Uses of biosensors in the study of viral antigens.

The introduction in 1990 of a new biosensor technology based on surface plasmon resonance has greatly simplified the measurement of binding interactions in biology. This new technology known as biomolecular interaction analysis makes it possible to visualize the binding process as a function of time by following the increase in refractive index that occurs when one of the interacting partners binds to its ligand immobilized on the surface of a sensor chip. None of the reactants needs to be labelled, which avoids the artefactual changes in binding properties that often result when the molecules are labelled.

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).

Mapping of viral conformational epitopes using biosensor measurements.

Earlier electron microscopy studies of the location of various antigenic 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 particle. In contrast, epitopes expressed in both intact particles and dissociated subunits (so-called metatopes) were found only at the one extremity of the particle containing the 5' end of the RNA. In the present study, the binding properties of antibodies to neotopes and metatopes were studied with the BIAcore.

A single amino acid substitution at N-terminal region of coat protein of turnip mosaic virus alters antigenicity and aphid transmissibility.

The antigenic activity of the N-terminal region of coat protein of turnip mosaic virus (TuMV) aphid transmissible strain 1 and non-transmissible strain 31 was examined by using a panel of monoclonal antibodies (MAbs) raised against the two virus strains as well as antisera raised against several synthetic peptides from the N-terminal region of the protein. The reactivity of these antibodies was tested in ELISA and in a biosensor system (BIAcore Pharmacia) using virus particles, dissociated coat protein and synthetic peptides as antigens. Substitution of a single amino acid at position 8 in the coat protein of TuMV strain 1 abolished any cross-reactivity between MAbs to strain 1 and the substituted peptide (strain 31) in ELISA although some cross-reactivity was apparent in BIAcore inhibition experiments.

Inhibition of in vitro cotranslational disassembly of tobacco mosaic virus by monoclonal antibodies to the viral coat protein.

It has been shown by others that translation of tobacco mosaic virus (TMV) RNA may begin before uncoating of particles is complete. We provide evidence that this cotranslational disassembly can be inhibited by incubating TMV treated at pH 8 with certain monoclonal antibodies (MAbs) specific for TMV coat protein. The most efficient inhibition was achieved by incubation with some anti-metatope MAbs known to bind to the TMV extremity that becomes disassembled first and contains the 5' end of the RNA, as well as with some anti-cryptotope MAbs that bind only to dissociated coat protein subunits.