EN
The aim of the experiments conducted was to modify the indirect ELISA to determine different immunoglobulin classes in the reaction of antibodies with bovine leukaemia virus. Rabbit sera immunized against bovine IgG₁, IgG₂ and IgM as well as serum conjugates were used in the modified method. Examinations of 100 reference serum samples from BLV-infected animals and 50 samples from BLV-free animals allowed us to establish the optimum dilution of the components used and the threshold optical densities of the test.