with balb/c mice. while a number of differences in the cytokines produced by lymphocytes following infection of these two strains of mice have been shown, macrophages have not been evaluated for their role in conveying relative resistance. the importance of macrophages in control of brucella infections is demonstrated by the observations that intracell ... | 2000 | 10931144 |
| hsp and apoptosis in leukocytes from infected or vaccinated animals by brucella abortus. | the production of hsp and apoptosis of leukocytes in the peripheral blood of animals naturally infected with brucella spp or treated with the vaccine brucella abortus 19 have been investigated in this study. cytokines able to induce phagocytic activity in macrophages of non treated healthy animals were found in the supernatant of bovine leukocytes cultivated in vitro. a long-lasting antibody response against hsp 60 kda and 27 kda, which lasts a long time, is induced in naturally infected animals ... | 2000 | 10939042 |
| mutations in each of the tol genes of pseudomonas putida reveal that they are critical for maintenance of outer membrane stability. | the outer membrane of gram-negative bacteria functions as a permeability barrier that protects cells against a large number of antibacterial agents. oprl protein of pseudomonas putida has been shown to be crucial to maintain the stability of this cell component (j. j. rodríguez-herva, m.-i. ramos-gonzález, and j. l. ramos. j. bacteriol. 178:1699-1706, 1996). in the present study we cloned and mutagenized the orf1, tolq, tolr, tola, and tolb genes from p. putida kt2440, which were located upstrea ... | 2000 | 10940016 |
| a homologue of an operon required for dna transfer in agrobacterium is required in brucella abortus for virulence and intracellular multiplication. | as part of a brucella abortus 2308 genome project carried out in our laboratory, we identified, cloned, and sequenced a genomic dna fragment containing a locus (virb) highly homologous to bacterial type iv secretion systems. the b. abortus virb locus is a collinear arrangement of 13 open reading frames (orfs). between virb1 and virb2 and downstream of orf12, two degenerated, palindromic repeat sequences characteristic of brucella intergenic regions were found. gene reporter studies demonstrated ... | 2000 | 10940027 |
| validation of the fluorescence polarization assay and comparison to other serological assays for the detection of serum antibodies to brucella abortus in bison. | a number of serological tests were compared for the detection of antibodies to brucella abortus in bison (bison bison). the performance of the fluorescence polarization assay (fpa) in both the preliminary evaluation and a subsequent blind validation indicated that this test was the most suitable for serological diagnosis of brucellosis in bison. the sensitivity and specificity in the preliminary evaluation were 92.1% and 99.4%, respectively. the sensitivity and specificity in a subsequent blind ... | 2000 | 10941731 |
| safety and efficacy of brucella abortus strain rb51 vaccine in captive pregnant elk. | brucella abortus strain rb51 is a laboratory-derived rough mutant of virulent b. abortus strain 2308 used as a vaccine because it induces antibodies that do not react on standard brucellosis serologic tests. strain rb51 vaccine was evaluated in pregnant captive elk (cervus elaphus) to determine (1) if it induced abortion and (2) if it protected against abortion following subsequent challenge. the time period of this study (february-june, 1998) was similar to field conditions where elk are vaccin ... | 2000 | 10941732 |
| safety of brucella abortus strain rb51 in bull elk. | some of the elk (cervus elaphus nelsoni) of the greater yellowstone area (wyoming, idaho, montana; usa) are infected with brucella abortus, the bacterium that causes bovine brucellosis. brucella abortus strain rb51 vaccine is being considered as a means to control b. abortus induced abortions in cow elk. however, the most probable vaccination strategies for use in free-ranging elk might also result in some bull elk being inoculated, thus, it is important to insure that the vaccine is safe in the ... | 2000 | 10941733 |
| structure and properties of the outer membranes of brucella abortus and brucella melitensis. | the brucellae are gram-negative bacteria characteristically able to multiply facultatively within phagocytic cells and which cause a zoonosis of world-wide importance. this article reviews the structure and topology of the main components (lipopolysaccharide, native hapten polysaccharide, free lipids and proteins) of the outer membranes of brucella abortus and b. melitensis, as well as some distinctive properties (permeability and interactions with cationic peptides) of these membranes. on these ... | 1998 | 10943337 |
| humoral immune response of balb/c mice to a vaccinia virus recombinant expressing brucella abortus groel does not correlate with protection against a b. abortus challenge. | this work is a part of an ongoing effort to develop vaccinia virus recombinants expressing various brucella abortus proteins. the b. abortus groel gene encoding the antigenic heat shock protein groel was subcloned into vaccinia virus via homologous recombination and expression confirmed by western blotting. female balb/c mice inoculated with recombinant vaccinia virus/groel produced groel and vaccinia virus specific antibodies. mice were challenged 8 weeks post-inoculation with virulent b. abort ... | 2000 | 10946149 |
| aggregation substance promotes adherence, phagocytosis, and intracellular survival of enterococcus faecalis within human macrophages and suppresses respiratory burst. | the aggregation substance (as) of enterococcus faecalis, encoded on sex pheromone plasmids, is a surface-bound glycoprotein that mediates aggregation between bacteria thereby facilitating plasmid transfer. sequencing of the pad1-encoded asa1 revealed that this surface protein contains two rgd motifs which are known to ligate integrins. therefore, we investigated the influence of as on the interaction of e. faecalis with human monocyte-derived macrophages which constitutively express beta(2) inte ... | 2000 | 10948103 |
| role of ribosomal protein l12 in gonococcal invasion of hec1b cells. | previous studies led to the development of a model of contact-induced enhanced gonococcal invasion of human reproductive cells that utilizes the lutropin receptor (lhr) as both the induction signal for conversion to this enhanced-gonococcal-invasion phenotype (inv(+) gc) and as the specific inv(+) gc uptake mechanism. this model proposes that gonococci express a surface feature that mimics human chorionic gonadotropin (hcg), the cognate ligand for lhr, and that this structure is responsible for ... | 2000 | 10948117 |
| t-cell-independent responses to borrelia burgdorferi are critical for protective immunity and resolution of lyme disease. | the humoral immune response to borrelia burgdorferi during persistent infection is critical to both protective and disease-resolving immunity. this study examined the role of b cells in the absence of t cells during these events, using mice with selected immune dysfunctions. at 6 weeks postinfection, an interval at which arthritis resolves in immunocompetent mice, arthritis severity was equivalent among immunocompetent mice, alphabeta(+)-t-cell-deficient mice, and mice lacking both alphabeta(+) ... | 2000 | 10948143 |
| impaired control of brucella melitensis infection in rag1-deficient mice. | after intranasal inoculation, brucella melitensis chronically infects the mononuclear phagocyte system in balb/c mice, but it causes no apparent illness. adaptive immunity, which can be transferred by either t cells or antibody from immune to naive animals, confers resistance to challenge infection. the role of innate, non-b-, non-t-cell-mediated immunity in control of murine brucellosis, however, is unknown. in the present study, we documented that balb/c and c57bl/6 mice had a similar course o ... | 2000 | 10948160 |
| invasion and intracellular trafficking of brucella abortus in nonphagocytic cells. | brucella abortus is a facultative intracellular parasite that promotes its own internalization in nonphagocytic cells. the bacterium initially interacts with compartments of the early endocytic cascade, then rapidly segregates from this intracellular pathway and associates with the autophagocytic cascade. during the late stages of infection, brucella proliferates within the endoplasmic reticulum of host cells. | 2000 | 10955964 |
| cloning and characterization of the glucooligosaccharide catabolic pathway beta-glucan glucohydrolase and cellobiose phosphorylase in the marine hyperthermophile thermotoga neapolitana. | characterization in thermotoga neapolitana of a catabolic gene cluster encoding two glycosyl hydrolases, 1,4-beta-d-glucan glucohydrolase (ggha) and cellobiose phosphorylase (cbpa), and the apparent absence of a cellobiohydrolase (cbh) suggest a nonconventional pathway for glucan utilization in thermotogales. ggha purified from t. neapolitana is a 52.5-kda family 1 glycosyl hydrolase with optimal activity at ph 6.5 and 95 degrees c. ggha releases glucose from soluble glucooligomers, with a prefe ... | 2000 | 10960102 |
| residual virulence of brucella abortus in the absence of the cytochrome bc(1)complex in a murine model in vitro and in vivo. | to maintain survival in macrophages, brucella must overcome a hostile phagosomal environment defined as low ph, limited nutrition and low oxygen tension. the specific mechanisms utilized by brucella to surmount such unfavorable environmental factors in phagosomes are not well understood. in general, to adapt to a change in environmental oxygen tension, bacteria use different terminal oxidases that have different oxygen affinity. to survive in phagosomes where low oxygen tension exists, brucella, ... | 2000 | 10968951 |
| tnfa promoter polymorphism and susceptibility to brucellosis. | the aim of this study was to investigate the possible influence of the tumor necrosis factor alpha (tnfa) gene promoter polymorphisms and hla class ii genes on the susceptibility to or development of human brucellosis. tnfa genotypes (at positions -308 and -238) were determined in 59 patients with brucellosis and 160 healthy controls by polymerase chain reaction-restriction fragment length polymorphism. there were no significant differences between the patients and the controls for the tnfa-238 ... | 2000 | 10971514 |
| evaluation of primary binding assays for presumptive serodiagnosis of swine brucellosis in argentina. | an indirect enzyme-linked immunosorbent assay (ielisa), a competitive elisa (celisa), and a fluorescence polarization assay (fpa) for the presumptive serological diagnosis of swine brucellosis were evaluated using two populations of swine sera: sera from brucellosis-free canadian herds and sera from argentina selected based on positive reactions in the buffered antigen plate agglutination test (bpat) and the 2-mercaptoethanol (2-me) test. in addition, sera from adult swine from which brucella su ... | 2000 | 10973463 |
| an is711 element downstream of the bp26 gene is a specific marker of brucella spp. isolated from marine mammals. | dna polymorphism of the bp26 gene, coding for a diagnostic protein antigen for brucellosis, was assessed by pcr and restriction fragment length polymorphism analysis using primers to amplify the bp26 gene with its flanking regions. surprisingly, whereas pcr performed on dna of the reference strains of the six recognized brucella species produced a product of the expected size (1,029 bp), pcr performed on dna of three representative strains from marine mammals (from a seal, a dolphin, and a porpo ... | 2000 | 10973465 |
| identification of brucella abortus oxyr and its role in control of catalase expression. | we report the cloning and sequencing of the brucella abortus oxyr homolog and provide evidence that the transcription product of this gene binds to the b. abortus catalase promoter region. a gene replacement/deletion brucella oxyr mutant exhibits increased sensitivity to prolonged exposure to h(2)o(2) and is unable to adapt to h(2)o(2) in the environment. | 2000 | 10986275 |
| b-cell deficiency predisposes mice to disseminating anaerobic infections: protection by passive antibody transfer. | we have previously demonstrated that a high proportion of rag-2 scid knockout mice, which lack t and b cells, develop orofacial abscesses and disseminated infections following pulpal infection, whereas immunocompetent control mice do not. in the present study, we sought to identify the components of the adaptive immune response which contribute to protection against disseminating anaerobic infections and sepsis. for this purpose, various genetically engineered immunodeficient mice were employed, ... | 2000 | 10992465 |
| identification and characterization of the brucella abortus phosphoglucomutase gene: role of lipopolysaccharide in virulence and intracellular multiplication. | smooth lipopolysaccharide (lps) of brucella abortus has been reported to be an important virulence factor, although its precise role in pathogenesis is not yet clear. while the protective properties of lps against complement are well accepted, there is still some controversy about the capacity of rough mutants to replicate intracellularly. the b. abortus phosphoglucomutase gene (pgm) was cloned, sequenced, and disrupted. the gene has a high index of identity to agrobacterium tumefaciens pgm but ... | 2000 | 10992476 |
| transcriptional activation of the htra (high-temperature requirement a) gene from bartonella henselae. | bacterial htra genes are typically activated as part of the periplasmic stress response and are dependent on the extracytoplasmic sigma factor rpoe. a putative promoter region, p1, of the sigma(e)-type heat-inducible promoters has previously been identified upstream of the htra gene of bartonella henselae. further analysis of the htra mrna by primer extension demonstrated that transcription initiates from p1 and a second region downstream of p1. this second promoter region, termed p2, had no seq ... | 2000 | 10992509 |
| brucella abortus tandem repeated atp-binding proteins, bapa and bapb, homologs of haemophilus influenzae lktb, are not necessary for intracellular survival. | brucella abortus actively secretes materials and uptakes nutrients to maintain the survival and multiplication of the bacteria in host cells. atp-binding cassette (abc) transporters can uptake or secrete diverse materials across the bacterial membrane, and thus, abc transporters may be important for survival of the pathogen in the host. in the present study, the b. abortus genes encoding tandem repeated brucella atp-binding proteins, bapa and bapb, were identified. the deduced amino acid sequenc ... | 2000 | 10993743 |