What does the term prion mean?
“Infectious protein” or “rogue protein”
What is a characteristic of ALL prion diseases?
Spongiform degeneration of the grey matter of the brain
Causing **transmissible spongiform encephalopathies
What are prions?
Normal cellular proteins that have undergone conformational changes and have become pathogenic
What is PrPc?
The normal protein (before it transformed into a prion) alpha helices structure
Where are prions most commonly expressed?
Neurons and lymphoreticular cells
What is the PrPsc?
The abnormal protein - prion (beta sheet structure)
**has a change in conformation from the normal protein that makes it pathogenic
T/F: amino acid sequences of PrPc and PrPsc in a given host are identical
Who discovered the prion?
Who discovered the kuru prion?
T/F: Prions induce inflammatory or immune responses in hosts
They DO NOT induce inflammation or immune response
**therefore looking for antibodies will not be a logical dx test – none will be made
T/F: Prions are resistant to chemical and physical conditions, such as UV rays
What are PrPsc aggregates in cells called? (build of of these cells)
Scrapie associated fibrils (SAF)
**can reach high titers
How do prions replicate
Normal protein becomes prion protein - then these will accumulate since they are very resistant
The PrPsc catalyses the conversion of PrPc into PrPsc
Who does Scrapie dx infect?
Suffolk and Hampshire sheep breeds are more susceptible
What is the mode of transmission of scrapie?
Contamination of wounds with placental tissue or body fluids
maybe vertical transmission
What clinical signs might you see in a sheep with Scrapie?
Weight loss, pruritus, loss of wool, ataxia, paralysis of hind limbs
What might you see on histo of a brain infected with Scrapie?
Neuronal vacuolation and degeneration
astrocytic hypertrophy and hyperplasia
*no inflammatory reaction
How do you tx scrapie?
Eliminate the animal
How do you dx scrapie?
cased on clinical signs and histopath of brains (immunohistochemistry)
western blot of brain tissue
*ante-mortem sampling of lymphoid tissue of nictitating membrane, tonsils, or rectal mucosa
What dx does Bovine spongiform encephalopathy (BSE) cause?
MAD COW DISEASE
How is it transmitted?
Through ingestion of infected meat/bone
What clinical signs might you see in a cow with BSV?
**mostly in cows 3-5yrs old
temors, decreased milk production, abnormal posture, wt loss, aggression, hind limb ataxia and paralysis
How long does it typically take mad cow dz to become fatal?
2-3 weeks, up to 1 year after onset of clinical signs
can humans become infected with mad cow dz?
YES!! and cats too
What will be seen on histo of a cow with made cow dz?
neuronal vacillations, degeneration and loss of neurons, astrocytic hypertrophy and hyperplasia, lesions in midbrain, brain stem, cervical spine (Test the pons)
Lesions are MININAL in cerebral cortex, cerebellum, hippocampus
T/F: There are diagnostics established to test for BSE before clinical signs
Dx is based on clinical signs, herd history, immunohistochemistry of brain sample