Purification and partial characterisation of beet mild yellowing virus and its serological detection in plants and aphids

Beet mild yellowing virus (BMW) was reversibly precipitated at temperatures below about 5°C and this property was used as a final step in a purification procedure which yielded about 1 mg virus/kg tissue. Purified virus was infective and had an A200/A280 ratio of about 1–8. BMW particles were isometric with a diameter of 26 nm, sedimented at 116 S, had a buoyant density in caesium chloride of 1.42 g/cm³ and a coat protein mol. wt of 25 400. An antiserum to BMW had a titre in immunodiffusion tests of 1/256 and was used in immunodiffusion tests, immunospecific electron microscopy (ISEM) and enzyme-linked immunosorbent assay to demonstrate a close serological relationship between BMW and beet western yellows virus. BMW was readily detected by ISEM in plants and also in aphid vectors after treatment of aphid extracts with a chloroform:butanol mixture.