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Updated: Jun 24, 2026
Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep
Published on: January 19, 2014
Lesion profiling at primary isolation in RIII mice is insufficient in distinguishing BSE from classical scrapie
Katy E Beck1, Melanie Chaplin, Michael Stack
1Veterinary Laboratories Agency-Weybridge, New Haw, Addlestone, Surrey KT15 3NB, UK.
Abstract:
Primary isolation of bovine spongiform encephalopathy (BSE) in RIII mice generates a lesion profile believed to be reproducible and distinct from that produced by classical scrapie. This profile, which is characterized by peaks at gray matter areas 1, 4 and 7 (dorsal medulla, hypothalamus and septal nuclei), is used to diagnose BSE on primary isolation. The aim of this study was to investigate whether the BSE agent could be present in sheep diagnosed with classical scrapie, using lesion profiles in RIII mice as a discriminatory method. Sixty-two positive scrapie field cases were collected from individual farms between 1996 and 1999 and bioassayed in RIII mice. Fifty-five of these isolates transmitted successfully to at least one mouse. Of the 31 that produced adequate data to allow lesion profile analysis, 10 showed a consistent profile with peaks at brain areas 1, 4 and 7. All inocula for this subgroup were derived from sheep of genotype ARQ/ARQ. While the 1-4-7-scrapie profile exhibited similarities to BSE in RIII mice at primary isolation, it was distinguishable based on histopathology, immunohistochemistry and cluster analysis. We conclude that caution should be taken to distinguish this profile from BSE and that additional parameters should be considered to reach a final diagnosis.
Insights
This study investigated if bovine spongiform encephalopathy (BSE) is present in sheep with classical scrapie. Researchers used lesion profiles in RIII mice, finding a distinct profile that requires caution for diagnosis.
Area of Science:
- Veterinary Neurology
- Transmissible Spongiform Encephalopathies
- Comparative Pathology
Background:
- Bovine spongiform encephalopathy (BSE) diagnosis relies on distinct lesion profiles in RIII mice.
- Classical scrapie in sheep presents a different lesion profile.
- The potential presence of BSE in sheep scrapie cases requires investigation.
Purpose of the Study:
- To determine if the BSE agent is present in sheep diagnosed with classical scrapie.
- To utilize RIII mouse lesion profiles as a discriminatory diagnostic method.
- To differentiate BSE from ovine scrapie based on neuropathological findings.
Main Methods:
- Bioassay of 62 ovine scrapie field cases in RIII mice.
- Analysis of brain lesion profiles, focusing on gray matter areas 1, 4, and 7.
- Histopathology, immunohistochemistry, and cluster analysis for differentiation.
Main Results:
- Ten of 31 analyzed isolates from ARQ/ARQ genotype sheep showed a 1-4-7 lesion profile.
- This ovine "1-4-7-scrapie" profile shared similarities with BSE in RIII mice.
- Histopathology, immunohistochemistry, and cluster analysis distinguished the ovine profile from BSE.
Conclusions:
- A distinct lesion profile (1-4-7) was identified in some sheep scrapie cases.
- This profile, while similar to BSE, is distinguishable through detailed analysis.
- Caution is advised when diagnosing BSE, and additional parameters are necessary.
