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minimum inhibitory concentration breakpoints and disk diffusion inhibitory zone interpretive criteria for tilmicosin susceptibility testing against pasteurella spp. associated with bovine respiratory disease.tilmicosin is a novel macrolide antibiotic developed for exclusive use in veterinary medicine. the first tilmicosin-containing product was approved to treat bovine respiratory disease associated with pasteurellae. the development of antimicrobial susceptibility testing guidelines for tilmicosin was predicated on the relationship of clinical efficacy studies that demonstrated a favorable therapeutic outcome, on pharmaco-kinetic data, and on in vitro test data, as recommended by the national commi ...19968844577
hemodynamic responses to pasteurella haemolytica inoculation in calves given type 2 serotonergic antagonist.the effects of saline (control, group c) and metrenperone (treated, group m) on systemic and pulmonary hemodynamics were determined in conscious 7- to 15-day-old calves after they were intratracheally inoculated with pasteurella haemolytica. metrenperone, a specific serotonin (5-hydroxytryptamine) receptor antagonist, was injected intramuscularly (100 micrograms.kg-1) 2 h after the calves were inoculated. central venous, pulmonary arterial and capillary wedge, and systemic arterial pressures wer ...19968884022
the fractional inhibitory concentration index of antimicrobial agents for bacteria and mycoplasma isolated from the nasal swabs of cattle with respiratory diseases.we investigated the effect of thiamphenicol plus lincomycin (tp + lcm) and thiamphenicol plus tylosin (tp + ts) combinations using checker board method on the growth of pasteurella (p.) multocida, p. haemolytica and mycoplasma (m.) bovis by calculating the fractional inhibitory concentration index (fic index). the results showed that the fic indexes of the tp + lcm combination for p. multocida, p. haemolytica and m. bovis were 0.36 +/- 0.10, 0.72 +/- 0.09 and 0.81 +/- 0.18, respectively. the fic ...19968877979
the pasteurella haemolytica o-sialoglycoprotein endopeptidase is inhibited by zinc ions and does not cleave fetuin.culture supernatants of pasteurella haemolytica a1 contain an o-sialoglycoprotein endopeptidase that cleaves human glycophorin a. this enzyme is inhibited by micromolar concentrations of zn2+. it can be separated from a neuraminidase activity in culture supernatants by ion-exchange chromatography. the neuraminidase activity can cause the de-sialation of the bovine soluble sialoglycoprotein, fetuin. however fetuin is not cleaved proteolytically either by culture supernatants from p. haemolytica a ...19968602834
efficacy of a subcutaneously administered, ultraviolet light-killed pasteurella haemolytica a1-containing vaccine against transthoracic challenge exposure in goats.to determine the effectiveness of pasteurella haemolytica biovar a, serovar 1 (ph a1) killed by uv light and incorporated with an oil adjuvant or carriers.19968836369
evaluation of a pcr for detection of actinobacillus pleuropneumoniae in mixed bacterial cultures from tonsils.a pcr for the detection of actinobacillus pleuropneumoniae was evaluated. all of 102 field, isolates of a, pleuropneumoniae reacted in the pcr by amplification of a 985 bp product. no pcr amplification product was observed when examining strains of a. ureae, a. capsulatus, a. hominis, a. equuli, a, rossii, a. suis, escherichia coli, bordetella bronchiseptica. streptococcus suis, pasteurella haemolytica, pasteurella multocida, haemophilus parasuis, haemophilus taxon minor group, haemophilus taxon ...19968828126
[development of resistance in infectious agents of agricultural animals in germany (1990-1994)--a review].antibiograms received from veterinary laboratories during the 1990-1994 period were recorded and evaluated with the aid of a computer program. based on 70 tables giving information about th most important pathogens, the resistance behaviour of e. coli in cattle, swine, chicken, and turkey, that of pasteurella haemolytica and p. multocida in cattle and swine and that of staphylococcus aureus and streptococcus agalactiae in cattle have been in synoptic form. attention is drawn to the increase in r ...19968998938
tandem repeats of the tetramer 5'-caat-3' present in lic2a are required for phase variation but not lipopolysaccharide biosynthesis in haemophilus influenzae.a novel lipopolysaccharide (lps) biosynthesis gene, lic2b, which is required for the biosynthesis of a phase-variable lps structure expressed by haemophilus influenzae rm7004 is described. the product of this gene is homologous to lic2a and the recently described lps biosynthetic enzymes, lgtb from neisseria gonorrhoea and lgte from neisseria meningitidis, and lpsa from pasteurella haemolytica. of this family of enzymes only lic2a contains the repetitive tetrapeptide motif (sinq)(n) encoded by m ...19968861214
characterization of bovine pulmonary and serum antibody responses after parenteral or intrapulmonary vaccination with live pasteurella haemolytica.pulmonary and serum antibody responses were evaluated in eight calves vaccinated [four intrapulmonary-right diaphragmatic lobe (ip) and four subcutaneous (sc)] with pasteurella haemolytica a1 (ph-1) impregnated agar beads and eight respective sham-vaccinated calves. experimental and sham groups were challenged in both diaphragmatic lobes with ph-1 34-37 d after vaccination (dav) and necropsied 6 d after challenge (dac; 40-43 dav). igg antibodies contained in fluids from the diaphragmatic lobes o ...19968814980
detection of mycoplasma ovipneumoniae and pasteurella haemolytica antigens by an immunoperoxidase technique in pneumonic ovine lungs.four hundred twenty pneumonic lungs from lambs were examined for mycoplasma ovipneumoniae and pasteurella haemolytica by an immunoperoxidase technique using an extravidin-biotin-peroxidase complex method in formalin-fixed, paraffin-embedded sections. histologic examination of tissue sections revealed strong positive reactions in 60.9% and 68.3% of the lungs against m. ovipneumoniae and p. haemolytica, respectively. m. ovipneumoniae and p. haemolytica antigens were observed at the surface and/or ...19968826008
differences in the distribution of cd34 epitopes on normal haemopoietic progenitor cells and leukaemic blast cells.the cd34 molecule expressed on haemopoietic progenitor cells contains a large number of epitopes whose expression may be related to the maturation or function of the cells. monoclonal antibodies specific for different epitopes have been reported to detect different numbers of cd34+ leukaemic blast cells. we wanted to confirm this observation and study whether parallel findings could be observed for normal haemopoietic progenitor cells. the cells were immunophenotyped by flow cytometry with a ser ...19968826880
genetic and immunological analyses of a 38 kda surface-exposed lipoprotein of pasteurella haemolytica a1.pasteurella haemolytica serotype a1 is the bacterial pathogen most frequently isolated from the lungs of cattle with bovine respiratory disease. as part of a study to characterize p. haemolytica antigens which are important in eliciting resistance to pneumonic pasteurellosis, we have cloned and sequenced the gene encoding a 38 kda lipoprotein, lpp38. the deduced amino acid sequence of lpp38 is similar to those of the escherichia coli polyamine transport proteins potd (70%) and potf (33%). p. hae ...19968870194
respiratory tract disease and mucosal colonization by pasteurella haemolytica in transported cattle.to follow incidence of pasteurella haemolytica (ph) in the upper respiratory tract of healthy calves at the farm and through the marketing process, and to determine the effect of vaccination on ph colonization of the upper respiratory tract and on the incidence of respiratory tract disease (rtd).19968874726
cat iii chloramphenicol resistance in pasteurella haemolytica and pasteurella multocida isolated from calves.chloramphenicol, which had been used extensively for antimicrobial veterinary therapy, was prohibited in europe in 1994. soon after it became available, resistance to this drug was detected, generally conferred by plasmids encoding inactivating enzymes, the chloramphenicol acetyltransferases (cat), in gram-negative as well as in gram-positive bacteria. in the last few years, resistance to antibiotics emerged in pasteurella strains from breeding herds and this evolution was followed by a national ...19968877534
[resistance pattern of bovine pasteurella].the sensibility of 375 pasteurellae of bovine origin (215 pasteurella multocida--and 160 pasteurella haemolytica--strains) was examined against 16 antibiotics or chemotherapeutics by agar diffusion technique. a great part of the strains was resistant to oxacillin (41,18%), tylosin (79,14%), streptomycin (53,21%), sulfonamides (57,33%) and tetracycline (47,20%). only a few resistant strains were found for cephalothin (5,07%), polymyxin b (0,27%) and enrofloxacin (0,53%). while 16,27% of all isola ...19968694744
characterization of a pasteurella multocida plasmid and its use to express recombinant proteins in p. multocida.the complete nucleotide sequence of a naturally occurring 5.36-kb streptomycin and sulphonamide resistance plasmid, designated pig1, isolated from type d pasteurella multocida was determined. a 1.6-kb noncoding region and a 1.4-kb region encoding three putative proteins were shown by sequence homologies and functional characterizations to be involved in the replication and mobilization of pig1, respectively. the remaining sequence carried an unusual arrangement of streptomycin- and sulphonamide- ...19979073583
characterisation of the leukotoxin produced by different strains of pasteurella haemolytica.pasteurella haemolytica isolates from cattle and sheep, including representatives of different serotypes and untypable strains, were examined for leukotoxin (lkt) production at the end of the log phase of growth in brain heart infusion broth. there were marked differences in leukotoxic activity in culture supernate samples, as measured by chemiluminescence-inhibition assays with bovine and ovine neutrophils, even between strains of the same serotype. there was also some variation in the amount a ...19979128191
divergent activity and function of superoxide dismutases in pasteurella haemolytica serotypes a1 and a2 and pasteurella trehalosi serotype t10.representative strains of pasteurella haemolytica serotypes a1 and a2 and pasteurella trehalosi serotype t10 were examined for the presence of superoxide dismutase. visualisation of superoxide dismutase enzyme activity on polyacrylamide gels, and specific inhibition with potassium cyanide verified a copper/zinc (cu/zn) superoxide dismutase only in serotype a2 whereas serotypes a1 and t10 showed other superoxide dismutase activity. using a simple freeze-thaw method the cellular location of supero ...19979170262
detection of rtx toxin genes in gram-negative bacteria with a set of specific probes.the family of rtx (rtx representing repeats in the structural toxin) toxins is composed of several protein toxins with a characteristic nonapeptide glycine-rich repeat motif. most of its members were shown to have cytolytic activity. by comparing the genetic relationships of the rtx toxin genes we established a set of 10 gene probes to be used for screening as-yet-unknown rtx toxin genes in bacterial species. the probes include parts of apxia, apxiia, and apxiiia from actinobacillus pleuropneumo ...19979172345
growth of pasteurella haemolytica and production of its leukotoxin in semi-defined media.to develop semi-defined media that support growth of the bovine pathogen, pasteurella haemolytica, and use them to examine production of leukotoxin and an arginine-binding protein by this organism.19979215452
nitric oxide production following in vitro stimulation of ovine pulmonary alveolar macrophages.production of inducible nitric oxide (no) as measured by nitrite in supernatant from ovine pulmonary alveolar macrophage (pam) cultures was assessed following stimulation of pam with live cells and supernatants from corynebacterium pseudotuberculosis and pasteurella haemolytica cultures; purified bacterial lipopolysaccharide derived from both escherichia coli and pasteurella haemolytica alone and in combination with interferon-gamma or lymphocyte conditioned medium; or ovine lentivirus. pam cult ...19979223233
role of tissue factor in intra-alveolar fibrin deposition and coagulopathy associated with pneumonic pasteurellosis in cattle.to determine the role of tissue factor (tf) in the coagulation events leading to intra-alveolar fibrin deposition and intravascular thrombosis associated with pneumonic pasteurellosis in cattle.19978989492
bovine respiratory tract disease caused by bovine viral diarrhea virus.although several viruses and bacteria are capable of inducing bovine respiratory tract disease, a pivotal organism in the cause of this complex disease may be bovine viral diarrhea virus (bvdv). circumstantial evidence has long supported this hypothesis. it is frequently present in diseased respiratory tract tissues often together with other viruses or bacteria. field observations suggest marked synergism occurs. researchers have confirmed that, in most instances, the virus itself elicits only a ...19979368990
refolding of recombinant pasteurella haemolytica a1 glycoprotease expressed in an escherichia coli thioredoxin gene fusion system.pasteurella haemolytica a1 secretes an o-sialoglycoprotein endopeptidase (ec. 3.4.24.57) (glycoprotease: gcp) which is specific for o-linked sialoglycoproteins. when the cloned gene is expressed in escherichia coli, the recombinant glycoprotease (rgcp) is secreted to the periplasm where it is present as a disulfide-linked aggregate which lacks enzymatic activity. in vitro refolding and activation of rgcp by mammalian protein disulfide isomerase (pdi) or by the e. coli chaperones (dnak, dnaj and ...19979314606
the humoral immune response in cattle after immunization with a multivalent ibr/pi3/pasteurella haemolytica a1 leukotoxin vaccine.a multivalent vaccine consisting of inactivated bovine herpes virus-1 (bhv-1), also known as infectious bovine rhinotracheitis virus (ibr), para-influenza type-3 virus (pi3) and the leukotoxin of pasteurella haemolytica a1, were combined with the addition of aluminium hydroxide as adjuvant, and administered to post-weaned calves, and the serum tested for seroconversion to each antigen. two groups of calves (n = 150 and n = 68) were used and were randomly divided into three subgroups. the first g ...19979467176
bacterial pneumonia.bacteria play a critical role in the severe pneumonia and fatalities associated with the bovine respiratory disease complex. although numerous bacteria have the potential to cause pneumonia, only a small number of these are responsible for the majority of cases of disease. virulence and immunogenic characteristics of these organisms are important determinants of the host response to infection. these bacterial characteristics are reviewed and applied to a discussion of the epidemiology, pathogene ...19979368991
bacterial ghosts as multifunctional vaccine particles.expression of cloned phix174 gene e in gram-negative bacteria results in lysis of the bacteria by formation of an e-specific transmembrane tunnel structure built through the cell envelope complex. bacterial ghosts have been produced from a variety of bacteria including escherichia coli. salmonella typhimurium, salmonella enteritidis, vibrio cholerae, klebsiella pneumoniae, actinobacillus pleuropneumoniae, haemophilus influenzae, pasteurella haemolytica, pasteurella multocida, and helicobacter py ...19979382740
the leukocyte common antigen (cd45) on human pre-b leukemia cells: variant glycoprotein form expression during the cell exposure to phorbol ester is blocked by a nonselective protein kinase inhibitor h7.the human pre-b acute lymphoblastic leukemia cell line reh6 was utilized for characterization of cd45 glycoprotein by monoclonal antibodies (mab) recognizing four distinct cd45 antigen specificities, i.e. nonrestricted cd45, restricted cd45ra, cd45rb and cd45r0. immunoprecipitation revealed two antigen specificities on reh6 cells of m.w. 220 kda and 190 kda, both presenting wide range of isoelectric point pi approximately 6.0-7.5. nonrestricted cd45 epitopes were not affected by the sialyl acid ...19979473774
comparison of the recombinant and authentic forms of the pasteurella haemolytica a1 glycoprotease.the o-sialoglycoprotein endopeptidase (glycoprotease, gcp) is secreted by pasteurella haemolytica a1, a gram-negative pathogen associated with bovine pneumonic pasteurellosis. when the cloned gcp gene is expressed in escherichia coli, the recombinant glycoprotease (rgcp) is exported to the periplasm but does not exhibit enzymatic activity. polyclonal calf sera and murine monoclonal antibodies to rgcp were used for the further immunological and biochemical characterization of the authentic and re ...19979037761
epithelial antibiotic induced in states of disease.epithelial defensins provide an active defense against the external microbial environment. we investigated the distribution and expression of this class of antimicrobial peptides in normal cattle and in animals in varying states of disease. beta-defensin mrna was found to be widely expressed in numerous exposed epithelia but was found at higher levels in tissues that are constantly exposed to and colonized by microorganisms. we observed induction in ileal mucosa during chronic infection with myc ...19979238038
characterization of the pasteurella haemolytica transferrin receptor genes and the recombinant receptor proteins.the tbpa and tbpb genes encoding the transferrin receptor proteins, tbpa and tbpb, from pasteurella haemolytica a1 were cloned, sequenced and expressed in escherichia coli. the genes were organized in a putative operon arrangement of tbpb- tbpa. the tbpb gene was preceded by putative promoter and regulatory sequences, and followed by a 96 base pair intergenic sequence in which no promoter regions were found, suggesting that the two genes are coordinately transcribed. the deduced amino acid seque ...19979405205
effect of simulated stress on susceptibility of bighorn sheep neutrophils to pasteurella haemolytica leukotoxin.we examined the effects of simulated stress on susceptibility of rocky mountain bighorn sheep (ovis canadensis canadensis) neutrophils to pasteurella haemolytica leukotoxin in a blocked, crossover experiment. ten captive-raised bighorn sheep were sampled 10 hr after separate administrations of long-acting adrenocorticotrophic hormone (acth) gel and normal saline (control). we then compared in vitro leukotoxin-dependent neutrophil death rates after exposure to culture supernatants from four uniqu ...19979249702
effects of trypanosoma evansi on the output of cells from a lymph node draining the site of pasteurella haemolytica vaccine administration.the prefemoral efferent lymphatics of sheep infected with trypanosoma evansi and inoculated with p. haemolytica vaccine and of those given only the vaccine, were surgically cannulated to study the effects of the infection on the total cellular output and output of blast cells from the node in response to the vaccine. t. evansi delayed and depressed the increases in total cell and lymphoblast outputs. in uninfected sheep, the total cellular output increased and peaked at more than twice the preva ...19979263845
bacterial identity and characteristics in healthy and unhealthy respiratory tracts of sheep and calves.the aim of this study was to compare different bacteriological aspects of the respiratory systems of healthy (h) versus unhealthy (uh) animals with respiratory signs. the prevalence of different bacterial species was determined in the upper and lower respiratory tract of h and uh najdi sheep, somali sheep and holstein calves. the characteristics of pasteurella spp. isolates, and the biotype of pasteurella haemolytica were identified in h and uh animals, eighteen out of 28 (64.3%) of the identifi ...19979266661
computer-based analyses of the protein constituents of transport systems catalysing export of complex carbohydrates in bacteria.bacteria synthesize and secrete an array of complex carbohydrates including exopolysaccharides (epss), capsular polysaccharides (cpss), lipopolysaccharides (lpss), lipo-oligosaccharides (loss) and teichoic acids (tcas). we have analysed the families of homologous proteins that appear to mediate excretion of complex carbohydrates into or across the bacterial cell envelope. two principal families of cytoplasmic-membrane transport systems appear to drive polysaccharide export: polysaccharide-specif ...19979274022
evolutionary genetics of pasteurella haemolytica isolates recovered from cattle and sheep.genetic diversity and relationships among 194 pasteurella haemolytica isolates, which were recovered predominantly from cattle (39%) and sheep (58%) suffering from pneumonic pasteurellosis in the united kingdom, germany, and the united states, were estimated by examination of allelic variation at 18 enzyme-encoding loci detected by multilocus enzyme electrophoresis. the isolates formed two major divisions. one included 178 pasteurella haemolytica sensu stricto strains representing serotypes a1, ...19979284123
serum antibody responses of cattle vaccinated with partially purified native pasteurella haemolytica leukotoxin.the objective of these experiments was to study the serum antibody responses of cattle to partially purified, native pasteurella haemolytica a1 leukotoxin (lkt) formulated with a commercial aluminum hydroxide-dda-bromide adjuvant. in two experiments, calves received two intramuscular injections 21 days apart and sera were obtained periodically. serum antibody responses to p. haemolytica outer membrane proteins (omps), formalinized p. haemolytica, and lkt were determined. in experiment a, holstei ...19979302755
isolation of pasteurella haemolytica from grass, drinking water, and straw bedding used by sheep.pasteurella haemolytica was isolated from three of 18 grass samples and four of 18 water samples collected from two grazing fields occupied by sheep. this microorganism was also isolated from three of nine straw bedding samples collected from a pen housing ewes affected by mastitis caused by p. haemolytica. the same ewes developed scabbed papilloma-like lesions on the teat and udder skin. these lesions were colonized by p. haemolytica of various serotypes. colder, wetter weather seems to prolong ...19979321460
further studies of the relationships among strains classified as taxon 15, taxon 18, taxon 20, (pasteurella) granulomatis or the (pasteurella) haemolytica-complex in ruminants using quantitative evaluation of phenotypic data.ninety-three trehalose-negative (p.) haemolytica-like strains of ruminant, porcine and leprine origin were investigated. a quantitative evaluation of phenotypic tests was used and the results obtained were compared with those from 246 previously investigated ruminant strains. cluster analysis of the results obtained displayed most of the taxa as distinct groups which could be related to differences in key characters. although only minor phenotypic differences were observed between the taxa inves ...19979361379
genotypic relationships among strains classified under the (pasteurella) haemolytica-complex as indicated by ribotyping and multilocus enzyme electrophoresis.two-hundred and one strains classified under the (pasteurella) haemolytica-complex isolated from cattle, sheep, deer, pigs, hares and rabbits were investigated by ribotyping. fifty-nine of these strains were selected for further studies using multilocus enzyme electrophoresis (mee). a correlation between the clusters identified by ribotyping and mee was demonstrated and the results furthermore indicated that a genetic basis exists for most clusters previously outlined by the use of quantitative ...19979361380
effects of pasteurella haemolytica leukotoxin and lipopolysaccharide on histamine, prostanoid, and leukotriene release by bovine lung parenchyma in vitro.to identify the effect of pasteurella haemolytica lipopolysaccharide (lps) and leukotoxin (lkt) on spontaneous and calcium ionophore-induced histamine and inflammatory mediator release from isolated bovine lung parenchyma.19979361883
cloning and characterization of the exbb-exbd-tonb locus of pasteurella haemolytica a1.a recombinant plasmid (pmg1) carrying pasteurella haemolytica a1 dna which complements a tonb mutation of escherichia coli has been isolated. e. coli tonb mete which carries pmg1 exhibits growth kinetics in the presence of vitamin b12 similar to that of the wild-type host. in addition, the complemented e. coli is susceptible to killing by bacteriophage phi 80 and colicin b. analysis of the nucleotide sequence in the complementing dna showed that it codes for three genes in the order of exbb-exbd ...19979074497
relationships among strains classified with the ruminant pasteurella haemolytica-complex using quantitative evaluation of phenotypic data.the phenotypic relationships among 246 trehalose-negative strains classified under the [pasteurella] haemolytica-complex in ruminants were investigated by clustering and multidimensional ordinations based upon 79 phenotypic characters. a quantitative evaluation of phenotypic data using a 5-level scoring system is presented permitting a comprehensive utilization of the recorded phenotypic variation among the strains in the analyses. clustering and ordination analyses display complementary aspects ...19979144907
association of pasteurella haemolytica, pasteurella multocida and haemophilus somnus with pneumonia in calves.pathological and bacteriological observations were made on 100 (0.98%) pneumonic lungs of 10140 slaughtered beef calves during march 1995-june 1996 period. gross lesions were mainly lobular and occasionally lobar pattern and, were frequently observed in the pars cranialis of lobus cranialis dexter. in histological examination, proliferative-exudative pneumonia was observed in 79 cases, and proliferative pneumonia alone in 21 cases. in bacteriological examination, pasteurella haemolytica. pasteur ...19979151475
effects of copper deficiency and copper deficiency coupled with high dietary iron or molybdenum on phagocytic cell function and response of calves to a respiratory disease challenge.a study was conducted to determine the effects of supplementing a diet marginally deficient in copper (cu) with iron (fe), molybdenum (mo), or cu on phagocytic cell function and disease resistance of calves. thirty-one calves were born to heifers fed a corn silage-based diet containing 4.5 mg of cu/kg. treatments consisted of 1) control (con; no supplemental cu, fe, or mo), 2) 600 mg of fe added/kg (fe), 3) 5 mg of mo added/kg (mo), or 4) 10 mg of cu added/kg of dm (cu). activity of superoxide d ...19979110227
increase of glycocalyx and altered lectin agglutination profiles of pasteurella haemolytica a1 after incubation in bovine subcutaneous tissue chambers in vivo or in ruminant serum in vitro.pasteurella haemolytica serotype a1 (bovine strain ok) was incubated for 2 and 6 h in bovine subcutaneous tissue chambers in vivo, and ovine strain 82-25 and bovine strain l011 were incubated in vitro for 2 h in heat-inactivated ovine or bovine serum from which gamma globulin had been depleted by protein g affinity chromatography to assess changes in morphology and lectin agglutination profiles (strains 82-25 and l101 only). cells, removed from chambers after 2 h, were covered with an extensive, ...19979038303
plasmids for heterologous expression in pasteurella haemolytica.new cloning and expression vectors that replicate both in pasteurella haemolytica and in escherichia coli were constructed based on a native sulfonamide (sur) and streptomycin (smr) resistant plasmid of p. haemolytica called pyfc1. each shuttle vector includes an mcs and a selectable antibiotic resistance marker that is expressed in both organisms. plasmid pnf2176 carries the p. haemolytica rob-1 beta-lactamase gene (blap, apr) and pnf2214 carries the tn903 aph3 kanamycin resistance (kmr) elemen ...19979074498
development and characterisation of a model of bovine inflammation.two dialysis sacs each containing 50 ml dextran sulphate solution were implanted into the peritoneal cavities of five three month-old calves. one sac was inoculated with pasteurella haemolytica or streptococcus uberis and the second sac served as an uninoculated control. samples of sac fluid removed after 0, four, six, eight, 15, 24, 36 and 48 hours and then at 24 hour intervals after inoculation revealed bacterial growth up to 9.0 log10 cfu ml-1 by two to three days after inoculation. concentra ...19979160425
udder orf infection and its role in ovine clinical mastitis caused by pasteurella haemolytica.during an experimental study of ovine subclinical mastitis caused by coagulase-negative staphylococci, an outbreak of contagious ecthyma occurred among ewes unvaccinated against parapox virus. the same group of ewes developed a high rate (43.7%) of clinical mastitis caused by pasteurella haemolytica. the rate of clinical mastitis among ewes vaccinated against parapox virus was very low (3.7%) suggesting that the presence of orf in the unvaccinated ewes was contributing to the high rate of clinic ...19979176868
two genes encoding serine protease homologues in serratia marcescens and characterization of their products in escherichia coli.a serine protease (ssp) of serratia marcescens is one of the extracellular enzymes secreted from this gram-negative bacterium. ssp is produced as a large precursor and converted to a mature protein by cleavages removing an nh2-terminal signal sequence and a cooh-terminal pro-region. this cooh-terminal pro-region is integrated into the outer membrane and has a functional role for the export of the mature protein across the outer membrane. southern hybridization analysis with a dna fragment encodi ...19979192732
efficacy of the combination sodium ceftiofur-flumethasone in the treatment of experimental pasteurella haemolytica bronchopneumonia in calves.severe acute bronchopneumonia was induced in 18 conventional friesian-holstein calves by inoculating them intratracheally with pasteurella haemolytica type a1. six of the calves received no treatment and served as controls. six of the calves were treated with sodium ceftiofur and six were treated with sodium ceftiofur and flumethasone. the mortality rate in the group of calves treated with sodium ceftiofur and flumethasone was significantly lower and their clinical and haematological parameters ...19979197206
generation of targeted nonpolar gene insertions and operon fusions in pasteurella haemolytica and creation of a strain that produces and secretes inactive leukotoxin.an efficient method for targeted gene inactivation and generation of chromosomal gene fusions in pasteurella haemolytica has been devised and used to create an lktc::cat operon fusion by allelic exchange at the leukotoxin gene cluster (lktcabd). a copy of the lktc gene was insertionally inactivated by using a nonpolar, promoterless cat cassette and then delivered into p. haemolytica on a shuttle vector. plasmid incompatibility was used to detect clones where double recombination events had occur ...19979199425
treatment of experimentally induced pneumonic pasteurellosis of young calves with tilmicosin.twenty four (24) healthy male holstein calves (< 70 kg) were each experimentally infected by intrabronchial inoculation of 4.0 x 10(9) viable cells of pasteurella haemolytica-ai (b122) at time = 0 h. at 1 h following inoculation animals received either: 1) sham treatment with sterile 0.85% saline sc (n = 12); or 2) a single injection of 10 mg tilmicosin per kg body weight (n = 12). calves that were non-infected and tilmicosin-treated were also included for determining tilmicosin concentrations i ...19979242998
influence of immunization on the pulmonary inflammatory response of rabbits induced by pasteurella haemolytica a1 lipopolysaccharide.immune complex formation has long been thought to play a role in the pathogenesis of pasteurella haemolytica pneumonia. this study in laboratory rabbits was designed to investigate immune-mediated damage in respiratory tissue caused by lipopolysaccharide (lps). severe lesions were induced by the intratracheal (it) injection of p. haemolytica a1 lps (50 micrograms) into rabbits previously immunized with p. haemolytica killed whole cells emulsified with freund's incomplete adjuvant (fia); these le ...19979352438
serotyping and enzyme characterization of pasteurella haemolytica and pasteurella multocida isolates recovered from pneumonic lungs of stressed feeder calves.ninety-one isolates of pasteurella multocida (pm)and 124 of pasteurella haemolytica (ph) were recovered from the lungs of calves that died of bovine respiratory tract disease (brtd). nine pm enzyme profiles (a through i) and 9 ph enzyme profiles (j through r) were determined for the pasteurella isolates. the pm isolates were relatively evenly divided among the enzyme profiles, with one exception, profile i. the ph isolates were not evenly distributed among the profiles. fifty of the 91 pm isolat ...19979058546
nasal carriage of pasteurella haemolytica serotypes by sheep and goats in jordan. 19979316235
pulmonary venous thrombosis in caprine pasteurella pneumonia.a 3-year-old angora goat that developed acute fibrinous pleuropneumonia associated with pasteurella haemolytica infection had thrombotic occlusion of a large pulmonary vein. thrombosis of pulmonary capillaries occurs in pneumonic pasteurellosis, but large vessels are not commonly affected. this unusual lesion may reflect the procoagulant effect of pasteurella endotoxin on vascular endothelium. an incidental observation was the presence of myocardial-type muscle fibres in the tunica media of the ...19979179755
aspects of the pharmacokinetics of doxycycline given to healthy and pneumonic east african dwarf goats by intramuscular injection.the effect of experimentally induced pasteurella haemolytica pneumonia on the pharmacokinetics of doxycycline (doxycen retard) administered intramuscularly was studied in seven east african dwarf goats. the study was conducted in two consecutive phases, separated by a washout period of four weeks. the experimental infection, induced by intratracheal administration of 5 ml of 10(7) to 10(9) cfu/ml of pasteurella haemolytica, produced a temperature rise, depression and laboured breathing within 6- ...19979266665
purification and partial characterization of the ompa family of proteins of pasteurella haemolytica.this study was conducted to partially characterize and identify the purity of two major outer membrane proteins (omps) (with molecular weights of 32,000 and 35,000 [32k and 35k, respectively]) of pasteurella haemolytica. the 35k and 32k major omps, designated pasteurella outer membrane proteins a and b (poma and pomb, respectively), were extracted from p. haemolytica by solubilization in n-octyl polyoxyl ethylene. the p. haemolytica strain used was a mutant serotype a1 from which the genes expre ...19978975914
structure-function studies of the adenylate cyclase toxin of bordetella pertussis and the leukotoxin of pasteurella haemolytica by heterologous c protein activation and construction of hybrid proteins.the adenylate cyclase toxin (cyaa) from bordetella pertussis and the leukotoxin (lkta) from pasteurella haemolytica are members of the rtx (stands for repeats in toxin) family of cytolytic toxins. they have pore-forming activity and share significant amino acid homology but show marked differences in biological activity. cyaa is an invasive adenylate cyclase and a weak hemolysin which is active on a wide range of mammalian cells. lkta is a cytolytic protein with a high target cell specificity an ...19979006045
binding of pasteurella haemolytica leukotoxin to bovine leukocytes.pasteurella haemolytica is the principal bacterial pathogen in the bovine respiratory disease complex. this organism produces an exotoxin (referred to as leukotoxin) during logarithmic-phase growth that is a potent leukocyte-modulating agent. at low concentrations, it activates neutrophils and mononuclear phagocytes to release inflammatory mediators, while at the same time making these cells destined to undergo apoptotic cell death. at higher concentrations, the toxin causes rapid swelling and l ...19979284143
a putative leucine zipper activator of pasteurella haemolytica leukotoxin transcription and the potential for modulation of its synthesis by slipped-strand mispairing.a pasteurella haemolytica cosmid clone that activates leukotoxin transcription in escherichia coli has been isolated. the activator locus, alxa, is part of a continuous open reading frame that includes the type i hsdm methylase gene. alxa and hsdm peptides are processed from a precursor, and translation of the polyprotein can be modulated by slipped-strand mispairing across a pentanucleotide repeat, acagc, within the 5' end of alxa-hsdm. extracts containing alxa can bind to a leukotoxin promoter ...19979284183
efficacy of doxycycline in a goat model of pasteurella pneumonia.the clinical efficacy of doxycycline (doxycen, cenavisa, spain), a long-acting preparation, was evaluated for treatment of pasteurella haemolytica infection in 6 goats. one goat was not infected and served as a control. the disease was induced by intratracheal inoculation of 10(7) to 10(9) cfu of p. haemolytica. confirmation of respiratory disease was based on evidence of appropriate clinical signs. before and after initiation of doxycycline treatment on day 10, each goat was examined daily. thr ...19979291074
isolation and characterization of the integration host factor genes of pasteurella haemolytica.using a bacteriophage lambda complementation system in escherichia coli, we cloned genes encoding subunits of the heterodimeric dna binding/bending protein, integration host factor, from the bovine pathogen, pasteurella haemolytica. complementation of ihfa and ihfb mutations in e. coli demonstrated that the p. haemolytica gene products form functional heterologous heterodimers. the ihfa and ihfb genes encode polypeptides predicted to be 99 and 93 amino acids long, respectively, and are very simi ...19979011038
expression of tissue factor in experimental bovine pneumonic pasteurellosis and endotoxemia.tissue factor (tf), a cell surface-associated cofactor and activator of coagulation factor vii, has been implicated in the local and systemic activation of coagulation associated with sepsis. this study describes the pattern of tf expression in experimental bovine pneumonic pasteurellosis and endotoxemia. immunohistochemical techniques were used to localize tf antigen in tissue sections. tissue factor expression was not observed in tissues from control animals. in response to pasteurella haemoly ...199712658585
purification and characterization of a 31-kilodalton iron-regulated periplasmic protein from pasteurella haemolytica a1.a prominent iron-regulated periplasmic protein was purified from pasteurella haemolytica grown in an iron-deficient chemically defined medium. the protein was purified by anion exchange chromatography and appeared as a single band by sds-page with a molecular weight of 32,000. a yield of five mg was obtained from 91 mg of protein extract. the iron-regulated protein existed as a monomer in the native state with an average molecular weight of 29,877 as determined by analytical ultracentrifugation. ...19979413558
[long-chain fatty acids of pasteurella multocida nad pasteurella haemolytica].the relative contents of long-chain fatty acids in p. multocida and p. haemolytica were investigated. a dependence on the composition of the broth was established. accordingly, comparative quantitative studies on fatty acid contents have to be conducted using bacteria grown with the same lot of broth medium. as for p. multocida, there were significant differences between the serovars (c14 in tdhm and c16, delta 2c18 in bpl). these differences are, however, not significant to replace serotyping. ...199710084940
[investigation of outer membrane proteins of pasteurella. 2: iron-regulated outer membrane proteins of pasteurella multocida and pasteurella haemolytica].pasteurella multocida and pasteurella haemolytica produce specific proteins in the outer membrane under iron-depleted conditions. pasteurella multocida serovar a expresses these proteins of molecular masses of 76 and 96 kda as determined by electrophoresis. the analogous serovar d produces a further iron-regulated protein of 85 kda. the pasteurella haemolytica strains of serovar a1, a6 and t contain iron-regulated outer membrane proteins of molecular masses of 71, 77 and 100 kda. these proteins ...199710084945
evaluation of a multivalent pasteurella haemolytica vaccine in bighorn sheep: safety and serologic responses.we examined effects of a multivalent pasteurella haemolytica vaccine (serotypes a1, a2, t10) on humoral immune responses and p. haemolytica isolation rates in bighorn sheep (ovis canadensis). thirty captive bighorns, divided into groups of three on the basis of age, sex, and previous history of pneumonic pasteurellosis, received 0, 1, or 2 vaccine doses. mild, transient lameness in most bighorns 1 day after initial vaccination was the only adverse effect observed. oropharyngeal (> or = 75%) and ...19979391957
an outbreak of pasteurella multocida pneumonia in lambs during a field trial of a vaccine against pasteurella haemolytica.a vaccine against pneumonic pasteurellosis was evaluated for efficacy at two dilutions in lambs transported by sea from new zealand to saudi arabia. the experimental vaccine was a killed pasteurella haemolytica serotype a1 and a2 preparation. there was no evidence of either dilution of the vaccine leading to a lower pneumonia death or lesion rate than for the control group. however, bacteriological examinations to establish the causality of the pneumonia cases showed pasteurella multocida to be ...199716031950
comparison of serologic and protective responses induced by two pasteurella vaccines.vaccine development for the prevention of pneumonic pasteurellosis remains a critical issue for the feedlot industry. most currently available pasteurella vaccines are formulated to stimulate immunity by either providing an adequate antigenic mass in the administered dose, or by relying on subsequent production of antigens by in vivo growth of live organisms. the ability of these different types of vaccines to stimulate rapid and high titres to key antigens is a key factor that will influence su ...19989684046
pasteurella haemolytica complicated respiratory infections in sheep and goats.respiratory infections which commonly occur in sheep and goats often result from adverse physical and physiological stress combined with viral and bacterial infections. inevitably, pasteurella haemolytica pneumonia occurs as a result of these interactions. in this review, we present recent advances in research on the complex etiology of pneumonia involving p. haemolytica. initially stress, induced by factors such as heat, overcrowding, exposure to inclement weather, poor ventilation, handling an ...19989689740
the biphasic mrna expression pattern of bovine interleukin-8 in pasteurella haemolytica lipopolysaccharide-stimulated alveolar macrophages is primarily due to tumor necrosis factor alpha.pasteurella haemolytica serotype 1 is the bacterial agent responsible for the pathophysiological events associated with bovine pneumonic pasteurellosis. our previous studies support a role for the lipopolysaccharide (lps) from p. haemolytica in the induction of proinflammatory cytokines. one of the pathological hallmarks of bovine pneumonic pasteurellosis is an influx of neutrophils into the alveolar spaces. this pronounced influx suggests the local production of a chemotactic factor(s) such as ...19989712752
proliferative responses of peripheral blood leucocytes of sheep infected with trypanosoma evansi.the effects of trypanosoma evansi on the proliferative responses of ovine peripheral blood leucocytes (pbl) were examined in in vitro cell culture systems. sheep were vaccinated against pneumonic pasteurellosis with a monovalent pasteurella haemolytica vaccine and then infected with t. evansi treu 2143. from 1 week post-infection (p.i.), the pbl were separated and stimulated in cultures with either concanavalin a (con a), bacterial lipopolysaccharide (lps), pasteurella antigen (p.ag), or homolog ...19989716108
increase in cd5+ b cells and depression of immune responses in sheep infected with trypanosoma evansi.the effects of trypanosoma evansi on the cellular and humoral immune responses of sheep to pasteurella haemolytica vaccine were studied. peripheral blood lymphocytes (pbls) from the sheep were analysed using single and double-colour indirect immunofluorescence staining and flow cytometry to monitor changes in circulating b and t cell subsets. serum antibody responses were assayed using the enzyme-linked immunosorbent assay technique (elisa), in addition to measuring local skin reactions at the s ...19989656456
occurrence of autoantibodies to cilia in lambs with a 'coughing syndrome'.a respiratory disease of lambs that has been termed the 'coughing syndrome' has been observed in the mid-western region of the united states of america. mycoplasma ovipneumoniae (m. ovipneumoniae) and mycoplasma arginini (m. arginini) were routinely isolated from the respiratory tract of lambs with this disease. a high level of antibodies reactive with ovine cilia of the upper respiratory tract was detected in the sera from many of the lambs in affected flocks but not in sera of lambs from unaff ...19989730216
discrimination between apo and iron-loaded forms of transferrin by transferrin binding protein b and its n-terminal subfragment.many pathogens of the pasteurellaceae and neisseriaceae possess a surface receptor that binds transferrin (tf) as an initial step in an iron acquisition process. this receptor is comprised of two proteins, transferrin binding protein a (tbpa) and transferrin binding protein b (tbpb). since the ability to recognize the iron-loaded form of tf preferentially would be a useful attribute of these receptors, we examined this property in a number of bacterial species. in solid-phase binding assays with ...19989817820
genetic and immunologic analyses of plpe, a lipoprotein important in complement-mediated killing of pasteurella haemolytica serotype 1.pasteurella haemolytica serotype 1 is the bacterium most commonly associated with bovine shipping fever. the presence of antibodies against p. haemolytica outer membrane proteins (omps) correlates statistically with resistance to experimental p. haemolytica challenge in cattle. until now, specific p. haemolytica omps which elicit antibodies that function in host defense mechanisms have not been identified. in this study, we have cloned and sequenced the gene encoding one such protein, plpe. anal ...19989826333
target cell specificity of the pasteurella haemolytica leukotoxin is unaffected by the nature of the fatty-acyl group used to activate the toxin in vitro.the leukotoxin (lkta) of pasteurella haemolytica is active only against cells of ruminant origin. it is synthesised as an inactive protoxin encoded by the lkta gene and post-translationally modified to the active toxin by the product of the lktc gene. the lkta and lktc proteins were expressed separately in escherichia coli and partially purified. active lkta was produced in vitro in the presence of lktc and acyl-acyl carrier protein (acp) charged separately in vitro with a fatty-acyl group. the ...19989851045
the pasteurella haemolytica 35 kda iron-regulated protein is an fbpa homologue.in a previous investigation, a 35 kda iron-regulated protein was identified from total cellular proteins of pasteurella haemolytica grown under iron-depleted conditions. this study reports identification of the gene (fbpa) encoding the 35 kda protein based on complementation of an enta escherichia coli strain transformed with a plasmid derived from a p. haemolytica lambda zap ii library. cross-reactivity was demonstrated between an anti-35 kda mab and a 35 kda protein expressed in this strain. f ...19989884235
cd34 molecule epitope distribution on cells of haematopoietic origin.the cd34 molecule belongs to the mucin membrane molecule family and is expressed on virtually all normal haematopoietic progenitor cells (hpc). due to its heavy glycosylation, several different epitopes exist on the molecule. based on the sensitivity of the glycosylated molecule to degradation with a glycoprotease from pasteurella haemolytica and neuraminidase, three classes of epitopes have been identified. the class i and ii epitopes are probably related to the glycosylated part of the molecul ...19989669673
in vivo production of neuraminidase by pasteurella haemolytica in market stressed cattle after natural infection.pasteurella haemolytica (ph) is the most important cause of the bovine acute fibrinohemorrhagic pneumonia that occurs in market stressed calves after shipment to feedyards. recent characterization of neuraminidase production by these organisms has shown that all 16 serotypes produce an immunologically similar form of the enzyme. anti-neuraminidase antibody against pha1 and pha6 was determined in 101 2- to 5-month-old calves, on their farms of origin, at the order buyer barn (obb), and through 28 ...19989732530
the clinical efficacy of enrofloxacin in the treatment of experimental bovine pneumonic pasteurellosis.the clinical efficacy of enrofloxacin was tested in calves with experimentally induced pneumonic pasteurellosis. a strain of pasteurella haemolytica, biotype a, serotype 1 (p. haemolytica a1), which had been isolated from an outbreak of pneumonic pasteurellosis in feedlot calves, was used to induce the disease in 24 eight-month-old calves. each animal received, by intratracheal injection, 6 x 10(11) colony forming units of p. haemolytica a1 in a four-hour log phase culture. twelve similar animal ...19989741054
the association of titers to haemophilus somnus, and other putative pathogens, with the occurrence of bovine respiratory disease and weight gain in feedlot calves.serum samples were obtained from 602 calves (from 19 groups in four feedlots: three in ontario, and one in alberta) upon arrival at the feedlot and 28 d later. of these calves, 202 developed bovine respiratory disease (brd) and 400 did not develop brd. based on high antibody titers noted upon arrival, we infer that most calves were exposed to haemophilus somnus prior to arrival at the feedlot. within a group, calves with high titers on arrival had a reduced risk of developing brd later. most cal ...19989798091
anti-inflammatory benefits of tilmicosin in calves with pasteurella haemolytica-infected lungs.to determine whether tilmicosin alters neutrophil infiltration or function, induces neutrophil apoptosis, and affects accumulation of leukotriene b4 (ltb4) or tumor necrosis factor-alpha (tnf-alpha) in lungs of calves experimentally infected with pasteurella haemolytica.19989622749
isolation of a nicotinamide-adenine dinucleotide (nad)-dependent pasteurella haemolytica-like organism from the placenta of an aborted cow. 19989711392
pasteurella haemolytica leukotoxin-induced increase in phospholipase a2 activity in bovine neutrophils.exposure of bovine neutrophils to pasteurella haemolytica leukotoxin (lkt) stimulates the production of leukotriene b4 (ltb4), which is believed to be an important chemotactic agent in the development of acute fibrinopurulent pneumonic infection in cattle. the involvement of phospholipase a2 (pla2) in lkt-induced synthesis of ltb4 was studied by using bovine neutrophils labeled with 3h-arachidonate ([3h]aa). incubation of isolated neutrophils with [3h]aa resulted in incorporation of radioactivit ...19989573065
role of sialosyl lewis(a) in adhesion of colon cancer cells--the antisense rna approach.to study whether the adhesion of colon cancer cells to e-selectin can be directly affected by changes in the expression level of sialosyl le(a) antigen we created a specific loss-of-function phenotype. a stable subclone (cx-1.1) with high expression of sialosyl le(a) structure, obtained from a heterogenous population of colon carcinoma cx-1 cells, was transfected with an expression vector containing a fragment of cdna for alpha1,3/4-fucosyltransferase in antisense orientation. after transfection ...19989578490
in vivo effect of pasteurella haemolytica infection on bovine neutrophil morphology.to determine whether characteristic changes in neutrophil morphology caused in vitro by pasteurella haemolytica leukotoxin (lkt) can be observed in vivo by electron microscopic examination of infected tissue chamber fluids and pneumonic lungs.19989582961
problems of identification in clinical microbiology exemplified by pig bite wound infections.our experience from attempts to identify bacteria isolated from boar bite/gore wounds is the background for a discussion of identification problems. some organisms, although not very common or well-known, can be identified when using commercial kits or conventional methods, provided they are sufficiently characterized, as exemplified by pasteurella aerogenes isolated from cases 1 and 2. some organisms may be wrongly identified, or not identified, by both commercial kits and conventional methods, ...19989987187
characterization of a 54-kda heat-shock-inducible protein of pasteurella haemolytica.growth-condition-dependent antigens play a role in the virulence or protective capacity of many organisms. enhanced production of an approximately 54-kda protein was detected in heat-shocked cultures of pasteurella haemolytica. the heat-shock-inducible protein cross-reacted with antibodies to 60-kda heat-shock proteins of mycobacterium tuberculosis, chlamydia, and escherichia coli groel. a probe containing the e. coli groel operon hybridized with fragments of p. haemolytica chromosomal dna on so ...19989595628
membrane protein proteolysis assayed by fluorescence quenching: assay of o-sialoglycoprotein endopeptidase.the assay of the o-sialoglycoprotein endopeptidase of pasteurella haemolytica has previously used the cleavage of 125i-labeled glycophorin a, measured by sds-page, autoradiography, gel-slicing, and scintillation counting. a new assay is based on the increased fluorescence which results from proteolytic cleavage of a fluorescence-quenched micellar substrate, 4,4-difluor-5,7-dimethyl-4-bora-3 alpha, 4 alpha-diaza-s-indacene-3-propionic acid conjugated to glycophorin a (bodipy-fl-glycophorin a). mi ...19989606137
bovine platelet adhesion is enhanced by leukotoxin and sialoglycoprotease isolated from pasteurella haemolytica a1 cultures.platelet and fibrin deposits are among characteristic changes observed in lung alveoli of cattle with pasteurellosis induced by pasteurella haemolytica (biotype a, serotype 1). to determine whether the platelet function could be directly affected by protein products produced by the bacterium, the effects of leukotoxin and o-sialoglycoprotease, culture supernatant antigen secreted by pasteurella haemolytica a1, on bovine platelet activation were examined by evaluating the enhancement of platelet ...19989646468
high-performance liquid chromatography of pasteurella haemolytica leukotoxin using anion-exchange perfusion columns.an exotoxin, called leukotoxin (lkt), from pasteurella haemolytica, which had previously proved difficult to purify, was purified by high-performance liquid chromatography using rigid highly hydrophilic microparticulate anion-exchange columns. these anion-exchange stationary phases were employed to overcome difficulties of the relatively hydrophobic lkt interacting with dextran or styrene-based resins. while a short non-porous deae column allowed the partial microscale purification of the leukot ...19989652117
biochemical conditions for the production of polysialic acid by pasteurella haemolytica a2.the capsular polysaccharide of pasteurella haemolytica a2 consists of a linear polymer of n-acetylneuraminic acid (neu5ac) with alpha(2-8) linkages. when the bacterium was grown at 37 degrees c for 90 h in 250 ml shake flasks at 200 rpm in brain heart infusion broth (bhib), it accumulated, attaining a level of 60 microg/ml. release of this polymer was strictly regulated by the growth temperature, and above 40 degrees no production was detected. the pathway for the biosynthesis of this sialic aci ...199810052589
molecular and biochemical mechanisms of pasteurella haemolytica leukotoxin-induced cell death.pasteurella haemolytica leukotoxin (lkt) is a member of the rtx family of pore-forming toxins that kill bovine immune cells. several studies have suggested that rtx toxins kill target cells by the induction of apoptosis. in the present study, bl3 bovine leukaemia cells were exposed to lkt and assessed by molecular and flow cytometric techniques that measure different aspects of apoptotic cell death. the intoxicated cells demonstrated morphological, light scatter and hoechst 33258 staining charac ...19989895270
serologic responses of young colostrum fed dairy calves to antigens of pasteurella haemolytica a1.the potential and limitations of early calfhood vaccination to induce active immunity to pasteurella haemolytica a1 in conventional colostrum fed calves were investigated. holstein dairy calves (n = 29) were vaccinated at 2 and 4 weeks of age, or at 6 and 8 weeks of age with a commercial culture supernatant vaccine (presponse, langford inc., guelph, ont., canada), or remained unvaccinated as controls. serum antibody titres were measured using an indirect bacterial agglutination assay, a leukotox ...19989796059
induction of cd4+cd8+ double positive t cells and increase in cd5+ b cells in efferent lymph in sheep infected with trypanosoma evansi.the effects of trypanosoma evansi on efferent lymphocyte phenotypes draining from a lymph node primed with pasteurella haemolytica vaccine were studied in sheep. the prefemoral efferent lymphatic ducts of the infected sheep along with those of two uninfected sheep were surgically cannulated. lymph was collected and lymphocytes recovered from it analysed by two-colour indirect immunofluorescence staining and cytofluoremetry in a fluorescence activated cell analyser (facscan). the study showed the ...19989568615
assessment of spatial and temporal clustering of ampicillin- and tetracycline-resistant strains of pasteurella multocida and p haemolytica isolated from cattle in california.to determine whether ampicillin- and tetracycline-resistant strains of pasteurella multocida and p haemolytica isolated from california cattle with pneumonia were spatially and temporally clustered and to compare overall estimates of percentages of these isolates resistant to these antimicrobials with estimates obtained on the basis of regional and temporal information.19989540872
cross-protection studies with three serotypes of pasteurella haemolytica in the goat model.cross-protection studies employing three serotypes of pasteurella haemolytica (ph) were performed in goats, with challenge exposure by transthoracic injection. indirect hemagglutination (iha) serum titers showed that the herd had been naturally infected with ph biovar a, serovar 2 (pha2) prior to the study. sixty-four weanling male spanish goats were randomly allotted to 16 groups. fifteen goats were given two transthoracic injections into the lungs 21 days apart with live pasteurella haemolytic ...19989504986
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