Abstract
Hydrangea ringspot virus has been purified to near homogeneity. Virus nucleic acid was identified as single-stranded RNA with an S value of 33·6 before and 21·1 after formaldehyde denaturation. Nucleic acid mol. wt. determinations made by linear log sucrose density gradient centrifugation gave values of 2·25 x 106 and 2·14 x 106, respectively, for native and formaldehyde-treated RNA. Electrophoresis on polyacrylamide gels before and after formaldehyde denaturation gave mol. wt. values of 2·64 x 106 and 2·03 x 106. The values from formaldehyde denatured RNAs are considered the most reliable. Thermal denaturation profiles showed a Tm of 55·2 °C in 0·1 M-sodium phosphate, pH 7·0, and a hyperchromicity of 22·4%.