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Clinical Examination Protocol to Detect Atypical and Classical Scrapie in Sheep
Published on: January 19, 2014
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Classical scrapie transmission in ARR/ARR genotype sheep
Caroline Lacroux1, Hervé Cassard1, Hugh Simmons2
1UMR INRA-ENVT 1225, 23 Chemin des Capelles, 31076 Toulouse, France.
The Journal of General Virology
|July 20, 2017
Summary
Sheep with the ARR allele are not fully resistant to classical scrapie. This study found clinical disease in ARR/ARR sheep, though transmission was limited, indicating scrapie
Area of Science:
- Veterinary Medicine
- Animal Science
- Neuroscience
Background:
- The ARR allele in sheep is widely believed to confer strong resistance to classical scrapie.
- Transmissible spongiform encephalopathies (TSEs) pose significant challenges in animal health and food safety.
Purpose of the Study:
- To investigate the susceptibility of ARR/ARR sheep to classical scrapie.
- To evaluate the transmission dynamics and adaptation of classical scrapie in sheep with the ARR genotype.
Main Methods:
- Intracerebral inoculation of ARR/ARR sheep with a classical scrapie isolate.
- Passage of the prion agent to assess transmissibility and incubation periods.
- Comparison with ARQ/ARQ sheep challenged with the same isolate.
Main Results:
- Clinical transmissible spongiform encephalopathy occurred in ARR/ARR sheep after prolonged incubation periods (over 6 years) on first passage.
- Second passage of the prion agent did not enhance its propagation ability in ARR/ARR sheep.
- In contrast, ARQ/ARQ sheep exhibited a 100% attack rate and shorter incubation periods.
Conclusions:
- ARR/ARR sheep are not completely resistant to classical scrapie, challenging previous assumptions.
- Classical scrapie demonstrates a limited capacity for transmission and adaptation in sheep with the ARR genotype.
- These findings underscore the complexity of prion disease resistance and transmission in sheep.
