SVIBOR - Project code: 3-03-358

MINISTRY OF SCIENCE AND TECHNOLOGY

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Project code: 3-03-358


Improvements in the diagnosis and control of bovine leukosis


Main researcher: LOJKIĆ, MIRKO (26240)


Assistants
Type of research: applied
Duration from: 01/01/91. to 12/15/95.
Papers on project (total): 9
Institution name: Veterinarski institut, Zagreb (48)
Department/Institute: Department of virology
Address: Savska cesta 143
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 535-011
Fax: 385 (0)1 537-140
E-mail: mavi.veinst.hr
Summary: Program for the control and eradication of bovine enzootic leukosis (BEL) is based on the detection of infected bovines by means of serologica tests and culling of positive animals from further breeding before the manifestation of clinical signs. Consequently, the methods for serological identification of infected animals should be reliable, specific and sensitive to enable an early detection of infected animals even with a minimum antibody level. In Croatia, 51170 serum samples taken from bovines wewr assessed during the last three years (1991-1993), notably 24739 in 1991, 15389 in 1992 and 11042 in 1993. Enzyme immunoassay - gp 51 ELISA was used for the determination of antibodies to BLV in the blood serum and milk specimens collected from cows and compared with the results of immunodiffusion test (GDP). The results of our investigations showed that owing to used ELISA test there was a lower incidence of "new" cases. ELISA test showed to be 10-15% more sensitive compared to GDP test. With the use of ELISA test it was possible to detect the antibodies in milk, which is additional advantage over GDP test which can detect only the antibodies in the blood serum. Thus the examination of animals is simpler, as the withrawal of blood is avoided and this procedure usually causes a stress situation for an animal and also makes possible the iatrogenic spreading of infection. On the basis of obtained results it may be concluded that the serological ELISA test is simpler and cheaper method for the diagnosis of infected bovines. The contribution of these investigations is the use of a new program for the diagnosis of BEL by which it is possible to meet the international requirements and terms, in particular those in force in the EU, for an unobstructed turnover and trade of animals.

Keywords: ELISA immunoenzyme test, immunodifusion test, enzootic bovine leukosis virus

Research goals: Bovine enzootic leukosis (BEL) is a contagious disease caused by a virus of the family Retroviridae, genus HTLV-BLV. The disease is often characterised by lymphocytosis of B lymphocytes. In Croatia, about 15000 animals on big cattle-breeding farms are examined every year. Until 1989, GDP test alone was used and in 1990, the ELISA methodology was introduced for testing of both blood and milk samples. The disease was diagnostified on all farms and on an average 7% of animals were infected infected with BLV. The percentage of infected animals was reduced to 3% in the next five years, because of the culling of positive animals from further breeding. Immunodiffusion test, however, did not reveal all infected animals as repeated tests detected "new" positive animals also in the farms which have been proclaimed as BLV-free. The incidence of similar cases has been markedly reduced since the introduction of ELISA in 1989. The results of our investigations showed that ELISA test was by 15% more sensitive compared to GDP test. The aim of this investigation was to compare the results of serological blood analysis with GDP test and with new ELISA test and to assess the correlation between test results obtained in the blood and milk samples collected from the same animals. In addition, we wanted to investigate the relationship between the results in a pooled milk sample (taken from up to 50 cows), because this biotechnical method would make the diagnosis 50 times cheaper and would also enable more rapid identification of infected animals. Finally, the basic aim was to assess the reability, sensitivity ans specificity of such assessment in both individual and pooled samples in order to detect infected herds and individual animals.

OTHER ACHIEVEMENTS


  1. Name: Primjena nove metode dijagnostike (ELISA-test)
    Type of achievement: Technology
    Authors: M. Lojkić
Other information about the project.
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