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

Abstract

SUMMARY 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 A 200/ A 280 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/cm 3 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.