Conformational specificity of monoclonal antibodies used in the diagnosis of tomato mosaic virus.

Ten monoclonal antibodies (McAbs) were raised to the tobamovirus, tomato mosaic virus (ToMV). Seven of the McAbs reacted with ToMV only when tested in an ELISA format, involving antibody-coated plates, which preserved the quaternary conformation of the viral protein. Two McAbs which reacted with ToMV only in an ELISA using virus-coated plates recognized an antigenic determinant present only on the disassembled form of the viral coat protein. One McAb reacted with both the assembled and dissociated forms of ToMV protein. All McAbs reacted in an identical manner with the 15 ToMV strains and isolates tested, confirming the previously established serological homogeneity of the ToMV species. Only two of the McAbs cross-reacted with two other tobamoviruses: tobacco mosaic virus (TMV) and ribgrass mosaic virus. Seven variations of ELISA were compared for their suitability to detect ToMV and TMV in tomato plants. Double antibody sandwich ELISA could be performed with a single McAb to ToMV as enough accessible epitopes are present on the virus to bind simultaneously to the coating and biotin-labelled antibody.