Studies on antigenic relatedness of classic and variant strains of infectious bursal disease viruses

Antigenic relatedness of six classic and variant strains of serotype 1 infectious bursal disease virus (IBDV) and one serotype 2 IBDV was investigated by Western blotting and enzyme-linked immunosorbent assay (ELISA) using polyclonal, monoclonal, and monospecific antibodies to single viral proteins (VP2 and VP3). All virus strains cross-reacted similarly, and the viruses were not distinguishable from each other by ELISA or Western blot analysis performed with polyclonal or non-neutralizing monoclonal and monospecific antibodies. Non-neutralizing antibodies against the VP2 (40 kilodaltons) reacted strongly with VP2 of classic and variant strains of serotype 1 and reacted weakly with VP2 of serotype 2 OH strain. This indicated that common antigens were recognized and that these epitopes were not strictly dependent on the native structure of the virus.