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Naturally occurring scrapie in Southdown sheep
J W Tyler1, D M Weaver, J R Turk
1Department of Veterinary Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia 65211, USA. tylerj@missouri.edu
Journal of Veterinary Internal Medicine
|June 5, 1999
Summary
Naturally occurring scrapie in Southdown sheep was characterized. The study found QQ genotype sheep exhibited clinical signs and confirmed scrapie diagnosis through histopathology and prion protein analysis.
Area of Science:
- Veterinary Neurology
- Sheep Disease Research
- Prion Disease Studies
Background:
- Scrapie is a fatal, transmissible spongiform encephalopathy affecting sheep.
- Understanding scrapie in different breeds is crucial for disease management.
- Southdown sheep are a common breed with limited prior scrapie characterization.
Purpose of the Study:
- To characterize clinical and pathological findings of naturally occurring scrapie in Southdown ewes.
- To investigate the role of prion protein (PrP) gene polymorphism in scrapie susceptibility in this breed.
- To evaluate diagnostic markers in cerebrospinal fluid (CSF).
Main Methods:
- Clinical examination of four Southdown ewes with suspected scrapie.
- Cerebrospinal fluid (CSF) analysis for cell counts and protein concentration.
- Immunoassay for 14-3-3 protein in CSF.
- Prion protein (PrP) gene sequencing to determine genotype.
- Histopathological and immunohistochemical examination of brain tissue.
Main Results:
- All four ewes exhibited clinical signs consistent with scrapie.
- CSF analysis showed elevated protein levels and variable cell counts.
- 14-3-3 protein was detected in the CSF of three out of four sheep.
- All sheep were homozygous for glutamine at codon 171 (QQ genotype).
- Histopathology revealed neuronal vacuolation and spongiform changes, confirmed by PrP staining.
Conclusions:
- Naturally occurring scrapie in Southdown sheep shares genetic susceptibility (QQ genotype) with Suffolk sheep.
- Clinical signs, CSF abnormalities, and PrP gene sequencing aid in scrapie diagnosis.
- Further research is needed to fully understand scrapie pathogenesis in Southdown sheep.