TSE/BSE Flashcards
Give examples of TSEs of animals
- Scrapie (Sheep and goats)
- Chronic wasting disease (Deer and elk)
- Bovine Spongiform Encephalopathy (Cattle, Cats, Goats and exotic ungulates )
What are TSEs
Definition
Transmissible Spongiform Encephalopathy
What are TSEs
- Neurological disorders
- Neuronal loss
- Invariably Fatal
- Very long incubation periods
What causes TSEs
Misfolded prion protein (PrPsc)
When was BSE first identified in UK cattle
1986
Describe the control measures put in place because of the BSE out break
- Culling, cohort culling (cows on the farm born 2 years before and after the birth of the infected cow)
- Feed ban for ruminant material
- older cattle banned from food chain
- ban on specified-risk material from food chain( CNS)
- export ban
- surveillance
Clinical signs of TSEs
- weight loss
- behaviour changes (hypersensitive)
- licking lips, grinding teeth, scratching
- pruritus (itching just scrapie)
- posture, gait
- Ataxia, tremors
- None, sometimes animal just found dead
Why are TSEs hard to diagnose with clinical signs
The clinical signs don’t specifically show that it is a TSE could be different disease causing these issues
Describe the properties of prions
- convert normal PrPc to PrPsc
- relatively insoluble
- exceptionally high stability for protein
What are prions resistant to
- proteases
- heat treatment
- UV
Describe the issues cause by prions high stability
- can’t easily decontaminate premises or in a clinical setting
- can survive in environmental reservoirs for many years
Where is the primary site for pathogenic prions in the brain
- The obex (caudal part of the medulla)
Describe the composition of PrPc
(Normal)
Rich in alpha helices
Describe the composition of PrPsc
Rich in beta pleated sheets
Have some alpha helices
Misfolded protein
How does infection by PrPsc occur
- ingestion of PrPsc contaminated feeds
- Horizontal transmission during perinatal period
- Superfical abrasion s
- Environmental
How is a TSE diagnosed
A diagnosis of TSE can only be made b demonstrating the presence of prion protein (has to be done post mortum )
Describe the TSE confirmatory test most used
Immunoassays- western blots and ELISAs (rely on the protease resistance of PrPsc compared to PrPc)
Positive test= 3 bands produced
Are TSEs Zoonotic
BSE= Zoonotic CWD= unlikely to be zoonotic Scrapie = non-zoonotic
Explain the economic impact of TSEs in the uk
- loss of income for agriculture/ government compensation
- export ban
- collapse of home market for beef
- lower market for milk/ lamb
- cost of surveillance
- cost of research
