Purification of the group-specific antigen of bluetongue virus by chromatofocusing

A method for the purification of the precipitating antigen of bluetongue virus (BTV) is described. The results obtained indicate that the precipitating antigen is identical with a core protein of BTV having a molecular weight of 39,000 (P7). So far all bluetongue virus serotypes have been shown to possess this protein. It is evident therefore that a group-specific reaction could be based on the presence of antibodies against this core protein. The purification of this protein by chromatofocusing proved relatively easy to perform and immunodiffusion tests revealed a group-specific reaction.