Mapping of two immunodominant antigenic epitopes conserved among the major inner capsid protein, VP7 of five bluetongue viruses.

A combination of polyclonal, monoclonal, and oligoclonal antibodies was used in Western blot to analyze intact VP7 proteins and their proteolytic peptide fragments of five bluetongue viruses found in the United States. Two linear immunodominant antigenic determinants were located and identified on this major inner capsid protein. One of the antigenic epitopes, which consisted of 11 residues (LTRAIARAAYV), was mapped by polyclonal antibody to the carboxyl terminus of the viral protein (residues 339 through 349). The second epitope (ARQPYGFFLETEEVYQPG) was located by both monoclonal and oligoclonal antibodies and mapped between residues 122 through 139. The exact locations of these two linear and continuous epitopes were also confirmed by competition with sequence-specific synthetic peptides. These epitopes were highly conserved among the VP7 proteins of all five U.S. bluetongue viruses.