MONOCLONAL-ANTIBODY FOR THE DEMONSTRATION BY ELISA OF ANTIBODIES TO PROTEIN P24 OF ENZOOTIC BOVINE LEUKOSIS VIRUS IN INDIVIDUAL AND POOLED BLOOD-SERUM AND MILK SAMPLES

A sensitive and specific ELISA for the demonstration of antibodies to the protein p24 of enzootic bovine leukosis virus (EBVL) using a 'capt ure' monoclonal antibody to this protein (MAb p24) was developed. The method is sensitive enough to detect the international reference serum E4/10 in pooled blood serum samples collected from up to 50 cows, or, if a 10-fold concentrate of milk whey is tested, in samples of bulk m ilk collected from up to 400 cows. The application of MAb p24 has cons iderably increased not only the sensitivity, but also the specificity of ELISA. Moreover it is possible to differentiate reliably between po sitive and 'false positive' reagents by testing a suspicious sample in a pair of wells of which one is coated with MAb p24 alone and the oth er with dhe complex MAb p24+ EBLV antigen and the subsequent calculati on of 'specific absorbance'. This method, showing the highest sensitiv ity of detection of antibodies to EBLV p24 described so far, can becom e an effective tool on the sanitation of infected herds as well as in checks of the EEL-free status. A diagnostic kit suitable for commercia l manufacture has been devised.