Properties of Virus and RNA Components of Raspberry Ringspot Virus

Abstract

SUMMARY Particles of raspberry ringspot virus were homogeneous in immunoelectrophoresis tests but sedimented as three components, T, M and B, with sedimentation coefficients of 52, 92 and 130s respectively, and containing 0, 30 and about 44% RNA. The three components were serologically indistinguishable. In CsCl gradients, M and B were each homogeneous, with buoyant densities of 1.43 and 1.52 g./cm.3 respectively. Infectivity was associated with B. RNA extracted from the virus preparations was single-stranded and showed about 20% hyperchromicity in 0.1 m-sodium phosphate buffer at pH 7.0, indicating about 40% base-pairing. Analysis of RNA preparations by polyacrylamide gel electrophoresis revealed two predominant RNA species with mol. wt of 2.4 × 106 (RNA-1) or 1.4 × 106 (RNA-2); RNA-2 was indistinguishable in mol. wt from the RNA-2 of tobacco ringspot virus but RNA-1 migrated slightly more slowly than the RNA-1 of tobacco ringspot virus. M particles of raspberry ringspot virus contain one molecule of RNA-2; B particles contain either one molecule of RNA-1 or, probably, two molecules of RNA-2. Whereas B particles of raspberry ringspot virus were apparently homogeneous in CsCl gradients, B particles of tobacco ringspot virus formed two buoyant density classes.