Properties of a Virus Inhibitor from Spinach Leaves and Mode of Action

Abstract

A procedure was shown for obtaining inhibitor of virus infection from the sap of spinach leaves. The leaf sap was brought to 50% saturation with solid ammonium sulfate. The precipitate was suspended in neutral phosphate buffer (PB) and filtrated through a Sephadex G-100 gel column. The active fractions were combined and further purified by DEAE cellulose and CM-Sephadex C-25 column chromatographies. The purified inhibitor lost its inhibitory activity by heating at 100C for 10min. The inhibitor inhibited TMV infection on bean and tobacco, while it showed no or a little effect on Chenopodium amaranticolor. When the inhibitor was treated on the undersurface of bean leaves and TMV was inoculated on the uppersurface, the weak inhibitory activity was observed. The inhibitor adsorbed on the leaf surfaces could not be easily removed by Triton X-100 treatment. The inhibitor also showed inhibitory activity to TMV-RNA infection on bean leaves. This reaction was not due to contamination of ribonuclease in the inhibitor preparation.