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Inactivation of the scrapie agent by pronase
Abstract:
Scrapie agent derived from infected mouse brain was partially purified by agarose-polyacrylamide gel electrophoresis. The preparation was subjected to treatment with RNase A, DNase I, pronase, sodium dodecyl sulfate and sodium dodecyl sulfate-pronase combination. Almost total inactivation of scrapie infectivity resulted when the partially purified scrapie agent was treated with sodium dodecyl sulfate-pronase combination whereas the treatment with sodium dodecyl sulfate or pronase alone reduced the infectivity by about 98%. No significant reduction of scrapie infectivity was observed with either RNase A or DNase I treatments. These results confirm that the transmission of scrapie cannot be achieved in the absence of a protein component.
Insights
Scrapie infectivity is eliminated by treating the agent with both proteinase and sodium dodecyl sulfate. This confirms that a protein component is essential for scrapie transmission.
Area of Science:
- Neuroscience
- Biochemistry
- Infectious Diseases
Background:
- Scrapie is a fatal neurodegenerative disease affecting sheep and goats.
- The causative agent of scrapie is known as a prion, a misfolded protein.
- Understanding the prion's composition is crucial for developing diagnostics and therapeutics.
Purpose of the Study:
- To investigate the biochemical composition of the scrapie agent.
- To determine the role of protein and nucleic acid components in scrapie infectivity.
Main Methods:
- Partial purification of the scrapie agent from infected mouse brain using agarose-polyacrylamide gel electrophoresis.
- Treatment of the purified agent with RNase A, DNase I, pronase, sodium dodecyl sulfate (SDS), and a combination of SDS-pronase.
Main Results:
- Treatment with RNase A or DNase I did not significantly reduce scrapie infectivity.
- Treatment with pronase or SDS alone reduced infectivity by approximately 98%.
- Combined treatment with SDS and pronase almost completely inactivated scrapie infectivity.
Conclusions:
- The results strongly indicate that a protein component is essential for scrapie infectivity.
- Nucleic acids (RNA or DNA) are not required for scrapie transmission.
- These findings support the prion hypothesis, which posits that prions are infectious proteins.