Prions Flashcards
Definition of prion
infectious protein
Different animals can have prion diseases. In humans, there are 5 recognized ones.
- Kuru
- Fatal Familial Insomnia
- Gerstmann-Stassler-Scheinker syndrome
- variant Cretzfeldt-Jacob Disease (vCJD)
- Creutzfeldt-Jacob Disease (CJD)
CJD is the most common prion disease in humans. What are some causes?
- sporadic (sCJD) -no known cause accounting for 85-95%)
- familial (fCJD) -inherited risk (7-10%)
- iatrogenic (iCJD) -exposure during medical procedures (<1%)
Is sCID related to human “mad cow disease”
No, it is not what we know today as mad cow disease
T/F: sCJD can be transmitted person-to-person by blood transfusion or meat contaminated with BSE.
False
Symptoms of sCJD
- spongiform encephalopathy
- loss of brain function resembles Alzheimers, but occurs RAPIDLY
- complete dementia usu. occurs by the 6th month
- death occurs within one year of symptom onset
What are the two cardinal symptoms and signs of sCJD?
1) mental deterioration -delirium, dementia, mood changes
2) myoclonus -muscle twitching, provoked by startle
What causes prion diseases?
Protein-only hypothesis (not caused by microbes b/c lack of immune response)
Prions are encoded by the host by which gene?
PrPc gene (cellular form) is involved in maintaining brain’s white matter, neuron formation.
Protein misfolding converts PrPc to
PrPsc (scrapie form) -beta sheet
T/F: PrPsc can be experimentally transmitted to animals
True
There are 4 types of PrPsc. How can you tell them apart?
Different results when in proteinase K
- Type 1 is associated with sCJD
- Type 4 is associated with vCJD
How to diagnose prion diseases?
-Brain biopsy using hematoxylin and eosin stain of thin brain section
How to characterize sCJD in biopsy?
1) spongiform change
2) neuronal loss w/o inflammation
3) accumulation of PrPsc
Electroencephalography (EEG) and MRI are normal or abnormal in someone with sCJD?
Abnormal
