Purification and some particle properties of anthriscus yellows virus, a phloem-limited semi-persistent aphid-borne virus

Anthriscus yellows virus (AYV), a phloem-limited virus transmitted in the semi-persistent manner by the aphid Cavariella aegopodii, was purified by treatment of leaf extracts with cellulasc, followed by differential and sucrose density gradient centrifugation. ‘The preparations contained isometric particles c. 29 nm in diameter which were unstable unless stored in buffer at pH 8.0 containing 1 mM CaCl₂,. The particles sedimented as two components, ’full‘ nucleoprotein particles with A₂₆₀/A₂₈₀= 1.83 containing about 42% nucleic acid, and ’empty‘ protein shells with A₂₆₀,/A₂₈₀= 0.73; their buoyant densities in CsCl solutions were 1.52 and 1.27 g/cm³. Respectively. Yields of ihe nircleoprotein particles were c. 1.75 mg/kg leaf tissue. The particles contained a single species of RNA, of mol. wt 3.6 × 10 “(10 000 nucleotides). Particle protein preparations contained four electrophoretic species, of mol. wt (× 10³) 35.0, 28.3, 23.3 and 22.3.C. aegopodii did not transmit AYV from purified preparations. A rabbit injected with AYV preparations produced antibodies that coated AYV particles in electron microscope tests, but gave variable reactions in immunosorbent electron microscopy (ISEM), depending on the composition of the medium. No reactions were obtained in enzyme-linked inimunosorbent asjay (ELISA). No serological relationship was detected in ISEM between AYV and any of 10 viruses that resembled it in one or more properties.