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Primary structure of prion protein may modify scrapie isolate properties
G A Carlson1, D Westaway, S J DeArmond
1McLaughlin Research Institute, Great Falls, MT 59401.
Summary
Scrapie incubation times vary based on prion protein (PrPSc) structure, not host selection. Differences in PrPSc amino acid sequence influence disease progression in mice.
Area of Science:
- Neuroscience
- Infectious Diseases
- Biochemistry
Background:
- Scrapie is a prion-induced neurodegenerative disease.
- Prions lack detectable nucleic acid.
- The prion protein scrapie isoform (PrPSc) is the sole known prion component.
Purpose of the Study:
- To investigate the influence of PrPSc primary structure on scrapie incubation times.
- To determine if scrapie isolate variations are epigenetic or due to host selection.
Main Methods:
- Inoculating inbred mouse strains (differing in Prn-p gene) with various scrapie isolates.
- Analyzing incubation periods and PrPSc molecular differences.
- Utilizing F1 and F2 hybrid mice for genetic analysis.
Main Results:
- Allogeneic PrPSc inocula increased scrapie incubation length and variability.
- PrPSc primary structure, not host selection, dictates incubation time.
- Prion incubation time gene (Prn-i) dominance observed in F1 hybrids.
Conclusions:
- Scrapie incubation time variations are epigenetic, driven by host-directed amino acid changes in PrPSc.
- PrPSc primary structure is the key determinant of scrapie pathogenesis.
- The findings challenge the nucleic acid genome hypothesis for prion diseases.