Scrapie agent contains a hydrophobic protein

Area of Science:

• Neuroscience
• Biochemistry
• Infectious Diseases

Background:

• Scrapie is a degenerative nervous system disorder affecting sheep and goats.
• Previous research suggested a protein component is crucial for scrapie agent infectivity, but direct evidence was limited by purification challenges.

Purpose of the Study:

• To provide direct evidence for a protein moiety in the scrapie agent.
• To investigate the role of protein and hydrophobic domains in scrapie agent infectivity and properties.

Main Methods:

• Enrichment of the scrapie agent (100- to 1000-fold) to obtain highly purified preparations.
• Treatment of purified scrapie agent with proteinase K and diethylpyrocarbonate to assess infectivity.
• Chromatographic analysis using phenyl-Sepharose to investigate hydrophobic properties.

Main Results:

• Digestion with proteinase K destroyed over 99.9% of scrapie agent infectivity in purified preparations.
• Diethylpyrocarbonate also inactivated the scrapie agent, indicating a role for protein modification.
• Less purified preparations showed no significant reduction in infectivity after these treatments.
• The scrapie agent exhibited hydrophobic properties, binding to phenyl-Sepharose and requiring detergents for elution.

Conclusions:

• These findings provide strong evidence for a protein component essential for scrapie agent infectivity.
• The study suggests the presence of hydrophobic domains within the scrapie agent.
• Further research is needed to determine if the infectious protein is also responsible for the agent's hydrophobic characteristics.