Kinetic and functional mapping of viral epitopes using biosensor technology.

Some monoclonal antibodies (Mabs) that react with the extremity of the tobacco mosaic virus (TMV) particle containing the 5' end of the RNA are able to block the disassembly of TMV by ribosomes while others are totally devoid of such activity. No correlation could be established between the binding kinetics and affinity of the Mabs and their inhibitory capacity. An epitope map of the Mab binding sites was constructed on the basis of kinetic two-site binding assays with the viral monomeric protein (TMVP) performed using biosensor technology (BlAcore). Mabs possessing inhibitory activity were found to bind to the part of the TMVP surface closest to the central axis in the polymerized particle. As this part of the subunit is known to interact with the viral RNA, it seems that inhibitory Mabs act by sterically preventing the interaction between virus and ribosomes. This study illustrates the advantages of the biosensor technology for locating conformational epitopes in viral proteins.