Alleged reaction in gel-immunodiffusion of an IgM monoclonal antibody with alfalfa mosaic virus and cucumber mosaic virus is an artefact

A previously reported spurious serological cross-reaction between alfalfa mosaic virus (AMV) and cu-cumber mosaic virus (CMV), which had been defined by the reaction in gel-immunodiffusion tests of a single IgM monoclonal antibody (MAb), MAb 8, was no longer detected in the presence of 0.1 M-NaC1. The non-specific reactivity of this IgM was also confirmed in Western blotting assays. When skimmed milk was used as a blocking agent and as a diluent of antibodies, MAb 8 failed to recognize AMV and CMV coat proteins. Hence, it is concluded that the alleged cross-reaction between AMV and CMV is due to non-specific binding of MAb 8 and that there is no evidence for a serological relationship between these two viruses. While generating hybridomas to alfalfa mosaic viru