Enzyme-linked immunosorbent assay for the diagnosis of bovine leukosis: comparison with the agar gel immunodiffusion test approved by the Canadian Food Inspection Agency

Four commercially available bovine leukemia virus (BLV)-ELISA kits from Eur ope or the United States were compared to the agar gel immunodiffusion (AGI D) test officially approved by the Canadian Food Inspection Agency (CFIA). A total of 1200 cattle serum samples were used. Three ELISA kits based on t he envelope glycoprotein (gp51) gave an excellent correlation with the ACID test. The kappa values were 0.998, 0.984, and 0.986 for the ELISA kits #1, #2, and #3, respectively. The ELISA kit based on the p24 core protein was found to be less sensitive than the officially approved ACID test and detec ted 5.13% of false negatives. Forty BLV ACID strongly positive serum sample s were diluted. Based on the dilution experiment, the gp51 ELISA kits were found to be more sensitive than the ACID test kits. They were capable of de tecting antibodies in samples diluted up to 1/5000 (kit #1), 1/20 800 (kit #2) and 1/4000 (kit #3), whereas the ACID kit was only capable of detecting antibodies in samples diluted up to 1/100. Based on these observations, th e gp51 BLV-ELISA was recognized as an official test method for the serodiag nosis of bovine leukosis in Canada.