Infection of cattle with Yersinia enterocolitica O:9 a cause of the false positive serological reactions in bovine brucellosis diagnostic tests.

in Veterinary Microbiology (1996), 48(1-2), 101-12

During the last four years, an increasing number of cattle herds were classified positive by brucellosis screening tests in areas of Belgium and France free of the disease. No clinical symptom of ... [more ▼]

During the last four years, an increasing number of cattle herds were classified positive by brucellosis screening tests in areas of Belgium and France free of the disease. No clinical symptom of brucellosis was reported in these animals and no Brucella abortus strains were isolated. After two years, no brucellosis outbreak was registered in all of the herds concerned. On this basis, all the serological reactions observed were classified as false positive. An ELISA using Yersinia Outer membrane Proteins (YOPs) as antigens was developed in order to discriminate between a Yersinia enterocolitica O:9 infection and a Brucella abortus infection. Antibodies against YOPs were detected in sera from Y. enterocolitica O:9 experimentally infected cattle (n = 4) but not in sera from B. abortus experimentally infected cattle (n = 4). In a field study, 66.7% of the 174 serum samples from cattle presenting false positive serological reactions showed anti-YOPs antibodies whereas only 10% of 454 sera, classified negative by the brucellosis screening tests, showed anti-YOPs antibodies. Our results suggest that infections with Y. enterocolitica O:9 may cause false positive reactions in brucellosis testing. [less ▲]

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 ▲]

Serological and cutaneous testing of bovine tuberculosis with the A60 antigen complex from Mycobacterium bovis, strain Calmette-Guérin

in Preventive Veterinary Medicine (1995), 23

A60, a major thermostable macromolecular antigen complex of Mycobacterium bovis strain Calmette-Guerin (BCG), is immunodominant in tuberculosis and able to elicit both humoral and cellular immune ... [more ▼]

A60, a major thermostable macromolecular antigen complex of Mycobacterium bovis strain Calmette-Guerin (BCG), is immunodominant in tuberculosis and able to elicit both humoral and cellular immune reactions in infected hosts. A60-based ELISA and cutaneous tests have been used, in conjunction with the PPD-based skin reaction, in a control group of healthy animals, and in a herd including tuberculous animals. Cutaneous testing with A60 yielded results comparable with those with PPD: both were negative with control cattle and positive with infected animals. Moreover, comparative cutaneous testing with avian tuberculin yielded similar results with PPD and A60. When animals from the infected herd were tested with both avian and bovine sensitins, 54% of cattle were diagnosed as fully positive, 26% suspect, and 20% negative. Serological analysis with the A60-ELISA of part of the infected herd yielded 74% positive, 21% suspect and 5% negative results. Thus, positivity was 74% for serological analysis and 54% for cutaneous testing, whereas positive plus suspect results were 95% for serological analysis and 80% for cutaneous testing. It can be concluded that A60 can be used in place of PPD for cutaneous testing in cattle, and that the diagnostic value of the A60-ELISA is superior to that of the PPD-cutaneous test. [less ▲]

Brucellose enzootique à Brucella suis biotype 2 chez le sanglier (sus scrofa) en Belgique

in Annales de Médecine Vétérinaire (1994), 138

Evaluation de l'activité protectrice de la fraction de la paroi de Brucella insoluble dans le SDS et identification d'antigènes de Brucella utilisables pour le diagnostic

in John Libbey Eurotext (Ed.) AUPELF-UREF (1994)

Identification et clonage des antigènes de diagnostic de la brucellose: perspectives d'application

in Prevention of brucellosis in the mediterranean countries. Proceedings of the international seminar (1992)

Brucellose bovine : le test d'agglutination en présence du facteur rhumatoïde après traitement du sérum par le dithiothréitol, dans la différenciation des animaux vaccinés et infectés

in Annales de Médecine Vétérinaire (1992), 136

La recherche en Brucellose entreprise par le CEB (2e partie)

in Les élevages belges (1991)

La bronchite vermineuse chez les bovins

in Journal des UPA (1989)

Les entérotoxémies

in Probio-Revue (1989)