The serological method relies on antigen-antibody reactions. The most common test of this type is the enzyme-linked immunosorbent assay (ELISA).

ELISA is a serological method that uses enzyme labelled antibodies, predominantly alkaline phosphatase. In its essence, the test relies on antibody adsorption to polystyrene plates. The adsorbed gamma-globulins quantitatively bind the virus from the plant extract, which in turn binds the gamma-globulins labelled with the enzyme. Such a complex, formed only when the virus corresponding to the antibodies used is present in the extract, is then detected by adding a specific enzyme developer. When the virus is present in the plant, the yellow color appears in individual wells.