Limitations of different ELISA procedures for localizing epitopes in viral coat protein subunits.

The reactivity of monoclonal antibodies (McAbs) to the coat protein of tobacco mosaic virus (TMVP) with the isolated coat protein, disks, virions and a number of antigenic variants of TMV was tested in eight different ELISA procedures. Although certain McAbs, when used as detecting antibody in the liquid phase, did not react with some of these antigens, they were able to bind to them when used as the capturing antibody on the solid phase. This finding was attributed to the ability of the trapping McAb to induce a complementary conformation in the antigen presented in the liquid phase. In many cases, the reactivity of the McAbs was found to depend on the format of the ELISA. This finding together with the presence of oligomers in viral coat protein preparations made it impossible to map TMVP epitopes on the surface of the viral subunit by means of competitive ELISA.