BSE, CJD and Prions Flashcards

1
Q

BSE

A

Bovine Spongifory Encephalopathy

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2
Q

CJD

A

Creutzfeld Jakob Disease

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3
Q

TSE

A

Transmissable Spongiform Encephalopthay

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4
Q

What are TSEs?

A

rare forms of progressive neurodegenerative disorders that affect both humans and animals

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5
Q

What are TSEs caused by?

A

Prions

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6
Q

What changes occur in the brain?

A

spongiform - severe atrophy

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7
Q

What is the incubation period?

A

2-8 years from infection

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8
Q

What is the deterioration period in cows?

A

2 weeks to 6 months

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9
Q

What is the first phase of BSE?

A

low infectivity rate and cow is not a threat to humans

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10
Q

What is the second phase of BSE?

A

cow is very infective but symptoms not apparent

prion is abundant in brain and spinal cord

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11
Q

What is the third phase of BSE?

A

clinical symptoms followed by death

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12
Q

What changes may be seen in an affected cow?

A

changes in temprament, nervousness or aggression, abnormal posture, inco-ordination or difficulty rising, decreased milk production or weight loss

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13
Q

How is BSE diagnosed?

A

via pathology post mortem

microscopic look at brain tissue or detection of abnormal prion protein

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14
Q

What histological findings exist in BSE?

A
  • vacuolation of neurons and neuronal ground substance in cerebella and cortex
  • perivascular fibrils of amyloid in PrPsc - immunostaining
  • astrocyte infiltrations
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15
Q

When was BSE first identified in Britain?

A

1985

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16
Q

What was considered the cause of BSE in the UK?

A

use of meal and bone mill feed (contained infected brain and spinal cords of sheep with scrapies)

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17
Q

How did BSE spread to humans?

A

large companies used dairy cattle and fatted up their burgers for taste using spinal cord and brain of infected cattle

18
Q

what is vCJD?

A

BSE in humans, mostly young patients, 1996 onwards - about right time period

19
Q

what are the symptoms of CJD?

A

loss of expressiveness
muscular tremble
spasm
loss of memory & dementia (rare in vCJD)

20
Q

What are the features of CJD caused by eating the cattle products?

A

increased risk of CJD - most cases in 2001

predominantly in 20-30 years

21
Q

What are the clinical features of CJD?

A

67years, 4 months to live, dementia common, rarely psychiatric issues

22
Q

what are the clinical features of vCJD?

A

29years, 13 months to live, dementia is rare, psychiatric illness common

23
Q

What is the most important variation in prion proteins?

A

at 129 where it can be a valine or methionine (worse if homozygous)

24
Q

What are the features of Kuru?

A

found in papa new guinea
due to cannabilism of the dead
causes fatal cerebellar ataxia
with kuru plaques which are amyloid-like

25
Q

What are the forms of CJD?

A

classic and variant

26
Q

What is a feature of classic CJD?

A

can be transmitted to other species but they cannot carry it

27
Q

How is CJD sub-classified?

A

sporadic >85% cases or iatrogenic (caused by healthcare)

28
Q

what mutation do the majority of iatrogenic cases have?

A

90% homo 129 Methionine

29
Q

How are familial forms of CJD influenced?

A

by polymorphisms in the 129 Val/Meth

30
Q

What are the forms of familial CJD?

A

Familial fatal insomnia

GSS

31
Q

What occurs in FFI?

A
4-6th decade
autosomal dominant
129 Met leads to FFI
Val -> CJD
insomnia, ataxia and dementia
32
Q

What occurs in GSS?

A

autosomal dominant
PrP mutation Proline 102-Leucine
further influenced by polymorphism

33
Q

What is the pathology surrounding SEs?

A

spongiform degeneration
neuronal loss
astrocytic proliferation
anatomical distribution varies between forms of TSE

34
Q

What are prions?

A

shortened forms of proteinacious infections particles 250aa

abnormal variants of a protein with normally occurs in a cell PrPc

35
Q

What do abnormal prions do?

A

convert normal forms that they come into contact with PrPc->PrPsc

36
Q

What is the result of the continual conversion of PrPc?

A
  • clusters of tangled, non-functional proteins in plaques

- neuronal apoptosis

37
Q

What causes the spongiform degeneration?

A

when the immune system removes the neurons and PrPsc aggregates

38
Q

What makes prion diseases so difficult to target?

A
resistant to digestion
can't be targeted with antibiotics or anti-virals
heat resistant
no immune response
difficult to decompose biologically
39
Q

What are the neuropathological criteria for vCJD?

A
  • multiple florid plaques with eosin staining
  • severe spongiform changes in caudate nucleus and putamen
  • marked astrocytosis and neuronal loss in posterior thalamic nuclei
  • PrPsc accumulation in lymphoid tissue around the body
40
Q

What has been found in the 129 polymorphism in vCJD?

A

100% have MM at polymorphism

41
Q

How many sporadic cases of CJD have MM?

A

65%