Sedimentation characteristics of the scrapie agent from murine spleen and brain.

Sedimentation profiles of the scrapie agent in extracts of murine spleen and brain were determined by analytical differential centrifugation. Infectivity profiles of the agent from the two tissues were similar. Sedimentation of the agent was not substantially altered by detergent treatment with sodium deoxycholate. In the presence of detergent, centrifugation at an omega2t value of 3.0 x 1010 rad2/s in a fixed-angle rotor sedimented 90% of the agent. Comparative studies with radioisotopically labeled Simian virus 40 showed that centrifugation at an omega2t value of 1.6 x 10(10) rad2/s removed 90% of the virions. The sedimentation profile of the scrapie agent was similar to that observed for cellular ribosomal RNA. Heating infectious extracts of spleen to 80 degrees C for 30 min resulted in the destruction of 95% of the RNA while sedimentation of the scrapie agent was unchanged. These studies establish a limited range of particle sizes for the scrapie agent.