Inactivation of the scrapie agent by pronase.

Scrapie agent derived from infected mouse brain was partially purified by agarose-polyacrylamide gel electrophoresis. The preparation was subjected to treatment with RNase A, DNase I, pronase, sodium dodecyl sulfate and sodium dodecyl sulfate-pronase combination. Almost total inactivation of scrapie infectivity resulted when the partially purified scrapie agent was treated with sodium dodecyl sulfate-pronase combination whereas the treatment with sodium dodecyl sulfate or pronase alone reduced the infectivity by about 98%. No significant reduction of scrapie infectivity was observed with either RNase A or DNase I treatments. These results confirm that the transmission of scrapie cannot be achieved in the absence of a protein component.