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1.
Virulence factors were studied in 82 strains of Escherichia coli isolated from the urine of dogs with urinary tract infections. The most frequently expressed O antigens were 2, 4, 6, 25, and 22/83. Most strains were K nontypeable. Mannose-sensitive hemagglutination (MSH) with canine erythrocytes was observed in 71 strains and mannose-resistant hemagglutination (MRH) was observed in 32 strains. Strains that caused MSH of erythrocytes from dogs also caused MSH of erythrocytes from guinea pigs. Most strains that caused MRH of human A1P1 erythrocytes also reacted with erythrocytes of dogs. Of 22 strains (27%) that agglutinated human A1P1 erythrocytes, but not A1p erythrocytes, 17 (77%) had specificity for globo A, but did not react with the galactose alpha 1----4galactose beta disaccharide receptor. The remaining 5 strains and 2 others that simultaneously expressed an X adhesin agglutinated galactose alpha 1----4galactose beta-coated latex beads. Bacterial adherence to canine uroepithelial cells from the bladder was most often observed in strains expressing MSH, less often observed in strains expressing MRH, and least often observed in strains that failed to induce hemagglutination. Adherence of MSH strains to canine uroepithelial cells was inhibited by alpha-methyl-D-mannoside. As a group, MRH strains expressing globo-A- and galactose alpha 1----4galactose beta-specific adhesins did not have strong adherence. Strains of E coli isolated from dogs with urinary tract infections most commonly expressed type-1 fimbriae, and the main mechanism of in vitro adherence to canine uroepithelial cells involved a mannose-sensitive mechanism. Overrepresentation of globo-A-specific adhesins did not appear to be related to adherence of canine uroepithelial cells.  相似文献   

2.
Adherence of Moraxella bovis to cell cultures of bovine origin   总被引：5，自引：0，他引：5  
The adherence of five strains of Moraxella bovis to cell cultures was investigated. M bovis adhered to cultures of bovine corneal epithelial and Madin-Darby bovine kidney cells but not to cell types of non-bovine origin. Both piliated and unpiliated strains adhered but piliated strains adhered to a greater extent than unpiliated strains. Antiserum against pili of one strain inhibited adherence of piliated strains but caused only slight inhibition of adherence to the unpiliated strains. Treatment of bacteria with magnesium chloride caused detachment of pili from the bacterial cell and markedly inhibited adherence of piliated strains but caused only slight inhibition of adherence by the unpiliated strains. The results suggested that adhesion of piliated strains to cell cultures was mediated via pili but that adhesins other than pili may be involved in the attachment of unpiliated strains of M bovis to cells.  相似文献   

3.
Chicken pathogenic Escherichia coli strains were found to autoagglutinate in a static culture of trypticase soy broth (TSB). One strain, designated PDI-386, was further studied for its autoagglutinating property. Acidity in the cultured medium caused by glucose degradation induced the autoagglutination. The bacterial cells grown in a glucose-free L-broth could be aggregated by adding acid, which suggests a potentiality of autoagglutination of the strain grown in the L-broth. The autoagglutinating parent (Agg) formed small colonies with irregular edges like rough colonies on the TS agar, whereas its non-autoagglutinating variant (Nag) formed larger smooth colonies with a perfectly round edge. The Nag colony was easily generated from the Agg colony on the TS agar. The autoagglutinating property was very unstable when the bacteria was passed in the TSB, but rather stable in the L-broth. Under electron microscope, the Agg were found to possess pili of more than 20 microns in length. However, the phenotypic expression of autoagglutination did not correlate with that of mannose-sensitive hemagglutination against guinea pig erythrocytes. Incubation of the Nag in the L-broth at room temperature for more than 10 days provoked the reversion of the autoagglutination. There was no difference between the Agg and the Nag in terms of surface hydrophobicity, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of membrane proteins and LPS, and plasmid profiles. The virulence of the Agg was higher than that of the Nag. The autoagglutination property is, however, so unstable that the pathogenicity of E. coli isolates from chickens should be carefully evaluated.  相似文献   

4.
On a cattle farm latently infected by M. bovis, field studies aiming at the formation of a mycoplasma free herd, were carried out with a group of newborn female calves. These calves were strictly separated from their dams and any other cattle immediately after parturition. Intensive investigations for mycoplasmas were made over 30 months (mycoplasma isolation from nasal swabs, antibody detection by means of indirect hemagglutination test and ELISA technique). M. bovis could never be isolated from the samples. Also, there were no antibodies to M. bovis. In some animals antibody titers to M. bovis occurred after having contact with cattle infected with M. bovis. The results demonstrate a practicable way to establish cattle herds free from M. bovis infection.  相似文献   

5.
79 strains of P. multocida were investigated, mostly isolated from porcine nasal cavities, and a mannose-resistant hemagglutination with guinea pig and human group 0, but not with porcine erythrocytes was found. Fimbriae as adhesins were demonstrated only on 2 strains. A correlation between capsular type, hemagglutination, fimbriation and toxigenicity on the examined P. multocida strains was not observed. Three strains were investigated for the adherence to the nasal mucosa of neonatal pigs; aggregates shown by scanning electron microscopy indicate colonization; a correlation of adherence with surface proteins and slime production of P. multocida is discussed.  相似文献   

6.
Calves from five Ontario feedlots were bled on arrival and approximately 28 days later. Calves treated during this interval for undifferentiated respiratory disease were classified as cases and untreated calves were classified as controls. Serum was titrated blindly for antibodies to Mycoplasma bovis and Mycoplasma dispar. Indirect hemagglutination titers of 1:20 or more were assumed to reflect recent or current exposure, whereas 1:10 or less were not. The titers to M. bovis increased in all feedlots indicating active infection. The initial titers to M. dispar were higher than the titers against M. bovis, yet they increased in all feedlots except one, suggesting widespread infection with this organism. There was an increased risk (although not statistically significant) of being treated if the titer against M. bovis rose during the period. Calves with low M. dispar titers on arrival were at increased risk of being treated and titer increases were strongly associated with treatment (statistically significant). Thus, the serological results indicate high prevalence of M. bovis and M. dispar in the feedlot calves and that calves with increasing titers in particular to M. dispar are at increased risk of being treated for respiratory disease.  相似文献   

7.
Twelve freshly lactating ewes were experimentally infected with 2 Mycoplasma (M.) bovis strains via the teat canal in the left udder. The M. bovis infection produced a febrile clinical mastitis in all infected animals. M. bovis could be re-isolated regularly from the experimentally infected udder halves and the infection spread to the other halves. Some contact animals and 4 suckling lambs became naturally infected. Antibody titres were detected by means of the indirect hemagglutination test in blood sera 2 to 3 weeks post infectionem. The pathological lesions were similar to those of the M. bovis mastitis of cows. By the end of the trial the ewes had recovered from the clinical mastitis.  相似文献   

8.
The presence and type of adhesins occurring in Pseudomonas aeruginosa strains were determined by hemagglutination test with a 3% suspension of normal and trypsin-treated human group A erythrocytes, with or without the addition of sugar inhibitors (D-mannose, D-glucose, L-fucose, D-galactose, D-fructose, lactose, N-acetylneuraminic acid, N-acetylglucosamine and N-acetylgalactosamine). This study showed that a low percentage of Pseudomonas aeruginosa strains caused the agglutination of normal erythrocytes. Trypsin treatment of erythrocytes did not affect the hemagglutinating properties, indicating that hemagglutination was not dependent upon a trypsin-sensitive protein on the erythrocytes surface. Most of the studied strains agglutinated RBCs at 37 degrees C. A great variability in the inhibiting activity on studied strains was observed among the carbohydrates tested. These results demonstrated the predominant role of N-acetylglucosamine, N-acetylgalactosamine and N-acetylneuraminic acid for Pseudomonas aeruginosa adhesion to RBCs.  相似文献   

9.
The ability of Mycoplasma hyopneumoniae to agglutinate RBC was evaluated to develop an in vitro cytadsorption assay. Using swine RBC in a microtitration hemagglutination test, no agglutination or partial agglutination was detected. Comparison of RBC from various other species indicated that improved hemagglutination was obtained with RBC from turkeys. This hemagglutination was detected only when mycoplasma cells used in the assay had been frozen and thawed, heated at 50 C for 30 minutes, or treated with trypsin. Treatment of RBC with trypsin or neuraminidase enhanced hemagglutination. Possible surface lectin activity in M hyopneumoniae was evaluated by use of carbohydrates in a blocking assay; hemagglutination was not inhibited by any of 13 carbohydrates evaluated. Mycoplasma hyopneumoniae convalescent porcine serum and monoclonal antibodies against 2 M hyopneumoniae immunogens of molecular weights of 64,000 and 41,000 inhibited hemagglutination.  相似文献   

10.
The binding and hemagglutinating properties of cholera toxin (CT) were studied by competitive binding assays and hemagglutination inhibition. The binding of 125I-labeled CT to neuraminidase-treated human type B erythrocytes was most effectively inhibited by ganglioside GM1 among different inhibitors used. Other mono-, di-, and polysaccharides and glycoproteins were at least 10(5) times less potent inhibitors. On the other hand, hemagglutination of neuraminidase-treated human type B erythrocytes by CT was inhibited by lactose, galactose, hog A + H, bovine salivary mucin, porcine thyroglobulin, and fetuin, whereas that was not effectively inhibited by ganglioside GM1 at the highest concentration. These findings suggest that the predominant binding substance for CT on human type B erythrocytes is ganglioside GM1 and that hemagglutination requires some additional process since the interaction of CT with ganglioside GM1 is somehow different in hemagglutination.  相似文献   

11.
The binding specificity of pertussis toxin (PT) was compared with lectins with well-defined specificities by hemagglutination, hemagglutination inhibition and competitive binding assays. Neuraminidase-treated human erythrocytes were much less weakly agglutinated by PT than untreated ones. Hemagglutination of untreated human type A erythrocytes by PT was inhibited by fetuin, haptoglobulin and hog A + H. Mono- and disaccharides, and N-acetylneuraminic acid alone were ineffective at the highest concentrations used. On the other hand, hemagglutination by Ricinus communis agglutinin (RCA-1) was effectively inhibited by these substances. Similar results were also obtained in competitive binding assays with 123I-labeled PT and untreated type A erythrocytes. The binding of 125I-labeled PT to type A erythrocytes was not effectively inhibited by any of lectins with well-defined specificities. These results suggest that the combining site of PT may be specific for terminal sialic acid and/or sialic acid-linked carbohydrate portion(s) which can not be recognized by lectins reported previously.  相似文献   

12.
The adherence of viable and heat-treated Mycoplasma bovis to bovine peripheral blood neutrophils was studied by specific immunofluorescence staining and flow cytometry. Viable and heat-treated M. bovis cells, adhered to bovine neutrophils in dose-dependent fashion within a 30 min incubation. Fluorescence quenching using crystal violet indicated that unopsonized M. bovis cells remained on the surface of bovine neutrophils without experiencing significant ingestion. The effect of M. bovis adherence on neutrophil microbicidal function was examined by measuring luminol enhanced chemiluminescence (CL). Adherent M. bovis cells did not elicit a bovine neutrophil CL response over a 75 min incubation period. M. bovis inhibited the capacity of bovine neutrophils to mount a CL response. Inhibition occurred whether viable or heat-treated M. bovis cells were used and it occurred when neutrophils were stimulated with opsonized zymosan (OZ) or phorbol myristate acetate (PMA). Inhibition of the PMA stimulated neutrophil CL response required cytadherence by M. bovis cells. These findings suggest that activation of the bovine neutrophil respiratory burst was inhibited at or distal in the pathway to the activation of protein kinase C (PKC), the site of PMA stimulation, and that it was mediated by a direct interaction between the adhering M. bovis cells and the bovine neutrophil membrane.  相似文献   

13.
Mycoplasma bovis is known to be responsible for pneumonia and arthritis in calves, as well as mastitis in dairy cows. Despite clear evidence of its pathogenic potential, little is known about mechanisms of cytadherence and the molecular factors involved. The purpose of this work was to compare adherence rates of M. bovis field strains to different host cell lines and study the effects of cloning and sub-culturing M. bovis strains on their adherence properties. Eighteen metabolically labeled M. bovis strains isolated from different pathological backgrounds were examined in adherence trials using four different host cell lines, i.e. embryonic bovine lung (EBL), embryonic bovine trachea (EBTr), Madin Darby bovine kidney (MDBK) and rabbit kidney (RK) cells. Although large interstrain variations in adherence rates (3.4-19.1%) were measured they could not be correlated to the pathological background (pneumonia, arthritis or mastitis). Adherence rates to the fibroblast cell line (EBTr) were significantly lower than those to the three epithelial cell lines (EBL, MDBK and RK). The only non-pathogenic strain (221/89) exhibited lower adherence rates than three isolates from clinical mastitis. Interestingly, adherence rates were significantly reduced after in vitro passaging. In contrast, no effect of single cloning of strains on adherence was observed. There was no general correlation between expression of variable surface proteins (Vsps) as monitored by immunoblotting and adherence rates, although alterations in Vsp expression profiles were seen as a consequence of passaging. As there is probably a large number of adhesins, variable and non-variable, on the surface of M. bovis cells the issue is very complex, and the most active components have yet to be identified.  相似文献   

14.
Most of 82 F165-positive Escherichia coli isolated from calves and piglets with diarrhea or septicemia and possessing pap related sequences caused mannose-resistant, neuraminidase-resistant hemagglutination of human and bovine erythrocytes. Less than half of these isolates demonstrated binding specificity for the alpha-D-galactosyl-(1-4)-beta-D-galactopyranose or galactose-N-acetyl-alpha-(1-3) galactose-N-acetyl moieties recognized by P and F (or Prs) adhesins respectively. Binding specificity for the galactose-N-acetyl-alpha-(1-3) galactose-N-acetyl moiety was associated with isolates causing septicemia in newborn piglets.  相似文献   

15.
Forty-nine avian pathogenic Escherichia coli (APEC) strains obtained from chickens suffering from septicemia (24), swollen head syndrome (14) and omphalitis (11), isolated from individuals in different regions of Brazil and from different outbreaks, were studied for their adhesion to trachea epithelial cells, fimbrial expression and hemagglutination capacity to different erythrocyte types. These results were compared with their content of fimbriae-related genes as detected by polymerase chain reaction (PCR) using specific pair of primers. The aim of these assays was to determine the importance of expression of adhesins in the pathogenic strains and to evaluate the presence of adhesin genes either previously described or not yet recognized for APEC strain. Thirty commensal strains isolated from poultry showing no signs of any of the above diseases were used to compare the results with the pathogenic isolates. The PCR assay demonstrated that septicaemic and swollen head syndrome strains had the highest number of adhesion-related genes of recognized importance in pathogenicity. Using different media for growth conditions, 40 different D-mannose resistant haemagglutination patterns were observed in this study, what indicates the expression of a great variability of surface agglutinins in these bacterial strains. Our results also showed that adhesion, whether D-mannose resistant (MRA) or D-mannose sensitive (MSA), is a characteristic observed in both pathogenic and commensal strains. Several strains with positive adherence had no genetic sequences related to the studied adhesin genes what indicates that our APEC strains probably possess a genome with adhesins genes besides those describe elsewhere and that have not yet been described.  相似文献   

16.
Stable mycoplasma antigens for the indirect hemagglutination test (IHA) were prepared employing glutaraldehyde treated sheep erythrocytes sensitized with Mycoplasma agalactiae subsp. bovis and Mycoplasma bovigenitalium antigens. Employing these antigens mycoplasma antibodies were detected in sera from cattle which had mastitic symptoms due to natural infection with either M. agalactiae subsp. bovis or M. bovigenitalium. A total of 200 cows from four herds were examined at varying intervals for the presence of M. agalactiae subsp. bovis and for the detection of antibody using growth inhibition and IHA tests. Mycoplasmas were isolated from 37 animals. Growth inhibiting antibody was detected from 56 of the 200 animals. In the IHA tests, antibody titer greater than or equal to 1:80 were detected in 148 animals, 76 of these having antibody titers greater than or equal to 1:160, while sera of 116 normal control animals had no growth inhibiting antibody and none had IHA antibody titers greater than 1:40. M. bovigenitalium was isolated from the milk of three of 26 animals in a fifth herd during an outbreak of mastitis. Growth inhibiting antibodies were demonstrated in the sera of ten of the 26 animals. However, the IHA test detected antibody titers of greater than or equal to 1:160 in 13 animals and of 1:80 in one of the 26 animals. To determine the specificity of the IHA tests, M. agalactiae subsp. bovis and M. bovigenitalium antigens were reacted with rabbit hyperimmune typing sera produced against 12 species of bovine mycoplasmatales. Homologous antisera showed IHA antibody titers of 1:1280 and 1:2560 against M. agalactiae subsp. bovis and M. bovigenitalium respectively, whereas heterologous antisera showed IHA antibody titers of less than or equal to 1:20. Also eight type-specific bovine antisera were reacted with M agalactiae subsp. bovis and M. bovigenitalium antigens in homologous and heterologous tests. Homoogous reactions showed IHA antibody titers greater than or equal to 1:320, whereas heterologous reactions showed IHA titers of less than or equal to 1:20. This IHA test promises to be useful for the detection of bovine mycoplasma antibodies in sera from cattle infected with M. agalactiae subsp. bovis or M. bovigenitalium. Thes test is sensitive, reproducible and specific and the technique is relatively simple and rapid. The antigens were stable for at least seven months.  相似文献   

17.
Objective : To investigate the associations between Coombs’ testing, haemoplasma and retroviral infections, and feline anaemia. Methods : Haematology, Coombs’ testing (including assessment of persistent autoagglutination) and selected infection testing (haemoplasma, feline leukaemia virus/feline immunodeficiency virus provirus) were performed in blood samples collected from 60 anaemic and 60 non-anaemic cats. Results : No association between infection and anaemia or Coombs’ positivity existed. Anaemic cats (21.7%) were significantly more likely than non-anaemic cats (0%) to have cold autoagglutination (P<0.0001), but significance (set at ≤0.0025 due to multiple testing) was not quite reached when Coombs’ positivity was compared between anaemic (40.4% and 21.7% positive at 4°C and 37°C, respectively) and non-anaemic (20% and 3.3% positive, P=0.021 and P=0.004, at 4°C and 37°C, respectively) cats. Cats with immune-mediated haemolytic anaemia were significantly more likely to have persistent cold autoagglutination (P<0.0001) and be Coombs’ positive at 37°C with polyvalent (P<0.0001), immunoglobulin (Ig)G (P<0.0001) or any antiserum (P<0.0001). Haemoplasmas and retroviruses were uncommonly detected. Clinical Significance : Cats suspected of having immune-mediated haemolytic anaemia should be evaluated for persistent autoagglutination at 4°C as well as performing Coombs’ testing at 37°C, but positive results may occur in with other forms of anaemia. Testing for erythrocyte-bound antibodies should always be interpreted in parallel with documentation of haemolysis in anaemic cats.  相似文献   

18.
OBJECTIVE: To characterize the effect that filtrate obtained from cultures of Moraxella bovis has on cultured corneal epithelial cells and other types of cultured mammalian cells. SAMPLE POPULATION: Cultured hamster corneal epithelial cells, bovine epithelial cells, and several transformed cell lines exposed to culture filtrate from a pathogenic isolate of M bovis. PROCEDURE: Moraxella bovis was cultured, and bacteria were removed by filtration. The resulting bacterial culture filtrate was incubated with various types of cultured cells, and effects of the filtrate on detachment of various mammalian cell types was quantified by the use of neutral red dye. Additionally, bacterial culture filtrate was treated with protease inhibitors as well as trypsin and heat prior to incubation with cultured mammalian cells. RESULTS: Bacterial culture filtrate of M bovis caused all types of cultured cells to detach from each other and from the substrate, with the maximal effect evident 2 hours after initiating incubation. Detached cells were alive, and detachment was reversible. Serine protease inhibitors (phenylmethylsulfonylfluoride and alpha2-macroglobulin) inhibited cell detachment attributable to bacterial culture filtrate. Heating and treatment with trypsin also inhibited cell detachment. CONCLUSIONS AND CLINICAL RELEVANCE: Moraxella bovis produces a soluble factor that causes reversible detachment of cultured cells. This activity may play a role in the pathogenesis of infectious bovine keratoconjunctivitis.  相似文献   

19.
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20.
The cytotoxicity of Moraxella bovis whole cells and culture filtrates was studied, using 51Cr-labeled bovine and human blood neutrophils. The cytotoxicity of living M bovis was directly related to the concentration of bacteria in the neutrophil cultures, and was maximal at an approximate neutrophil to bacteria ratio of 1:10. Cytotoxicity was maximal by 30 minutes after living bacteria were added to the suspension of the 51Cr-labeled neutrophils. Expression of the cytotoxicity was dependent on the presence of Ca2+ in the media, and was independent of the presence of Mg2+. Cytotoxic activity was eliminated by inactivating M bovis in buffers containing formalin or sodium azide. Hemolytic and nonhemolytic isolates of M bovis were examined for cytotoxic activity. All 7 of the hemolytic isolates were cytotoxic for bovine neutrophils, but all 4 of the nonhemolytic isolates were devoid of cytotoxic activity. None of the 11 isolates were cytotoxic for human neutrophils. Sterile filtrates from 6-hour shaker cultures of a hemolytic M bovis isolate were cytotoxic for bovine neutrophils. Cytotoxicity of the filtrate was eliminated by heating, incubation with trypsin, or addition of EDTA to the media. Bacterial homogenates or sterile filtrates prepared from statistically incubated cultures of M bovis were not toxic for bovine neutrophils.  相似文献   

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