Prion diseases Flashcards
What is a prion?
Misfolded protein that can cause neurodegenerative diseases by inducing abnormal folding of normal cellular proteins
What makes prions unique compared to other infectious agents?
Unlike viruses, bacteria, or parasites, prions contain no nucleic acid
Their infectivity & pathology are determined by protein conformation rather than genome
What is the normal cellular prion protein (PrP𝐶)?
Benign cellular protein found on outside of mammalian cells
Exact function unknown but is highly expressed in neuronal tissue
How does PrP𝐶 become a pathogenic prion (PrPSc)?
Misfolding of PrP𝐶 converts it into PrPSc which can then bind to more PrP𝐶 & trigger further misfolding
PrPSc aggregates into fibrils, accumulating in neuronal tissues, leading to cell death & pathology
How can prion diseases arise?
Spontaneous: Occurs in older animals due to random misfolding
Inherited: Some genetic variants of PrP𝐶 misfold more easily, increasing susceptibility
Acquired: Ingestion of PrPSc from contaminated feed or food, leading to its accumulation in neuronal tissues
What are prion diseases also known as?
Transmissible spongiform encephalopathies (TSEs)
What are key characteristics of prion diseases?
Neurological disorders with neuronal loss
Invariably fatal with no treatment or cure
Very long incubation periods (e.g. 2-4 years in sheep, 2-7 years in cattle)
What histopathological changes occur in prion-infected brain tissue?
Spongiform holes indicating neuronal degeneration & vacuolation
What are some veterinary prion diseases?
What are common clinical signs of prion diseases?
Weight loss
Behavioural changes (isolation, flightiness)
Pruritus (scrapie)
Ataxia, tremors
Altered posture/gait
Sometimes sudden death
What caused the BSE epidemic?
How is classical scrapie controlled?
Through National Scrapie Plan, which focuses on breeding programs & surveillance
Where has CWD been detected in Europe?
In European cervids, raising concerns about its spread
Why is surveillance important for prion diseases?
New strains can emerge, potentially posing zoonotic risks; farm outbreaks of scrapie & isolated BSE cases still occur
