FINE MAPPING OF A SURFACE-ACCESSIBLE, IMMUNODOMINANT SITE ON THE BLUETONGUE VIRUS MAJOR CORE PROTEIN VP7

The 349-amino-acid major core protein VP7 of bluetongue virus (BTV) is both the most abundant viral structural protein and the major immunog enic serogroup-reactive viral antigen. Previous studies indicated that a conformation-dependant antigenic site, defined by the VP7-specific monoclonal antibody 20E9/B7/G2(20E9), was accessible from the virus su rface and that the binding of the monoclonal antibody to this epitope could be blocked specifically by antisera raised against different ser otypes of bluetongue virus, suggesting it is a serogroup-specific immu nodominant epitope. Using a combination of three different mapping str ategies, we have located the 20E9 binding site at the N-terminus of th e molecule, between amino acids 30 and 48. The fine mapping of the 20E 9 immunodominant epitope will facilitate structure-function analyses o f the major core protein and provide new opportunities to improve exis ting BTV serodiagnosis methods based on this immunogenic site. (C) 199 4 Academic Press, Inc.