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BRUCELLA MELITENSIS : IMPROVEMENT OF BRUCELLOSIS PREVENTION IN SHEEP AND GOATS

Objective

The objective is to improve diagnosis of Brucellosis in sheep and goats by the development and the evaluation of tests detecting the greatest number of infected animals.
The objective of the project was to improve diagnosis of Brucellosis in sheep and goats caused by B melitensis by thedevelopment and the evaluation of tests detecting the greatest number of infected animals. Initial work was focussed on the development of a sensitive assay to survey infection in lactating animals with a modified milk ring test and a milk enzyme linked immunosorbent assay (ELISA). The first results obtained indicated that the milk ring test performed on milk of sheep and goats was not working as well as for bovines, and this test was not suitable for monitoring brucellosis in sheep and goats. Preliminary results showed that an indirect ELISA seems promising for the testing of goat and sheep milk. It has been difficult to compare the indirect ELISA for serum diagnosis of 3 laboratories because of the different parameters of the protocol and the 3 methods of calculation of the cutoff for positive or negative reaction. Finally, it was decided to produce negative and positive standard sera for both sheep and goats with common dilutions and calculation of units by using the 4 parameter logistic curve with software available for both IBM compatible and Apple Macintosh computers. Preliminary results showed that the performance of the competitive ELISA was comparable to that of the indirect ELISA. Analysis of antibody immune response by immunoblotting showed that B melitensis infected and vaccinated sheep have antibodies against outer membrane proteins and S-lypopolysaccharide and cytoplasmic proteins, but all animals do not always respond to the same antigens.
The improvement of brucellosis prevention will reduce the cost of the eradication of the disease for EEC, increase the benefits of agriculture, allow free circulation of animals within the EEC, decrease the risks of human contamination. Classical serologic tests or skin test alone do not detect all infected animals and should therefore be combined. ELISA is more sensitive than classical serologic tests. Whether all infected animals reacting to a skin test are detected by ELISA is not known. Regarding to the survey of infection in lactating cattle, ELISA is much more sensitive than the milk ring test. Such assay should be developed and evaluated in sheep and goats.

Work will be focussed on :

a) the development of a sensitive assay to survey infection in lactating animals with a modified milk ring test and a milk ELISA;
b) the development and the evaluation of the delayed type hypersensitivity test (intradermal test);
c) the development and the evaluation of sensitive ELISA procedures for serum diagnosis;
d) the analysis of antibody response on sera of experimentally infected animals, to identify the better diagnostic antigens.

Coordinator

Institut National de la Recherche Agronomique (INRA)
Address
Tours
37380 Nouzilly
France

Participants (4)

Centraal Diergeneeskundig Instituut
Netherlands
Address
Edelhertweg 15
8219PH Lelystad
Centre National d'Études Vétérinaires et Alimentaires (CNEVA)
France
Address
22 Rue Pierre Curie
94703 Maisons Alfort
FACULTES UNIVERSITAIRES NOTRE-DAME DE LA PAIX
Belgium
Address
Rue De Bruxelles 61
5000 Namur
MAFF Central Veterinary Laboratory
United Kingdom
Address
Woodham Lane New Haw Addlestone
KT15 3NB Weybridge