Prions Flashcards
What is the definition of prions?
Small, proteinaceous infectious particle that resists inactivation by procedures that modify nucleic acids
What is the mechanism by which prions work?
Mutant protein (PrPsc) has same amino acid as normal protein (PrPc), just different folding Mutant can make normal protein change folding to become mutant structure
What is the disease caused by prions?
Transmissible spongiform encephalopathy
What are clinical presentations of spongiform encephalopathy?
Loss of motor control, dementia, paralysis wasting and eventually death, typically following pneumonia
What animal is infected with Scrapie?
Sheep
What are histological characteristics of spongiform encephalopathies on autopsy?
Vacuoles in cerebellum and cortex
Amyloid deposits
Astrocytosis
Can also stain for prions now
What diseases are in the category of inherited TSEs?
Familial Creutzfeldt-Jacob Disease (CJD)
GSS
Fatal Familial Insomnia (FFI)
What diseases are in the category of spontaneous TSEs?
Spontaneous Creutzfeldt-Jacob Disease
Fatal Sporadic Insomnia (FSI)
What diseases are in the category of infectious TSEs?
Kuru (ritualistic cannibalism)
New Variant CJD (nvCJD; from bovine prions)
What is the name of the normal form and of mutant form of the prion protein?
PrPc - normal
PrPsc - mutant
What are the two proposed models of prion propagation?
Refolding model - conversion between PrPc and PrPsc prevented, requires induction
Seeding model - equilibrium between PrPc and PrPsc, seed formation of more PrPsc
Which is more efficient, prion infection in same species or different species?
Same species
How are prion disease transmitted?
Acquired (infectious): diet, medical procedures involving contaminated instruments, growth hormone injections, transplants
Inherited: mutated PrPc better allow conversion to PrPsc
Spontaneous: PrPc -> PrPsc
When are prions beneficial?
In yeast - allows switch between phenotypic states and better survive stressful environment (increased fitness)
