Related Experiment Videos
Biological activity of subfractions from scrapie-associated fibrils
1Department of Veterinary Public Health, School of Veterinary Medicine, Obihiro University of Agriculture, Japan.
Abstract:
Subfractions, a nucleic acid fraction and a PrP fraction consisting of PrP17-25, a core fragment of PrPsc, were prepared from the scrapie-associated fibril-enriched fraction from scapie-affected mouse brains. The nucleic acid fraction consisted mainly of variously fragmented DNA and no scrapie-specific nucleic acid was detected in the fraction by SDS polyacrylamide gel electrophoresis. To examine the biological activity, the nucleic acid fraction was either first introduced into mouse L-929 cells before or after nuclease treatments, then transfected cell lysates prepared 2 weeks later were inoculated into mice, or directly inoculated into mice with or without the PrP fraction. The PrP fraction alone was also inoculated into mice. Mice inoculated with the transfected cell lysates or with the nucleic acid fraction alone showed no scrapie signs during their lifespan or the observation period. While 60% of the mice inoculated with the PrP fraction alone and 67% of those inoculated with the fraction together with the nucleic acid fraction showed clinical signs of scrapie. A nucleic acid molecule bound covalently to PrP17-25 was not detected. The results obtained by the present procedures so far suggest scrapie infectivity to be associated with PrPsc, which does not contain any detectable scrapie-genome molecule as either free or covalently bound nucleic acid.
Insights
Scrapie infectivity is linked to the prion protein (PrPsc), not detectable nucleic acids. Experiments show PrPsc fractions, with or without nucleic acids, caused scrapie in mice, while nucleic acids alone did not.
Area of Science:
- Neuroscience
- Molecular Biology
- Infectious Diseases
Background:
- Scrapie is a prion disease affecting the central nervous system.
- The role of nucleic acids in prion infectivity remains debated.
- Prion protein scrapie (PrPsc) is a key component of infectious prions.
Purpose of the Study:
- To investigate the role of nucleic acids in scrapie infectivity.
- To determine if PrPsc alone or in combination with nucleic acids causes scrapie.
- To identify the infectious agent in scrapie-associated fibrils.
Main Methods:
- Preparation of nucleic acid and PrP fractions from scrapie-affected mouse brains.
- Inoculation of mice with nucleic acid fraction, PrP fraction, or both.
- Nuclease treatments and cell transfection experiments.
- Monitoring mice for clinical signs of scrapie.
Main Results:
- Mice inoculated with PrP fraction alone or with nucleic acid fraction showed clinical signs of scrapie.
- Mice inoculated with nucleic acid fraction alone did not develop scrapie.
- No scrapie-specific nucleic acid was detected, nor was a nucleic acid molecule covalently bound to PrP17-25.
Conclusions:
- Scrapie infectivity is associated with PrPsc.
- Detectable scrapie-genome molecules are not essential for infectivity.
- The infectious agent does not appear to be a nucleic acid-based genome.