Abstract
Treatment of purified preparations of tobacco rattle virus with 2 mM-EDTA decreased their infectivity, and that of RNA extracted from them, by about 90%. The effect of EDTA was apparently to remove divalent metal ions from the virus particles, making the RNA inside accessible to attack by a ribonuclease present in the preparations. Provided the enzyme activity was inhibited while the ions were absent, they could be put back with full restoration of full stability of infectivity.