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Etiology

Aggregation Properties of Carnation Ringspot Virus. J. H. Tremaine, Research Scientist, Research Station, Agriculture Canada, 6660 N.W. Marine Drive, Vancouver, B.C., Canada V6T 1X2; W. P. Ronald(2), and A. Valcic(3). (2)(3)Technicians, respectively, Research Station, Agriculture Canada, 6660 N.W. Marine Drive, Vancouver, B.C., Canada V6T 1X2. Phytopathology 66:34-39. Accepted for publication 14 July 1975. DOI: 10.1094/Phyto-66-34.

Three strains of carnation ringspot virus (CRSV) were obtained from single local lesions on plants infected with a culture of the virus. When virus particles of one strain (CRSV-A) were concentrated by dissolving high-speed centrifugation pellets in a small volume of 0.1 M sodium acetate buffer, pH 5, clusters of 12 virus particles arranged in an icosahedral symmetry were formed. Aggregation into linked clusters containing 23, 34, 45, or 56 virus particles also occurred. The sedimentation coefficients obtained for the virus monomer and the four classes of polymers were 135 S, 640 S, 932 S, 1175 S, and 1266 S, respectively; these values showed good agreement with theoretical sedimentation calculations. These aggregates were stable in the presence of 0.5 M 2-mercaptoethanol, 0.1 M urea, 0.1 M MgCl₂, or 0.1% sodium dodecyl sulfate, and during storage for 6 months at 4 C. However a portion of the aggregates dissociated into monomer at pH 7. A second strain (CRSV-R) formed another kind of aggregate, a two-dimensional net, in which reversible formation and dissociation occurred at 25 C and 4 C, respectively. A third strain (CRSV-N) aggregated in a similar temperature-dependent manner, but required higher virus concentrations or higher temperatures. The three strains were serologically related, but CRSV-A formed reactions of partial identity in gel diffusion tests with CRSV-R and CRSV-N.