Evidence for the low molecular weight nature of scrapie agent

Abstract

THE nature of the aetiological agent of scrapie disease, a transmissible encephalopathy naturally affecting sheep and goats, remains a perplexing problem of fundamental biological importance. Recent studies on brain tissue from outbred Syrian hamsters infected with a strain originating from the Chandler strain of mouse-adapted scrapie have led to a report of a DNA component essential for scrapie infectivity as suggested by sensitivity to DNase¹. The data presented here describe a purification procedure resulting in scrapie infectivity which migrates during polyacrylamide gel electrophoresis as a defined area of infectivity in a region characteristic of low molecular weight nucleic acid. This electrophoretically migrating species of the scrapie agent retains the characteristic disease properties by intercerebral inoculation of crude hamster brain homogenates. Infectivity isolated from this region was resistant to treatment with a combination of SDS and proteinase K followed by ethanol precipitation. These data support the suggestion that the scrapie agent may be an infectious low molecular weight DNA.