CP and viral infectious disease: In order to check whether the trans‐proteolytic cleavage processing of CPp25 is carried out by the virus protease and not by a plant protease, which could be induced by viral infection, we co‐infiltrated the M‐CS mutant, which does not replicate or produce any CP proteins because of two amino acid mutations at the cleavage site that release RdRP from the polyprotein, with either CPp25WT or CPp25M‐CS.