POTATO LEAFROLL VIRUS CONTAINS A DOUBLE-STRANDED DNA

The nucleic acid of potato leafroll virus (PLRV) was isolated from highly purified virus preparations by 2 methods. From a treatment with 0.5 N perchloric acid at 70.degree. C and quantitative estimation of the products, the DNA:protein ratio was found to be nearly 40:60 (wt/wt). The nucleic acid extracted under more protective conditions, namely, with a mixture of phenol and sodium dodecyl sulfate, is resistant to RNase, sensitive to DNase, possesses a sharp melting profile with a Tm [melting temperature] of 87.4.degree. C in 1 .times. SSC, a buoyant density of 1.698 in cesium chloride solution and a molecular weight of 0.56 .times. 106. The buoyant density and Tm values are slightly higher than those of DNA preparations from the uninfected host plant, Physalis floridana Rydb. The nucleic acid of PLRV is a double-stranded DNA.