Artichoke Italian latent virus

Virus particles are isometric and ca 30 nm in diameter with an angular outline. After sucrose density gradient centrifugation, purified virus preparations separate into three classes of particles: empty protein shells without RNA (T) and two nucleoproteins (M and B), sedimenting at 55S, 96S and 121S, respectively. The M and B particles contain 24 and 41% single-stranded RNA, respectively, with positive polarity. The virus genome consists of two components with MW of 2,4000,000 (RNA1) and 1,500,000 (RNA2). In polyacrylamide gel electrophoresis, protein preparations from AILV particles migrate as a single band with a MW of 54,000 (Savino et al., 1977). RNA2 has been partially sequenced. It encodes a large precursor polyprotein containing the viral coat protein (F Grieco, Consiglio Nazionale delle Ricerche Centro di Studio sui Virus e le Virosi delle Colture Mediterranee, Universita di Bari, Italy, unpublished data; EMBL accession number X87254).