The Structure of Infectious Pancreatic Necrosis Virus RNA

Abstract

Summary The RNA from infectious pancreatic necrosis virus has been purified and had a sedimentation velocity of 14S on sucrose gradients, a buoyant density of 1.60 g/ml in Cs2SO4 and pyrimidine to purine ratios near unity. The RNA had the appearance of a linear double stranded molecule with an average length of 0.92 µm and a standard deviation of 0.07 µm when observed under the electron microscope using the Kleinschmidt protein film technique. This would correspond to a mol. wt. of 2.4±0.2 × 106. The RNase A resistance of IPN virus RNA exhibited a marked salt dependence; it was 92% resistant in 0.1 m-NaCl, but only 9% resistant, or less, in 0.01 m-NaCl. The RNA was resistant to denaturation by boiling at NaCl concentrations of 0.04 m or higher, but did denature at lower concentrations. Polyacrylamide gel electrophoresis of the RNA indicated that two RNA species were present and the standard deviation of lengths in the electron microscope indicated that they could not differ by more than 4 × 105 in mol. wt.