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Purified scrapie prions resist inactivation by procedures that hydrolyze, modify, or shear nucleic acids
Abstract:
Prions were purified from scrapie-infected hamster brains and incubated for 24 hr at 65 degrees with 2 mM Zn2+ or 5 mM Mg2+; no loss of infectivity was observed. Bacteriophage M13, tobacco mosaic virus (TMV), potato virus X, and potato spindle tuber viroid were all inactivated by divalent metal ions under these conditions. Prions also resisted inactivation by prolonged digestions with DNase I, RNases A and T1, and micrococcal nuclease. Prions were resistant to psoralen photoadduct formation using high concentrations of psoralens; in contrast, M13 bacteriophage was inactivated by low concentrations of all these psoralens. Hydroxylamine failed to inactivate prions even after lengthy exposures to concentrations as high as 1 M, while TMV and M13 were both inactivated. Sonication of prions failed to decrease infectivity even though rod-shaped aggregates were disrupted while both M13 and TMV lost infectivity.
Insights
Prions, infectious proteins, resist inactivation by various agents including metal ions, nucleases, and hydroxylamine. This study highlights the unique stability of prions compared to viruses and viroids.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- Prions are misfolded proteins responsible for transmissible spongiform encephalopathies.
- Understanding prion stability is crucial for developing decontamination and therapeutic strategies.
Purpose of the Study:
- To investigate the resistance of prions to various chemical and physical inactivation methods.
- To compare prion stability with that of other infectious agents like viruses and viroids.
Main Methods:
- Purification of prions from infected hamster brains.
- Incubation with divalent metal ions (Zn2+, Mg2+).
- Treatment with nucleases (DNase I, RNases A and T1, micrococcal nuclease).
- Exposure to psoralen photoadduct formation and hydroxylamine.
- Sonication treatment.
Main Results:
- Prions retained infectivity after incubation with Zn2+ or Mg2+, while M13 bacteriophage, TMV, PVX, and PSTVd were inactivated.
- Prions resisted inactivation by multiple nucleases.
- Prions were resistant to psoralen photoadduct formation and hydroxylamine, unlike M13 and TMV.
- Sonication disrupted prion aggregates but did not reduce infectivity, whereas M13 and TMV lost infectivity.
Conclusions:
- Prions exhibit remarkable resistance to a wide range of chemical and physical inactivation treatments.
- This inherent stability distinguishes prions from viruses and viroids, posing challenges for their elimination.
- The findings underscore the unique nature of prions and inform strategies for managing prion diseases.