Sedimentation properties of the scrapie agent

Area of Science:

• Neuroscience
• Virology
• Biochemistry

Background:

• Scrapie is a fatal neurodegenerative disease affecting sheep and goats.
• The infectious agent of scrapie, known as the scrapie agent, is not well characterized.
• Understanding the physical properties of the scrapie agent is crucial for developing diagnostic and therapeutic strategies.

Purpose of the Study:

• To determine the sedimentation behavior of the scrapie agent in mouse spleen homogenates.
• To investigate the effect of sonication and detergent treatment on the scrapie agent's sedimentation.
• To compare the sedimentation profile of the scrapie agent with known subcellular markers.

Main Methods:

• Ultracentrifugation of spleen homogenates from scrapie-infected mice using a fixed-angle rotor.
• Analysis of sedimentation profiles at a specific omega2t value (3 X 10(10) rad2/sec).
• Comparative analysis with sedimentation profiles of free polyribosomes and other subcellular markers.

Main Results:

• Approximately 90% of the scrapie agent sedimented under the tested conditions.
• Sonication and sodium deoxycholate treatment did not significantly alter the agent's sedimentation.
• The scrapie agent's sedimentation profile resembled free polyribosomes but differed from other cellular components.

Conclusions:

• The scrapie agent behaves as a discrete infectious particle.
• The agent is likely separable from cellular membranes.
• Further purification and characterization of the scrapie agent are feasible.