Evaluation of three serum i-ELISA's using monoclonal antibodies and protein G as peroxidase conjugate for the diagnosis of bovine brucellosis

in Veterinary Microbiology (2004), 100

Three i-ELISAs using LPS, the immunodominant component of Brucella abortus, were developed with three different conjugates: monoclonal antibodies 1C8 (anti-bovine IgG(1)) and 3H3 (mainly specific for ... [more ▼]

Three i-ELISAs using LPS, the immunodominant component of Brucella abortus, were developed with three different conjugates: monoclonal antibodies 1C8 (anti-bovine IgG(1)) and 3H3 (mainly specific for bovine IgG(2) but also reacting with IgG(1)) and protein G (reacts with both bovine IgG subclasses). Using a cut-off value of 2.5U/ml, the i-ELISA with 3H3 as conjugate had a specificity (95% CI: 98.32-99.63%) that was significantly higher than the same assay with 1C8 (95% CI: 96.08-98.26%) or PG (95% CI: 95.83-98.09%). In areas where false positive serological reactions (FPSR) were common, the specificity of the i-ELISAs decreased significantly. The specificity of the i-ELISAs increased with the age of the animals tested, irrespective of the conjugate. The specificity of the i-ELISAs and traditional tests was also examined using sera from animals infected per os with bacteria bearing LPS similar to the Brucella LPS. It appeared that Yersinia enterocolitica O:9, Xanthomonas maltophilia and Salmonella urbana infections induced FPSR both in the i-ELISAs and in the traditional tests, but the 3H3 assay was significantly less prone to produce false positive reactions than the 1C8 and PG assays. The i-ELISAs were more sensitive, allowed earlier detection, and were more persistent than the traditional serological tests both in experimentally and naturally Brucella-infected animals. Weekly i-ELISA monitoring of experimentally infected pregnant heifers (previously vaccinated or not) allowed a prediction of abortion. Furthermore, the 1C8 assay showed significantly higher titres irrespective of day post-infection and vaccination status. The accuracy of the assay could be improved by making use of additional information (e.g. animal age or conjugate) and by selecting appropriate cut-off points on the basis of the prevailing epidemiological situation. The i-ELISAs appear an appropriate choice in order to maintain an official brucellosis-free status because of their sensitivity, early detection and long persistence and, for the same reasons, seem especially valuable for the detection of latent carriers (i.e. animals classified negative by classical serological tests) among imported [less ▲]

Recommandations de l’association d’épidémiologie et de santé animale concernant la lutte contre la rhinotrachéite infectieuse bovine (IBR) en Belgique

in Annales de Médecine Vétérinaire (2001), 147

Panorama des démarches qualité : à chaque stratégie son outil.

in Quatrième Carrefour des Productions animales : Les démarches de qualité en production de viandes : Pourquoi ? Pour qui ? (1999, January 27)

Panorama des démarches qualité: à chaque stratégie son outil.

Poster (1999)

Latent Bovine Herpesvirus 1 Infection in Calves Protected by Colostral Immunity

in Veterinary Record : Journal of the British Veterinary Association (1995), 137(3), 70-1

Specific bovine brucellosis diagnosis based on in vitro antigen-specific gamma interferon production.

in Journal of Clinical Microbiology (1995), 33(3), 706-12

In order to improve the specificity of the diagnosis of bovine brucellosis, we developed a test which can be regarded as an in vitro correlate of the delayed-type hypersensitivity test (DTH). A mixture of ... [more ▼]

In order to improve the specificity of the diagnosis of bovine brucellosis, we developed a test which can be regarded as an in vitro correlate of the delayed-type hypersensitivity test (DTH). A mixture of cytoplasmic proteins from Brucella melitensis B115 was used as a specific antigenic stimulus in bovine whole blood culture. Supernatants harvested at 18 to 24 h after the in vitro antigenic stimulus were assayed for their gamma interferon (IFN-gamma) content by using a commercial sandwich enzyme-linked immunosorbent assay kit. The IFN-gamma assay was evaluated with 10 heifers during the course (80 days) of an experimental infection and with 14 cows from an ongoing brucellosis outbreak. All of these animals were slaughtered, and pertinent organs were subjected to classical bacteriological analyses. In addition, we analyzed 23 field cases in which false-positive serological reactions occurred. The IFN-gamma results were compared with those of the standard DTH and a battery of serological assays, and they were correlated with bacteriological data. Both for the experimental infection and for the field brucellosis outbreak, the IFN-gamma assay detected infection in more animals than any combination of the serological tests, and it detected infection earlier than these tests. Finally, none of the samples from cows showing false-positive serological reactions was classified as positive by the IFN-gamma assay, attesting to its specificity and to its usefulness in interpreting ambiguous serological results. A rapid and convenient alternative to the DTH, the IFN-gamma assay appears to be an ideal method that is complementary to the serological diagnosis protocols. [less ▲]

Caractérisation et typage de souches de Clostridium perfringens par la méthode ELISA

in Biotechnologies du diagnostic et de la prévention des maladies animales (1994)

Effect of Repeated Intradermal Injections of Bovine Herpesvirus Type 1 Antigen on Seronegative Cattle

in Veterinary Record : Journal of the British Veterinary Association (1992), 130(17), 372-5

Forty-three cattle seronegative to bovine herpesvirus-1 (BHV-1) were given from one to five intradermal injections of BHV-1 inactivated antigen at four-week intervals. This delayed hypersensitivity test ... [more ▼]

Forty-three cattle seronegative to bovine herpesvirus-1 (BHV-1) were given from one to five intradermal injections of BHV-1 inactivated antigen at four-week intervals. This delayed hypersensitivity test was assessed by the increase in skin thickness. The activity of the antigen was assessed in five animals which had a previous natural BHV-1 infection with clinical signs and seroconversion. Anti-BHV-1 antibodies were detected by seroneutralisation and an enzyme-linked immunoassay. Only one animal showed a significant but slight increase in skin thickness after the first test, but it was negative after a second test. The animals remained seronegative after the first test. Seroconversion was identified in 11 of the 43 animals (25 per cent) submitted to repeated delayed hypersensitivity tests. Five of 37 animals seroconverted after only two tests. The serological response was transient in seven of 11 seroconverted calves. Repeated hypersensitivity tests were therefore able to induce a serological response in seronegative calves but the response was weak and often transient. The test must therefore be applied cautiously to seronegative animals. [less ▲]