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18 Cards in this Set

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What is another name for Prion disease?
Transmissible spongiform encephalopathy.
Why are the diseases considered spongiform?
They create spongiform pathological changes in the brain resulting in encephalopathic deterioration.
What are 2 well known veterinary diseases of prionic origen?
1. Scrapie, in sheep and goats
2. BSE, bovine spongiform encephalopathy
List 4 human prion diseases.
1. Creutafeldt-Jakob disease
2. Kuru (shivering)
3. Gerstmann-Straussler-scheinker(GSS)
4. fatal familial insommnia(FFI).
List several characteristics of prion diseases?
1. Long incubation time
2. Gradual increase in severity
3. No host immune response
4. Non inflammatory response in the brain
5. Spongiform changes with microscopic vacuoles with amyloid plaques with accumulation of prion protein(PrP)
prion diseases are unique in being both inherited and infectious. TRUE/FALSE
TRUE.
What are the two main theories or hypothses regarding prions?
1. protein only hypothesis-infectious agents consists only of prion proteins with little if any nucleic acid.
2. Viral hypothesis-It remains possible for prions to contain extremely small amounts or protected nucleic acid.
Can prions be infectious if they do not contain nucleic acid?
Though the protein only theory is more widely accepted,it turns out that PrP is encoded by an endogenous gene(located on chromosome 20 in humans), yet exists in two conformational isoforms, that is PrP has two different(2ary and 3ary) protein structures.
What is the cellular isoform of PrP?
It is constitutively expressed by normal animals, especially in the brain and is called PrP(c) for cellular. Its function is unknown.
The disease associated isoform of PrP is called PrP(sc)
What's the difference between the normal PrP(c) and PrP(sc)?
The conformation(structure) of PrP(sc) is different from PrP(c) and is thought to be responsible for the development of disease; Aberrent metabolism of PrP(sc) results in accumulation of the protein and brain injury.
What is the result of PrP(c) conformational change?
It is thought to be post-translational and can be apparantly induced by the presence of PrP(sc), maybe with the interaction of other proteins. A small amount of PrP(sc) will initiate a chain reaction of conformational change of PrP(c) into PrP(sc).
The prions do not need the genetic software in the infectious particle, its already present in the host as part of the genome. TRUE/FALSE
TRUE. The amino acid sequence of the sick isoform of PrP(sc) accumulating in a patients brain is encoded by the PrP gene of that individual.
Contaminated neural tissue has been shown to transmit disease even across species barriers. Transmission can be inocular or oral. TRUE/FALSE
TRUE. The organisms have proven to be extraordinarily resistant to most methods of sterilization.
What would cause or has caused the BSE epidemic among cattle?
It is attributed to the practice of feeding cattle(contaminated)sheep offal(meat and bone meal).
sale of meat on the bone(T-bone steaks) has been banned to reduce the contamination risk from neural tissue.
Iatrogenic cases of CJD, have been established through contaminated(neuro surgical instruments, dural and corneal grafts and administration of cadaveric pituitary hormones. TRUE/FALSE
TRUE.
How is Prion disease diagnosed?
The gold standard is histopathlogic examination and immunostaining for PrP(sc) of brain tissue.
CSF is normal except that proteins are slightly elevated. certain proteins(14-3-3 and S100 proteins may occur in the CSF. This method is not specific for prion disease.
PrP is also present in lymphoreticular tissue and the utility of tonsil and spleen biopsies are under investigation. TRUE/FALSE
TRUE.
Is there a treatment for Prion disease?
There is none at this time.