VIEW ARTICLE

Physiology and Biochemistry

Temperature-Reversible Aggregation of Two Strains 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 E. M. McGauley(3). (2)(3)Technicians, respectively, Research Station, Agriculture Canada, 6660 N.W. Marine Drive, Vancouver, B.C., Canada, V6T 1X2. Phytopathology 74:161-165. Accepted for publication 27 July 1983. Copyright 1984 Department of Agriculture, Government of Canada. DOI: 10.1094/Phyto-74-161.

Two strains of carnation ringspot virus, CRSV-R and CRSV-N, aggregate and disaggregate in a temperature-reversible manner at pH 5.0. Aggregated virions sedimenting at 300- 1,300 S and 10⁵ S were observed in a CRSV-R preparation (9.5 mg/ml) in the analytical ultracentrifuge at 31- 40 C, but were absent after cooling to 18 C. Electron microscopy of CRSV-R preparations (0.1 mg/ml) heated to 70 C showed small structured aggregates and large unstructured aggregates. Solutions of each virus strain, at various concentrations, were heated at a constant rate of 0.25 C/min while the absorbance at 340 nm was recorded. The temperature of aggregation was inversely proportional to the logarithm of virus concentration. The maximum absorbance attained by both strains on heating was proportional to the logarithm of virus concentration. Maximum rate of absorbance increase at each concentration was proportional to the logarithm of virus concentration. At high concentrations (4 mg/ml), the N strain required higher temperature for aggregation than the R strain but at lower concentrations (0.2 mg/ml) the R strain required higher temperatures than the N strain. In addition to this novel difference between the two strains, the serological properties and amino acid compositions of the strains were similar, but not identical.