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1.
Antibody against Aeromonas salmonicida was detected in sera from immunised or experimentally infected rainbow trout by enzyme-linked immunosorbent assay (ELISA) using the biotin-avidin system. The ELISA titre correlated well with the agglutinin titres of the sera, but the ELISA was found to be more sensitive than the agglutination test. When the rainbow trout serum was separated by column chromatography, antibody activity (determined by ELISA and agglutination test) was detected in the IgM fractions. Minimum cross reaction was observed in the ELISA system between antigen prepared from A salmonicida and antibodies against Vibrio species and other species of Aeromonas. The specificity of the ELISA was also confirmed by inhibition test. Immunisation of rainbow trout with a virulent strain of A salmonicida provided good protection, though no correlation was observed between the protection and the ELISA titres of sera.  相似文献   

2.
Characterization of antigens from mycoplasmas of animal origin   总被引：4，自引：0，他引：4  
Alcholeplasma laidlawii, Mycoplasma gallisepticum, M mycoides subsp mycoides, M agalactiae, M bovirhinis, mycoplasmal strain ST-6, and culture medium were compared with M bovis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme-linked immunosorbent assay (ELISA), and gel electrophoresis-derived ELISA. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated there were areas of homology and areas of heterology among the species tested. Sera from rabbits hyperimmunized with the mycoplasma organisms and noninoculated culture medium demonstrated ELISA reactivity with M bovis antigens immobilized on polystyrene. Absorption of the serum from a rabbit hyperimmunized with M bovis reduced 65.9% of its reactivity with culture medium, 29.7% to 32.7% of its reactivity with the heterologous species, and 21.1% of its reactivity with the homologous species. Gel electrophoresis-derived ELISA performed on immobilized M bovis antigens separated by molecular weight, using sera from rabbits hyperimmunized with the mycoplasmal species under study and noninoculated culture medium revealed antigenic components which are shared among species or with the culture medium and several components which may be unique to M bovis.  相似文献   

3.
Outer sheath antigen was prepared from Leptospira interrogans serovars pomona, sejroe and hardjo by treating the organisms with 1.0M NaC1 followed by 0.04% sodium dodecyl sulfate (SDS). Sodium dodecyl sulfate was removed from the SDS-protein complexes by the extraction of dodecyl sulfate anions as ion pairs with triethylammonium cations into an organic solvent. The outer sheath antigen was recovered from the organic solvent as a precipitate and used as the source of leptospiral enzyme-linked immunosorbent assay (ELISA) antigen. Utilizing this antigen, ELISA was adapted to detect bovine serum antibody to L. interrogans serovars pomona, sejroe and hardjo. The specificity of this assay in 344 bovine sera, which were negative in the microscopic agglutination test (MAT) for seven serovars, was 99.4%. In sera from 37 and 87 cattle which revealed MAT titers greater than or equal to 1:50 for L. interrogans serovars pomona and sejroe, the relative sensitivity of the test was 100%. The ELISA also showed a considerable degree of low level cross-reactivity with other serovars. Sixty-six (75.9%) out of 87 bovine sera which were MAT-positive (MAT titer of greater than or equal to 1:50) with serovars sejroe and hardjo only were ELISA positive with heterologous pomona antigen; 16 (43.2%) and six 16.2%) out of 37 bovine sera which were MAT positive MAT titer of greater than or equal to 1:50) with serovar pomona only were ELISA positive with heterologous sejroe and hardjo ELISA antigen respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

4.
Affinity-purified sheep IgG anti-chicken IgG horseradish peroxidase conjugate was utilized in an enzyme-linked immunosorbent assay (ELISA) to detect Mycoplasma gallisepticum- and M. synoviae-specific antibodies in chicken sera. Antigen, conjugate and substrate concentrations, and incubation times were adjusted to provide maximum differentiation between positive and negative sera. Use of phosphate-buffered saline containing 0.05% Tween 20 for washing and diluting steps and use of normal sheep serum to make the initial 1:10 serum dilution resulted in optimal differentiation between homologous and heterologous antisera. However, sera known to contain antibodies to M. gallisepticum or M. synoviae gave higher absorbance values with the heterologous antigen than did specific-pathogen-free sera. To reduce the frequency of nonspecific reactions to less than 2%, it was necessary to adjust the threshold absorbance for each antigen according to the known infectious status of the flock. Reproducibility of the assay was maintained by using positive and negative control sera on each plate. Results from 14.2% of the plates tested were rejected, because the endpoint of the positive control serum was more than one dilution from the most common value. Of four strains of M. gallisepticum used as antigens, none was clearly superior to the others in producing maximum titers with a range of M. gallisepticum antisera. However, nonspecific absorbance tended to be less with the S6 strain. The stability of M. gallisepticum-coated plates was maintained for up to 6 months at -8 C or below, whereas M. synoviae-coated plates were stored satisfactorily for 6 months at 4 C or below.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

5.
Specific antibody to Eperythrozoon ovis was detected by an enzyme-linked immunosorbent assay (ELISA) in the sera of infected sheep. In the presence of parasite antigen, positive control serum showed a reaction approximately eight times that of negative serum. When compared to an immunofluorescent antibody test (IFAT), the ELISA was eight times more sensitive. Positive control sera gave a titre of 1:3200 by IFAT and 1:25,600 by ELISA. Through the use of a reference titration curve ELISA could be used as a semi-quantitative system to determine antibody levels in test sera.  相似文献   

6.
The sensitivity of an indirect enzyme-linked immunosorbent assay (ELISA) for bovine IgG serum antibody to Pasteurella haemolytica was compared with that of an indirect hemagglutination (IHA) test. Pasteurella haemolytica serotypes were grown in a chemically defined cell culture medium, and soluble antigens released into the growth medium were used in the ELISA and IHA test. An ELISA with serotype-1 antigen consistently detected antibody in sera that were positive by IHA test (correlation, 99%). Sera reacting with serotype-1 ELISA antigens also reacted with ELISA antigens prepared from other serotypes. Although ELISA titers averaged 5 log2 units higher than IHA titers, plots of titers determined by the 2 methods were approximately linear. Titer increases detected in paired serum samples by either test were similar. The ELISA was more sensitive than was the IHA in detecting colostral IgG antibody in serum of newborn calves. The ELISA uses a simple, stable antigen preparation and detects antibody to P haemolytica serotypes that commonly infect cattle.  相似文献   

7.
An enzyme-linked immunosorbent assay (ELISA) for detecting antibody to Mycoplasma hyopneumoniae in porcine serum is described. The results are presented as an ELISA ratio, calculated by dividing the absorbance of the test sample by the mean absorbance of control negative sera. In known infected pigs, the ELISA ratio was highest when the serum concentration applied to the ELISA plate was diluted 1 in 20 in PBS - Tween. Mean ELISA ratios ranged from 1.2 +/- 0.3 for pigs without porcine enzootic pneumonia (PEP) lesions to 5.5 +/- 1.5 for pigs observed with a PEP lesion reacting positively with immunofluorescent histopathology. Pigs observed with typical PEP lesions at slaughter, but not confirmed by immunofluorescent histopathology had a mean ELISA ratio of 4.9 +/- 1.7. The ELISA was highly sensitive (95.6%) and specific (98.8%) when pig sera from commercial piggeries of known M hyopneumoniae infection status were assessed. No cross-reactivity with serum from a pig hyperimmunised with killed M flocculare was detected, and reactivity with serum from another pig hyperimmunised with killed M hyorhinis showed only weak cross-reactivity, which failed to reach the ELISA positive threshold (ELISA ratio 3) for M hyopneumoniae.  相似文献   

8.
An antibody-capture enzyme-linked immunosorbent assay (ELISA) for detection of antibody to turkey coronavirus (TCV) utilizing infectious bronchitis virus (IBV) antigen was developed. Anti-TCV hyperimmune turkey serum and normal turkey serum were used as positive or negative control serum for optimization of the ELISA system. Goat anti-turkey immunoglobulin G (light plus heavy chains) conjugated with horseradish peroxidase was used as detector antibody. The performance of the ELISA system was evaluated with 45 normal turkey sera and 325 turkey sera from the field and the cutoff point was determined. Serum samples of turkeys experimentally infected with TCV collected sequentially from 1 to 63 days postinfection were applied to the established antibody-capture ELISA using IBV antigens. The optimum conditions for differentiation between anti-TCV hyperimmune serum and normal turkey serum were serum dilution at 1:40 and conjugate dilution at 1:1600. Of the 325 sera from the field, 175 were positive for TCV by immunofluorescent antibody (IFA) assay. The sensitivity and specificity of the ELISA relative to IFA test were 93.1% and 96.7%, respectively, based on the results of serum samples from the field turkey flocks using the optimum cutoff point of 0.18 as determined by the logistic regression method. The ELISA values of all 45 normal turkey sera were completely separated from that of IFA-positive sera. The ELISA results of serum samples collected from turkeys experimentally infected with TCV were comparable to that of the IFA assay. Reactivity of anti-rotavirus, anti-reovirus, anti-adenovirus, or anti-enterovirus antibodies with the IBV antigens coated in the commercially available ELISA plates coated with IBV antigens could be utilized for detection of antibodies to TCV in antibody-capture ELISA.  相似文献   

9.
An enzyme-linked immunosorbent assay (ELISA) was developed for detection of antibody against porcine parvovirus in swine sera. The antigen used for the assay was partially-purified virus treated with fluorocarbon and shown to contain 7 proteins by sodium dodecylsulfate-polyacrylamide gel electrophoresis. Of these proteins 83-, 64- and 60-K proteins reacted in Western immunoblotting with swine serum after infection with porcine parvovirus. Antibody responses were demonstrated by ELISA in pigs subcutaneously-infected with porcine parvovirus as by hemagglutination-inhibition (HI) test and Western immunoblotting reaction with the 83-, 64- and 60-K viral proteins. The results of ELISA on random swine-serum samples were well-correlated with those of the HI test. These findings indicate the usefulness of the ELISA as a serological tool for porcine parvovirus infection.  相似文献   

10.
A double antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for measuring Aujeszky's disease virus (ADV) antigen concentration and an inhibition technique based on the former was developed for detection of antibodies to ADV. The results were checked by determining the cytopathic and serum neutralization titres. The correlation was satisfactory in both cases, with correlation coefficients above 0.8. When measuring ADV antigen concentration, the lower limit of detection was 10(3) TCID 50/0.2 ml. The sensitivity of ELISA in detecting antibodies to ADV was found to be superior to that of the serum neutralization test and, thus, enabled the testing of rabbit and guinea-pig sera.  相似文献   

11.
An indirect micro enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to Aujeszky's disease virus in pigs is described. A control antigen prepared from infected cells was included for each serum tested. Of 243 sera from serologically positive farms, 175 (72 per cent) and 147 (60 per cent) were positive by the ELISA test and microtitre serum neutralisation test, respectively. Failure to include a control antigen for each serum would have resulted in 14 sera (6 per cent) being differently recorded. Results for sera from experimental and field infections indicated that seroconversion was more quickly detected by the ELISA test than the microtitre serum neutralisation test. In addition to greater sensitivity the ELISA test has other advantages over the serum neutralisation test. ELISA is a rapid, cheap test which is not dependent on a continuous supply of cell cultures and which can be readily automated.  相似文献   

12.
A reliable bovine viral diarrhea (BVD) viral antigen was prepared from BVD virus grown on Madin Darby bovine kidney (MDBK) cells by solubilizing the virus with detergent MEGA-10 (decanoyl-N-methylglucamide) followed by removal of hydrophobic proteins with Triton X-100 treatment. By these treatments, problems of high background associated with BVD viral antigen in the enzyme-linked immunosorbent assay (ELISA) were eliminated. With this new antigen, an ELISA was adapted to detect bovine serum antibody against BVD virus. The diagnostic specificity of the assay in 403 bovine sera collected from a BVD virus-free herd was 100%; in 296 bovine sera with serum neutralizing antibody titers of greater than or equal to 1:2, 289 sera were ELISA positive (relative sensitivity of 97.6%), two sera gave false negative reactions (0.7%) and five sera gave suspicious reactions (1.7%). These interpretations were based on positive/negative (P/N) ratio readings, i.e. a P/N ratio of less than 1.50, 1.50-1.99 and greater than or equal to 2.00 were interpreted as negative, suspicious and positive reactions, respectively. The ELISA results gave excellent agreement with serum neutralization in detecting both seropositive and seronegative animals (Kappa = 0.994). The ELISA assay was considered to be technically superior to the serum neutralization test for the routine detection of BVD viral antibody in bovine sera.  相似文献   

13.
Pooled serum from specific pathogen-free (SPF) lambs vaccinated with sodium salicylate extracted (SSE) antigens of Pasteurella haemolytica serotype A1 was shown to contain antibody to other A serotype SSE antigens when tested by the enzyme-linked immunosorbent assay (ELISA). Specific antibody to serotype A1 SSE antigens was demonstrated by absorption of the serum pool with heterologous serotype SSE antigens.The type-specific antigens of serotypes A1 and A9 were prepared by phenol—water extraction (PWE) of their respective SSE antigens. The PWE antigens were examined in a sandwich ELISA where rabbit IgG anti-P. haemolytica A1 cells or A9 cells was used as a coating layer to bind PWE antigens. The specificity of these antigens was demonstrated by marked reduction of reactivity between serum from SPF lambs vaccinated with SSE of serotypes A1 or A9.  相似文献   

14.
An enzyme-linked immunosorbent assay (ELISA) was evaluated and compared in parallel with the standard complement fixation test (CFT) for the diagnosis of bovine subclinical paratuberculosis. Bovine sera preabsorbed with the mixture of Mycobacterium phlei and kaolin suspension were assayed for antibody activities to the crude protoplasmic antigen of Mycobacterium paratuberculosis in the ELISA. ELISA antibody titer was expressed as ELISA antibody index (EAI) value: EAI = (At-An)/(Ap-An), where At, Ap and An are the absorbance values of a 1:200 dilution of unknown test sera, a 1:400 dilution of positive control serum, and a 1:200 dilution of negative control serum. An EAI of 0.6 or greater was established as a reasonable cutoff point for a positive antibody titer by ELISA. Of the 156 sera from cattle with subclinical M. paratuberculosis-infection, 106 (67.9%) were positive by ELISA and 41 (26.3%) by CFT. Of the 3,880 sera from cattle in the herds which had no history or evidence of paratuberculosis, 3,875 (99.9%) were negative by ELISA, and 3,787 (97.6%) by CFT. Positive ELISA titers were detectable 1 to 5 months earlier than positive CFT titers in experimentally infected cattle, and 7 to 10 months earlier in naturally infected cattle. These results indicate that the ELISA should replace the CFT as the routine test of choice for the diagnosis of bovine paratuberculosis.  相似文献   

15.
An enzyme-linked immunosorbent assay (ELISA) for detecting serum antibodies to the porcine epidemic diarrhea coronavirus (PEDV) was established by using cell culture-grown PEDV as antigen for coating. Ultracentrifugation through 20 and 45% (w/w) sucrose cushions proved to be the best antigen purification method. Examination of 1024 swine sera showed a high specificity and a greater sensitivity of the ELISA, when compared with indirect immunofluorescence. Reference sera with high antibody titers to PEDV originated from two pigs experimentally infected with PEDV. Three different antigen purification methods and the advantages of the ELISA compared with an immunofluorescence test are discussed.  相似文献   

16.
Methods of preparation of Mycoplasma hyopneumoniae antigens for the enzyme-linked immunosorbent assay to detect specific antibody, and properties of the antigens, are described. The reactivity and specificity of antigen prepared by Sephacryl S-300 column chromatography after treatment of M. hyopneumoniae cells with Tween 20 (S-300 antigen) were superior to those of antigen prepared by Sephadex G-25 column chromatography after treatment with Tween 20, or to lipid antigen. There were no differences among strains MI-3, J and VPP11 of M. hyopneumoniae. The S-300 antigen did not show cross-reactivity against porcine hyperimmune sera produced by M. hyorhinis, M. hyosynoviae, M. hyopharyngis, M. flocculare and Acholeplasma granularum. Antibody was first detected in sera of pigs inoculated intranasally with M. hyopneumoniae at two to four weeks after inoculation and seven to eight weeks after pigs were contact-exposed to the same mycoplasma.  相似文献   

17.
Calves (7) were exposed to antigens of Micropolyspora faeni by the aerosol route for 9 weeks. The humoral immune response of calves to M faeni antigens was studied; immunoglobulins (Ig) E, G1, G2, A, and M were measured weekly in serum and nasal secretions by enzyme-linked immunosorbent assay (ELISA). Intradermal injection of antigen was performed during the 6th and 9th weeks; responses were evaluated at 30 minutes, 6 to 8 hours, 24, and 48 hours after injection. Total IgE levels in serum and nasal secretions, evaluated weekly, did not show any elevation. Micropolyspora faeni-specific IgE, IgA, IgG1, and IgG2, but not IgM, were produced by calves exposed to the antigen by the aerosol route; individual variability in magnitude of the response was marked. Thirty-minute skin tests were positive for cytotropic antibody in 2 of 3 aerosol-exposed calves by the 9th week, but delayed-type reactivity was not present. The ELISA test results were compared with those from sera of saline solution aerosol-exposed calves and from a parenterally immunized calf. Comparison of isotype-specific ELISA results obtained from M faeni aerosol-exposed calves with ELISA results from calves exposed to aerosolized ovalbumin according to a similar procedure indicated inherent problems in evaluating immune responses to environmental antigens. Aerosolized M faeni elicited a substantial antibody response. In particular, it is noteworthy that antigen-specific IgE responses were detected.  相似文献   

18.
Fowl adenoviruses free of avian adenovirus-associated virus, representing 10 serotypes, were tested for cross-reactivity in an enzyme-linked immunosorbent assay (ELISA). All antigens and antisera prepared in chickens, along with uninfected control antigen and normal chicken serum, were reacted in a checkerboard pattern with ELISA. There was considerable cross-reactivity among all serotypes tested. Homologous reactions were generally, but not always, stronger than heterologous reactions. ELISA was about as sensitive as virus neutralization in detecting antibodies. The high sensitivity plus broad-spectrum reactivity should make ELISA a preferred test for the detection of adenovirus antibodies in poultry flocks.  相似文献   

19.
Nine thousand commercial breeder chicks (Chankee) reared in a floor pen were exposed to restricted numbers of Eimeria tenella and E. necatrix oocysts to confer immunity. Antibody induction in these chicks was examined by the enzyme-linked immunosorbent assay (ELISA) with antigen prepared from E. tenella oocysts. The oocyst excretion pattern demonstrated recycled infections which continued in these chicks for greater than or equal to 22 days after exposure. Antibody levels in their sera, as determined by the mean absorbence values in ELISA, increased gradually up to 38 days post-inoculation. Mean absorbence values of sera from control chicks remained at a low level. When infected and control chicks were challenged with the two species of coccidia, the test chicks were protected against both species. The antibody level did not change for 8 days in the challenge groups, while in the control chicks, absorbence in ELISA rose significantly and the mean absorbence value was higher than that in immunized chicks. Some factors which influence the results of ELISA are considered and the applicability of this method to measuring immunity against coccidiosis in chickens is discussed.  相似文献   

20.
Chen YC  Chen CH  Wang CH 《Avian diseases》2008,52(1):124-129
Many commercial enzyme-linked immunosorbent assays (ELISAs) are unable to differentiate antibody responses to different avian influenza virus (AIV) subtypes. Developing an ELISA for specifically detecting the H5 antibody is the purpose of this study. Four monoclonal antibodies (Mabs) were raised using A/duck/Yunlin/04 (H5N2). They were confirmed as being specific to H5. Two of these antibodies showed hemagglutination inhibition (HI) activity using the HI test. Using immunodot blot assays, three Mabs recognized both Eurasian and American H5, whereas the other Mab recognized only the tested Eurasian H5 virus. When testing denatured H5 antigen, one of the Mabs lost its antigen binding activity using Western blotting. For detecting the H5 humoral response in serum, one monoclonal antibody was purified and labeled with horseradish peroxidase to set up a blocking ELISA. Chicken sera that blocked H5 Mab binding by > 29% were considered H5 antibody positive. Inhibition percentages for sera from chickens infected with other AIV subtypes, H1 to H15, were < 29%. This blocking ELISA was used for 478 field chicken serum samples. The results showed that the sensitivity and specificity of this ELISA were 98.3% (232/236) and 95.9% (232/242), respectively. This blocking ELISA could be used specifically for detecting the H5 humoral responses in chickens.  相似文献   

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