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Sedimentation characteristics of the scrapie agent from murine spleen and brain
Abstract:
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.
Insights
This study characterized the scrapie agent
Area of Science:
- Neuroscience
- Virology
- Biochemistry
Background:
- Scrapie is a fatal neurodegenerative disease.
- The nature of the scrapie agent remains incompletely understood.
- Determining the physical properties of the scrapie agent is crucial for understanding its pathogenesis.
Purpose of the Study:
- To determine the sedimentation profile of the scrapie agent in murine spleen and brain extracts.
- To investigate the effect of detergent treatment on scrapie agent sedimentation.
- To establish the particle size range of the scrapie agent.
Main Methods:
- Analytical differential centrifugation of scrapie agent extracts.
- Treatment with sodium deoxycholate (a detergent).
- Comparative centrifugation with Simian virus 40 (SV40).
- Heat treatment to assess RNA stability.
Main Results:
- Scrapie agent infectivity profiles were similar in spleen and brain.
- Detergent treatment did not significantly alter scrapie agent sedimentation.
- Centrifugation at a specific omega2t value (3.0 x 10^10 rad^2/s) with detergent sedimented 90% of the agent.
- The sedimentation profile resembled cellular ribosomal RNA.
- Heating to 80°C for 30 minutes destroyed 95% of RNA without affecting scrapie agent sedimentation.
Conclusions:
- The scrapie agent exhibits a defined range of particle sizes.
- The agent's sedimentation is independent of RNA.
- These findings provide insights into the physical characteristics of the infectious agent.
