Detection of antibodies against porcine parvovirus in swine sera by enzyme-linked immunosorbent assay

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.     

Detection of antibodies against reticuloendotheliosis viruses by an enzyme-linked immunosorbent assay

A microplate indirect enzyme-linked immunosorbent assay (ELISA) for antibodies against reticuloendotheliosis virus (REV) was consistently more sensitive than indirect immunofluorescent-antibody tests. Limits of antibody detection were comparable to those obtained in virus neutralizations. Detection of REV-infected chickens long after infection and after immunofluorescent antibody has waned makes ELISA especially suitable for screening chicken flocks.     

An enzyme-linked immunosorbent assay for enzootic bovine leukosis virus antibodies

An enzyme-linked immunosorbent assay (ELISA) for detecting antibodies to enzootic bovine leukosis (EBL) virus is described and its sensitivity compared with that of the agar gel immunodiffusion test (AGIDT) using 198 sera collected in Great Britain. There was 95 per cent agreement between the ELISA and AGIDT, when sera with positive/negative ratio (P/N) values of 1 . 5 or greater were considered positive. A total of 259 out of 264 sera (98 per cent) collected in Northern Ireland had P/N values of less than 1 . 5, the remaining sera having P/N values of 1 . 5 and 1 . 6. As Northern Ireland is clinically and serologically free of EBL infection it is proposed that sera with P/N values of 1 . 5 and 1 . 6, which account for approximately 3.5 per cent of the total sera tested, are considered doubtful and should be tested by another serological test.     

An enzyme-linked immunosorbent assay for detection of antibodies against bovine pestivirus

A competitive enzyme-linked immunosorbent assay was developed and compared with the serum neutralisation test for bovine pestivirus using 508 cattle sera and serial serum samples from a goat hyperimmunized with five bovine pestivirus isolates. There was 96.7% agreement between the two tests. The relative sensitivity of the enzyme-linked immunosorbent assay compared to the serum neutralisation test was 95.2% and the relative specificity was 99.4%. The titres of individual animals in the assay did not show a close correlation with serum neutralisation test titres. This may be because the antibodies measured in the two tests are directed against different viral proteins. The enzyme-linked immunosorbent assay has the advantage of being quicker and cheaper than the serum neutralisation test. The configuration used in the ELISA means sera from all species can be tested for pestivirus antibody using the same set of reagents.     

Blocking enzyme-linked immunosorbent assay for detection of antibodies against bovine enterovirus

A blocking enzyme-linked immunosorbent assay (ELISA) was developed for detecting antibodies against bovine enterovirus (BEV) in bovine sera. In this ELISA, bovine serum samples were allowed to react with captured viral antigens (by specific chicken IgG), before the addition of specific mouse IgG for measuring non-occupied viral epitopes. The ELISA was slightly more sensitive and required a shorter time period than traditional serum neutralisation (SN). Among the 871 bovine serum samples tested so far, the titres produced by this assay had a significant correlation with those recorded by SN. The ELISA could be used as an alternative assay for SN in a large-scale BEV antibody investigation.     

Detection of IgM antibodies against canine distemper virus in dog and mink sera employing enzyme-linked immunosorbent assay (ELISA)

An enzyme-linked immunosorbent assay (ELISA) for the detection of IgM antibodies against canine distemper virus (CDV) in canine and mink serum is described. The diagnostic potential of this technique was evaluated by analyzing sera from natural or experimental infections in dog and mink and negative control sera. These results were compared with results obtained in the developed CDV IgG ELISA and in the virus neutralization test. The IgM test, which requires only a single serum specimen, is a useful method for diagnosing current or recent CDV infections in dog and mink.     

Detection of antibodies to mouse thymic virus by enzyme-linked immunosorbent assay.

Enzyme-linked immunosorbent assay was used to detect serum antibodies to mouse thymic virus, a herpesvirus that causes thymic lesions and immunosuppression. Antibodies were detected in mice that had received single or multiple injections of the virus and were also found in mice housed in contact with the experimentally infected animals. By contrast, mice not exposed to mouse thymic virus or those inoculated with an uninfected thymus preparation remained seronegative. A serological survey of eight mouse colonies revealed one positive colony, confirmed by virus isolation. These results show that the test is sufficiently sensitive and specific to be used for routine screening of mice.     

Detection and quantification of antibodies to infectious bronchitis virus by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) for detecting and quantifying antibodies to infectious bronchitis virus (IBV) is described. Purified antigen, prepared on sucrose density gradients, was required to decrease the nonspecific background, and saline was found to be superior to bicarbonate buffer for coating the cuvettes with antigen. The sensitivity of the test in measuring antiserum titers could be altered greatly and linearly by adjusting the protein content of the antigen. The ELISA was able to detect an antibody response to IBV infection earlier than the virus-neutralization (VN) test. Antibody titers obtained by ELISA were considerably higher than those obtained by VN. Serotypes of IBV could not be differentiated with ELISA because of extensive antiserum cross-reactivity. The utility of ELISA in studies on IBV is discussed.     

Detection of serum antibodies against Ehrlichia risticii in Potomac horse fever by enzyme-linked immunosorbent assay

An indirect enzyme-linked immunosorbent assay (ELISA) was developed which was specific and sensitive in detecting antibodies to Ehrlichia risticii in Potomac horse fever (PHF). The ELISA antibody titers were correlated with the indirect fluorescent antibody (IFA) titers. E. risticii propagated in human histiocyte culture was purified on renografin gradient and the band of the organisms at a density of 1.182 g/ml was used as antigen. ELISA antibody titers were determined through computer assisted analysis, the observed antibody titers were derived by serial serum dilutions and using a resultant standard curve the predicted antibody titers were obtained from a single serum dilution. The standard curve had a correlation coefficient of 0.8975. The observed and predicted antibody titers were in good agreement, as the respective titers fell within a two-fold range. There was a good correlation between ELISA and IFA test results, but the ELISA titers were several times higher. In experimental infections of horses produced with the infected equine whole blood and the Ehrlichia infected macrophage culture, the antibodies were first detected in two weeks and one week postinoculation (PI), respectively. In both cases the titers reached a peak in about 4 weeks PI with a mean titer of 1:16558 and 1:4030, respectively. The antibody titers of the convalescent sera of field cases of PHF were comparatively lower than the experimentally infected horses.     

Enzyme-linked immunosorbent assay for the detection of antibodies to bovine viral diarrhea virus in bovine sera

A specific and sensitive enzyme-linked immunosorbent assay (ELISA) was established for the detection of antibodies to bovine viral diarrhea virus (BVDV) in bovine sera. Polyethylene-glycol concentrated, equilibrium density gradient purified BVDV was used as test antigen at an optimal amount of 1 microgram/well, whereas the optimal concentration of conjugate was at 1/2000 dilution. The standardized test encountered no non-specific reaction with test sera at a starting dilution of 1/10. A total of 50 bovine serum samples was assayed for the presence of antibodies against BVDV by ELISA and serum neutralization test (SNT). A positive correlation between the 2 tests was found. However, ELISA could be as much as 500-fold more sensitive than SNT in detecting low levels of BVDV antibodies.     

An enzyme-linked immunosorbent assay for the detection of bovine antibodies to vesicular stomatitis virus

An indirect enzyme-linked immunosorbent assay (ELISA) was developed to detect bovine antibody to vesicular stomatitis virus (VSV). Serum samples from cows experimentally infected with the New Jersey serotype of VSV (VSV-NJ) were assayed by the ELISA and serum-neutralization (SN) assay. The ELISA was as sensitive as the SN assay in detecting bovine antibody to VSV. The correlation between SN titers and ELISA values at absorbance at 405 nm was statistically significant. The ELISA was not specific for VSV-NJ, however, and could detect serum samples positive to the Indiana serotype of VSV that had SN titers of greater than or equal to 480. Nonspecific reactions were due to cross-reactive group-specific viral proteins that are shared by both serotypes. The cross-reactivity allows the use of a single rapid test in identifying both serotypes of VSV from the other exotic vesicular diseases, especially foot-and-mouth disease. The ELISA titers of serum samples positive for VSV-NJ were comparable with the corresponding SN titers of each sample. The sensitivity, rapidity, and ease of the ELISA system and the use of a single test in identifying both serotypes of VSV from the other exotic vesicular diseases make this ELISA suitable as a rapid diagnostic assay for VS.     

Detection of equine antiplatelet and antineutrophil antibodies by enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (elisa) was standardised and applied for the detection of anti-platelet and antineutrophil antibodies using a heterologous system consisting of equine platelets or neutrophils and antisera raised in rabbits. The standardised technique consisted of using Immulon type 3 plate, I per cent gelatine as a blocking solution, poly-L-lysine buffer as a coating solution, unfixed antigen, 90 μl test serum, horseradish peroxidase conjugated antibody and o-phenylenediamine dihydrochloride as a substrate. The number of unfixed platelets or neutrophils required for optimum detection of antibodies was 250,000 per well. Unfixed cellular antigens were as good as their extracts and superior to paraformaldehyde-fixed antigens in detecting specific antibodies. Microtitre plates coated with platelet or neutrophil antigens could be stored at 4° and −70°C for four to five weeks without significant loss of antigenicity. The ELISA was very sensitive in that antiplatelet antibody was detected up to a titre of 1:204,800 and antineutrophil antibody to a titre of 1:51,200. Some cross-reactivity (1:1600) was detected in antiplatelet and antineutrophil sera for neutrophil and platelet antigens, respectively. Platelet-associated antibody was also detected in extracts from platelets pretreated with 1:2 and 1:8 dilutions of antiplatelet serum. Standardised elisa detected antiplatelet antibodies in nine and antineutrophil antibodies in three of 100 isologous equine blood typing sera.     

Evaluation of an enzyme-linked immunosorbent assay for detection of antibodies to bovine virus diarrhoea virus in milk

The present study shows that milk is an appropriate source for detection of seroreactors to bovine virus diarrhoea virus (BVDV). There was close agreement between antibody titres in serum and in skim milk, as determined by an indirect enzyme-linked immunosorbent assay. The antibody titres were usually lower in skim milk than in serum, but all seropositive cows (n = 84) were also skim milk-positive and all but one seronegative cow (n = 55) proved negative in skim milk. During lactation, the level of antibodies to BVDV in milk showed an inverse relationship to the amount of milk produced. However, there was a sufficient level of antibodies in milk throughout lactation to permit an adequate determination of BVDV antibody status in dairy cows. There was a mutual good agreement between milk antibody titre in the four mammary quarters, irrespective of milk cell count. Milk can be used to detect seroreactors to BVDV. Milk is preferable to blood in large-scale epidemiological studies, since the sampling procedure is much simpler.     

Evaluation of enzyme-linked immunosorbent assay for quantitation by subclass for bovine antibodies.

The enzyme-linked immunosorbent assay (ELISA) was evaluated for use in the quantitative measurement of bovine immunoglobulin IgG1 and IgG2 antibodies. A method for standardization was devised in which IgG1 or IgG2 was directly adsorbed to polystyrene tubes and the actual degree of binding was calculated by using different input amounts of 125I-labeled IgG1 or IgG2. Values for quantity of IgG1 antibodies to human serum albumin were only slightly higher when measured by the ELISA than when measured by quantitative precipitation although the value measured by the ELISA for IgG2 antibodies was twice that determined by quantitative precipitation. This discrepancy could result from conjugate cross reactivity, differences in affinity between antibodies of the 2 subclasses, or the occurrence of IgG2 nonprecipitating antibodies. The danger of overlooking subclass anti-globulin cross reactivity because of the failure to detect it by immunoprecipitation, also is illustrated. In addition, only enzyme-antibody conjugates prepared with specifically purified antibodies were effective, and reproducibility of individual data points required that 4 replicate determinations be performed. Advantages, pitfalls, and limitations of the ELISA are discussed.     

Detection of antibody to Mycoplasma F38 in goat sera by an enzyme-linked immunosorbent assay

Summary An indirect enzyme-linked immunosorbent assay (ELISA) was developed to screen goat sera at a single dilution for antibody to mycoplasma F38. Antibody was detected in sera of six convalescent goats following experimental infection. Antibody was also detected in 34 sera three to four weeks after vaccination. No antibody was detected in 164 sera from goats without a history of vaccination or infection with contagious caprine pleuropneumonia. The ELISA was more sensitive than the complement fixation test in detecting antibody in vaccinated goats.

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Deteccion De Anticuerpos Contra Micoplasma F38 En Suero Caprino Mediante La Prueba Elisa

Resumen Se utilizó la prueba ELISA para detectar anticuerpos contra micoplasma F38. Se detectaron anticuerpos en el suero de seis cabras convalecientes, después de la infección experimental. Los anticuerpos también se detectaron en 34 sueros, tres a cuatro semanas después de la vacunación. Ciento sesenta y cuatro sueros de cabras sin historia de vacunación e infección con pleuroneumonía caprina, se encontraron libres de anticuerpos. La prueba enzimática ELISA fue más sensitiva que la prueba de fijación de complemento para detectar anticuerpos en cabras vacunadas.

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Detection De l'Anticorps Dirige Vers Le Mycoplasma F38 Dans Des Serums De Chevre Par Un Test Immuno-Enzymatique

Résumé Un test immuno-enzymatique indirect (ELISA) a été développé pour trier à une seule dilution les sérums de chèvre vis-à-vis de l'anticorps anti-mycoplasma F38. L'anticorps a été détecté dans les sérums de six chèvres convalescentes après infection expérimentale. L'anticorps a également été détecté dans 34 sérums trois à quatre semaines après vaccination. Les sérums de 164 chèvres sans commémoratifs de vaccination ou d'infection par la pleuropneumonie contagieuse caprine ne possédaient pas d'anticorps. L'ELISA est plus sensible que le test de fixation du complément pour détecter l'anticorps chez les chèvres vaccinées.

     

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bovine viral diarrhoea virus (BVDV) in cattle sera

A microtitre ELISA has been established for the quantitation of antibodies to bovine viral diarrhoea virus (BVDV). Single dilutions of sera were assayed and units of antibody were calculated from a standard curve. In order to detect the maximum number of responding animals both IgG1 and IgG2 antibody should be assayed, although detection of IgG1 alone was nearly as effective. The ELISA was as sensitive as the virus neutralization test for detection of antibody; comparison of an ELISA that detected IgG1 plus IgG2 antibody to BVDV with the virus neutralization test gave a correlation coefficient (r) of 0.89 (P less than 0.001 for 95 compared sera). Although similar amounts of IgG1 and IgG2 antibodies were present in sera from both experimentally- and naturally-infected cattle, antibody to BVDV in colostrum and in the sera from young calves was predominantly IgG1. The number of adult cows with antibody was 40 out of 41 while 36 of 44 calves reared in a beef unit were found to have produced antibody by the time they were 31.5 weeks old, an indication of the high prevalence of BVDV in the cattle population.