Prions Flashcards
Prions Definition
Are not viruses but are single proteins found in the nervous system on the surface of neurons in the brain.
Prions contact and induce a normal cellular protein to change shape and to become a prion protein.
“Infectious protein” hypothesis: Prions (PrPres) turn only their own cellular counterpart (PrPC) into prions and do not affect other proteins.
Diseases Caused by Prions
Transmissible Spongiform
Encephalopathies (TSE)
Bovine spongiform encephalopathy (BSE) - Mad Cow Disease.
Can be transmitted by feeding cow meat and bone meal to other cows. Strict rules govern animal feed and screening of animals is done.
Scrapie - Sheep, goats
Chronic wasting disease (CWD): deer, elk, antelope.
- transmitted through cuts in the skin.
Creutzfeldt-Jakob disease in humans rare, degenerative, invariably fatal brain disorder. About one per milllion persons. Can be sporadic, hereditary or acquired sporadically in at least 85% of cases; eating diseased animal
Kuru - cannibalism - eating human brains - Papua New Guinea
Diagnosis of Prion disease
Patients referred due to behavioral changes.
Must rule out other causes of dementia including treatable encephalitis and meningitis.
Diagnosis is by protein detection from biopsies or by brain sectioning on autopsy.
Prions induce no immune response, so there is no diagnosis by detection of antibodies.
There is no treatment.
Prions are resistant to what?
Routine autoclaving Proteases Organic solvents Alkaline cleaners UV light Radiation Ethanol Formaldehyde
To inactivate: 1N NaOH or undiluted bleach
+ autoclaving at 121°C for 1 hour
