TSE Flashcards
give examples of TSEs
sheep and goats: scrapie, atypical scrapie
Mink: minl spongiform encephalopathy
Deer/elk: chronic wasting disease
Cattle: bovine spongiform encephalopathy
cats: feline spongiform encephalopathy
what are Transmissible spongiform encephalopathies
- neurological disorders
- neuronal loss
- invariably fatal
- very long incubation periods
- caused by misfolded prion protein
discuss the role to prions in the development of TSEs
PRPc, a prion protein found in all mammals and has no known function, but high levels of expression within the CNS, misfolds. the prion, which is mainly composed of alpha helixes, changes conformation to beta sheets which makes the protein more rigid. this can happen one of three ways:
- spontaneously
- inherited (genetic)
- acquired (ingestion, contact)
it is not treatable, there is no cure and it can have VERY long incubation periods (time from exposure to symptoms)
what are some properties of prions
‘Especially in terms of removing them from environments or animals
- relatively insoluble
- self catalytic conversion
- exceptionally high stability
- resistant to proteases
- resistant to heat treatment
- resistant to UV
making it difficult to decontaminate premises or clinical setting and allowing it to survive in environmental reservoirs
there is NO CURE or TREATMENT
how do you test for TSEs
the primary site of pathogenetic prions is found in the obex, a site in the brain stem caudal to the medulla oblongata.
HOWEVER, different strains have been found in the cerebrum and cerebellum instead.
only way tp test definitively is with post mortem sample of brain
tests: histology, immunohistochemistry, Immunoassays (Western blots and ELISAs)
what are clinical signs of TSEs
- weight loss
- subtle behavioural chanhes
- licking lips, grinding teeth, scratching
- pruitis (scrapie)
- posture, gait changes
- ataxia/tremors
- none, animal found dead
which strain of TSE is zoonotic
BSE and FSE
how is TSEs spread
BSE, FSE etc are difficult to spread among hosts (requires ingestion, transmission via medical procedure)
Scrapie and CWD are transmitted through direct contact an environmental reservoirs
how is TSE controlled
- culling/cohort culling
- feed ban for ruminant material
- older cattle banned from human food chain
- ban of specific risk material from food chain
- export ban
- surveilance
- breeding resistant genotype
what are contagious materials for scrapie in sheep
- skin
- feces
- urine
- saliva
- placenta (very contagious)
- blood
- milk
