Prion Diseases Flashcards
What is a prion?
Proteinaceous infectious particle
No nucleic acid involved
Misfolding of PrPC molecule to form PrPSc
* Spontaneous in older animals
* Inherited
* Acquired by ingesting
PrPC
Cellular prion protein
Bening
Found on outside of cells
Unknown function
Expressed greatly in CNS
How does prion disease occur
- PrPC protein misfolds to form PrPSc
- PrPSc binds to PrPC to form more PrPSc
- PrPSc aggregates into large fibrils in neuronal tissue
- Results in cell death and pathology
- Sponge appearance
Why are prion diseases neurological
Prions are expressed greatly in CNS
Causes neuronal loss
No treatment/cure
Long incubation periods
○ 2-4 years in sheep
○ 2-7 years in cattle
Prion disease in sheep
Scrapie - endemic in UK population for 100s of years
* Recently under control
Atypical scrapie
* More recently discovered
* More of a problem
Prion disease in Deer/elk
Chronic wasting disease
Prion disease in cattle
Bovine Spongiform Encephalopathy
* First zoonotic recorded prion disease
Don’t secrete prion into environment
TSE
Transmissible Spongiform Encephalopathy
All notifiable diseases in farm animals
Neurodegenerative diseases
Prion disease in cats
Feline Spongiform Encephalopathy (BSE)
Prion disease in humans
Variant Creutzfeldt-Jakob disease (vCJD)
Caused by eating meat contaminated with BSE
Clinical signs of TSEs
- Weight loss, subtle behavioural changes
○ E.g. isolated, flighty, lies down more, dull - Licking lips
- Grinding teeth
- Scratching
- Pruritus
○ Scrapie - Posture, gait
- Ataxia, tremors
- None - animal found dead
Significance of TSEs
All notifiable diseases
Fatal
No cures/treatments
Expensive to farming community
* Need to cull infected animals
National Scrapie Plan
○ To breed sheep for PRNP gene which was highly resistant to classical scrapie
○ Very successful - scrapie cases reduced
○ Now very few cases of classical scrapie
No genetic resistance in goats
Still susceptible to atypical scrapie
