In the present study, a total of 24 Mabs were produced against bluetongue virus (BTV) by polyethyleneglycol (PEG) mediated fusion method using sensitized lymphocytes and myeloma cells. All these clones were characterized for their reactivity to whole virus and recombinant BTV-VP7 protein, titres, isotypes and their reactivity with 24 BTV-serotype specific sera in cELISA. Out of 24 clones, a majority of them (n = 18)belong to various IgG subclasses and the remaining (n = 6) to the IgM class. A panel of eight clones reactive to both whole BTV and purified rVP7 protein were identified based on their reactivity in iELISA. For competitive ELISA, the clone designated as 4A10 showed better inhibition to hyperimmune serum of BTV serotype 23. However, this clone showed a variable percent of inhibition ranging from 16.6% with BTV 12 serotype to 78.9% with BTV16 serotype using 24 serotype specific sera of BTV originating from guinea pig at their lowest dilutions. From the available panel of clones, only 4A 10 was found to have a possible diagnostic application.

A monoclonal antibody (MAb) specific for the bluetongue virus (BTV) group specific antigen (VP7) was characterized for its reactivity with purified virus and recombinant BTV VP7 (rVP7) protein and its suitability for use in the sandwich ELISA. The MAb, designated as 5B5 was specific to VP7 and belongs to IgG2a subclass and was selected for the development of the sELISA in this study. The MAb had a titer of 1:25 with BTV and 1:2 with the rVP7 protein. The sELISA is based on capturing of BTV antigen with VP7 specific MAb followed by detection using BTV polyclonal antiserum raised in rabbits. The assay was evaluated with six cell culture adapted serotypes of BTV that have been isolated from India, 1, 2, 15, 17, 18 and 23. The assay could detect BTV antigen as early as day 8 in blood. It was also successfully applied for the detection of BTV group specific antigen in clinical samples of blood, washed RBCs, buffy coat and plasma. A total of 102 field samples from animals, suspected of being infected with BTV, were tested and 29.42% were positive. The blood samples were also amplified in cell culture which improved the sensitivity of the assay. Results confirmed that the sELISA is rapid and specific.