Monoclonal antibodies and bluetongue virus diagnosis.

A blocking enzyme linked immunosorbent assay (ELISA) is described for the detection of group specific antibodies to bluetongue virus (BTV). The test is based upon the interruption of the reaction between BTV antigen and a group specific monoclonal antibody raised against BTV by the addition of serial dilutions of either bovine or ovine test sera. The presence of group specific antibodies to BTV in the test serum, results in inhibition of the monoclonal antibody which is detected as a reduction in the expected optical density (OD) reading. The test is capable of the detection of antibodies to all 22 types of BTV but unlike the agar gel precipitin (AGP) test does not show cross-reactions with antibodies to epizootic haemorragic disease (EHD) viruses. Antibodies to cellular proteins which give rise to complications in the AGP test and indirect ELISA are not detected by this assay. Preliminary studies indicate that due to its high specificity and sensitivity, the blocking ELISA is an ideal alternative to the AGP test. The use of such a monoclonal antibody would also facilitate the standardization of diagnostic testing between laboratories.