PARTIAL ANTIGENIC CHARACTERIZATION OF POTATO-VIRUS-S (ANDEAN STRAIN) BY MONOCLONAL-ANTIBODIES

Four mouse monoclonal antibodies (MoAbs) against potato virus S Andean strain (PVSA) were tested. While MoAbs 2 and 3 reacted only with comp lete virions and were apparently specific for epitopes dependent on qu aternary structure, MoAbs 1 and 4 appared to be conformation independe nt and reacted with exposed regions on native virions as well as on th e surface of dissociated coat protein subunits. This seems to be an ev idence of metatope existence. The results of competitive binding tests together with reaction patterns of individual MoAbs suggest that the used MoAbs reacted with at least two different epitopes on PVSA partic les or polypeptide subunits. Immunoblot analysis of proteolytically cl eaved PVSA capsid protein (CP) confirmed close proximity of epitopes r ecognized by MoAbs 1 and 4. Anti-PVS polyclonal antibody recognized bo th intact CP and its natural or artificial digest, while the MoAbs bou nd to intact CP only. These results indicate that the surface virus-sp ecific epitopes are located near the terminus of CP molecule as it is characteristic for potyviruses.