Introduction to Prions (2) Flashcards
What are prion diseases called?
Transmissible Spongiform Encephalopathies (TSEs)
What diseases do TSEs cause?
Unique group of progressive fatal neurodegenerative disorders.
Are prions transmissible?
yes
What causes TSEs?
Caused by accumulation of an abnormal form of a naturally occurring protein (‘prion’ protein, PrPc) in the brain.
Neuronal loss, astrocyte proliferation, and vacuolation of the brain leading to a spongiform appearance.
What is the incubation period for an individual with TSEs?
Variable incubation periods (60 days - years).
Are TSEs treatable?
no
What is aetiology?
the cause, set of causes, or manner of causation of a disease or condition.
What are the 3 main forms of human prion diseases (distinguished by aetiology?)
genetic
sporadic
acquired
How is a prion genetically made into a disease causing form?
mutations is the prion encoding gene (PRNP)
What is the aetiology of the sporadic prion form?
unknown
possibly spontaneous protein change
What is the aetiology of the acquired prion form?
Transmission of disease from an animal or person-to-person.
What is the most common group of prion diseases?
sporadic prion diseases
spontaneous confo change
How are sporadic prion disease transmitted?
May be transmitted iatrogenically.
What are the 3 main forms of acquired prion disease?
Kuru: confined to Papua New Guinea (historical importance) transmission by ritualistic cannibalism
Variant CJD (vCJD): resulting originally from Bovine Spongiform Encephalopathy (BSE) contamination of food.
Iatrogenic CJD: CJD transmitted accidentally during the course of medical or surgical procedures.
What is the bovine spongiform encephalopathy?
cow form of the scrappie infected cows
mad cow disease
What is vCJD?
Evidence vCJD transmitted from BSE in cattle to humans via food (primary transmission).
acquired
What is iatrogenic CJD?
CJD transmitted accidentally during the course of medical or surgical procedures.
How do most cases of iatrogenic CJD arise?
- Most cases arisen from contaminated human growth hormone treatment in children or human dura mater grafts.
- Few cases from corneal transplantation, neurosurgery and specialised brain electrode techniques.
- At least four cases from blood transfusion.
Where is vCJD in humans demonstrated (iatrogenic and variant)?
PrPsc demonstrated in tonsils, spleen and lymph nodes in vCJD.
Can iatrogenic CJD as risk of human to human transmission?
Risk of human to human transmission through medical procedures including the use of blood and blood products.
What is the effect on the human brain of Prpsc?
shrinkage
