Review: update on classical and atypical scrapie in sheep and goats

Authors: Greenlee, Justin

Submitted to: Veterinary Pathology
Publication Type: Review Article
Publication Acceptance Date: 7/10/2018
Publication Date: 9/10/2018
Citation: Greenlee, J.J. 2018. Review: update on classical and atypical scrapie in sheep and goats. Veterinary Pathology. 56(1):6-16. https://doi.org/10.1177/0300985818794247.
DOI: https://doi.org/10.1177/0300985818794247

Interpretive Summary: Scrapie is a fatal disease of sheep and goats that causes damaging changes in the brain. The infectious agent is an abnormal protein called a prion that has misfolded from its normal state. This manuscript reviews the importance that the prion protein amino acid sequence has on the potential susceptibility of a sheep or goat host and how distribution of the abnormal prion protein in host tissues is critical to potential environmental contamination with prions. A portion of the manuscript is devoted to how to differentiate classical strains of scrapie that readily spread amongst susceptible hosts from atypical scrapie, which is thought to be a spontaneous rather than infectious disease. This information is useful to individuals in the sheep and goat industries, veterinarians, and veterinary pathologists.

Technical Abstract: Scrapie is a naturally occurring transmissible spongiform encephalopathy (TSE) or prion disease of sheep and goats. Scrapie is a protein misfolding disease where the normal prion protein (PrPC) misfolds into a pathogenic form (PrPSc) that is highly resistant to enzymatic breakdown within the cell and accumulates eventually leading to neurodegeneration. The amino acid sequence of the prion protein and tissue distribution of PrPSc within affected hosts have a major roles in determining susceptibility to and potential environmental contamination with the scrapie agent. A major distinction can be made between classical scrapie strains that are readily spread within populations of susceptible sheep and goats and atypical (Nor-98) scrapie that has unique molecular and phenotype characteristics and is thought to occur spontaneously in older sheep or goats. This review provides an overview on classical and atypical scrapie in sheep and goats with mention of potential transmission of scrapie to other mammalian hosts.