Lecture 23 Flashcards
What is a prion
A proteinaceous infectious agents
What is transmissible spongiform encephalopathies
A group of inevitably fatal neurodegenerative diseases found in a wide range on mammals
What does TSEs result from
The conformational conversion of a normal cellular prion protein into an abnormal misfiled pathological form
What does accumulation of PrP^Sc lead to
The onset of TSEs, which attack the CNS, resulting in progressive neuronal degeneration and neuronal vacuolation
What gene is the prion protein produced by
PRNP gene
Explain the pathogenesis of TSEs
The defective prions induce other prion molecules to misfiled in a self-sustaining feedback loop
Where does Creutzfeldt-Jakob disease occur
Worldwide
What are Creutzfeldt-Jakob disease symptoms
Ataxia, dysarthria, dysphagia, nystagmus, myoclonus and dementia
What are 85-90% of TSEs cases caused by
Sporadic CJD
Two hypothesis for the origins of Bovine Spongiform Encephalopathy
- BSE originated as a spontaneous PrP^Sc mutation in cattle
- That it came from a mutated scrapie prion that contaminated ruminant feed
Does cooking and standard disinfectant destroy infectious prions
No
Where do prions replicate
Peyer’s patches of the ileum and then transported via the peripheral nerves to the CNS
Is BSE transmissible by milk, semen or embryos
No
Clinical signs of BSE
- gait abnormalities and difficulty negotiating obstacles, low carriage of the head, hyperresonsiveness to stimuli and tremors
- Behavioural changes such as aggression, nervousness or apprehension, changes in temperament and even frenzy
What is BSE diagnosed by
- Characteristic histopathology changes in the brain
2. Detecting prions in the CNS using immunostaining methods
How is Variant Creutzfeldt-Jacob disease transmitted
- Eating BSE prions in contaminated animal tissue
- Several patients were infected by blood transfusion
- Transplantation
What is feline spongiform encephalopathy caused by
The same prion agent that causes BSE
What is scrapie
Neurodegenerative disease that affects sheep and less frequently goats
How is scrapie transmitted
Between animals either directly or via the environment
What are the first signs of scrapie
Affected sheep tend to stand apart from the flock and not follow usual flocking behaviour
How is scopes transmitted
Infected animals carry the scrapie prion for life and can transmit the agent even if they remain asymptomatic
What does chronic wasting disease infect
Deer, elk, reindeer, sika deer and moose
