MAPPING OF VIRAL CONFORMATIONAL EPITOPES USING BIOSENSOR MEASUREMENTS

Earlier electron microscopy studies of the location of various antigen ic sites in tobacco mosaic virus indicated that epitopes specific for the quaternary structure and absent in dissociated viral subunits (so- called neotopes) were present along the entire length of the virus par ticle. In contrast, epitopes expressed in both intact particles and di ssociated subunits (so-called metatopes) were found only at the one ex tremity of the particle containing the 5' end of the RNA. In the prese nt study, the binding properties of antibodies to neotopes and metatop es were studied with the BIAcore. From the results of capture assays w ith viral subunits and on the basis of binding stoichiometry calculati ons, it was possible to demonstrate the presence of neotope and metato pe specificities on additional parts of the viral surface where they h ad not been identified before by classical immunoassays. In two site b inding assays it was also found that a neotope specificity could be in duced in dissociated viral subunits by the binding of a first antimeta tope antibody. The results clearly demonstrated the superiority of the biosensor technology for mapping conformational epitopes in viral pro teins.