Accessibility of three continuous epitopes in tomato bushy stunt virus

Three peptides corresponding to residues 28-40, 138-154 and 380-387 of the coat protein of tomato bushy stunt virus (TBSV) were synthesized by the solid phase method and used to raise specific antibodies. These antibodies were used to follow the conformational changes that occur when TBSV particles swell under slightly alkaline conditions. Peptides 28-40 and 380-387 were found to correspond to continuous epitopes in the dissociated viral protein as well as in both compact and swollen virions. The region 138-154, which is also a continuous epitope of the monomeric protein, became accessible to antibody binding in the virion only when the particles were in the swollen state.