Further studies of the infectivity and stability of extracts and homogenates derived from scrapie affected mouse brains

The activity of the scrapie agent is extremely sensitive to the action of 0·1M sodium periodate at pH 3·5, to 6M urea and to 90 per cent. aqueous phenol. After extraction with fluorocarbon the scrapie agent becomes much more sensitive to the action of heat, and somewhat more sensitive to the action of proteolytic enzymes. No scrapie activity was found in preparations of whole basic protein derived from cell homogenates and from heated scrapie brain. These preparations of basic protein had been purified chromatographically. Slightly higher titration values are obtained, when dilution assays are carried out using a 0·15 per cent. suspension of normal brain in place of physiological saline.