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422 Virology > lecture 18- prions > Flashcards

lecture 18- prions Flashcards

1
Q

What are the differences between a virus and a prion?

A

Prions: no genetic info, protein only, no adaptive immunological response

viruses: contain gene info, DNA/RNA, protein, some with lipid coat, immunological response

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2
Q

what disease was involved with identifying prions?

A

scrapie

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3
Q

what does prion actually mean

A

proteinaceous infectious particle

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4
Q

why does UV kill viruses, but not prions?

A

UV interacts with DNA/genetic info- prions do not have nucleic acid

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5
Q

What is the protein-only hypothesis?

A

prions self-replicate without nucleic acid by converting a normal protein into a misfolded, infectious form

infectious agent is protein, versus nucleic acid

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6
Q

How do prions replicate?

A

cellular prion protein undergoes a conformational change to become disease prion protein (ex PrPc becomes PrPsc) –> misfolded protein is what accumulates

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7
Q

What are the different etiologies of prion diseases?

A

sporadic (most common), inherited, acquired

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8
Q

what is the most common etiology of prion disease in humans?

A

Sporadic Creutzfeldt-Jakob disease (CJD) (85-90% of all human cases)

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9
Q

examples of prion diseases?

A

mad cow, scrapie, kuru, chronic wasting disease, creutzfeldt-jakob disease

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10
Q

what do all prion diseases have in common? 6 things

A

Fatal
Transmissible/infectious
Spongiform neurodegeneration
Long incubation time
Short clinical phase
No treatment or prophylaxis available

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11
Q

What are the most important animal prion diseases?

A

scrapie (sheep and goats)
BSE (cattle)
CWD (elk and deer)

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12
Q

what changes are seen with classical scrapie

A

behavioural
Incoordination
Tremor
Ataxia
Pruritus

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13
Q

where are infectious prions found / shed with scrapie?

A

Prions found in urine, saliva, feces, milk

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14
Q

what is different about atypical scrapie?

A

Pruritus is uncommon (ataxia and incoordination is common), different /diffuse distribution in brain (not in opex)

found in more than 20 European countries, The Falkland Islands, USA, New Zealand,
Australia, Canada

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15
Q

What to do if you suspect a prion case – what material is needed for diagnosis?

A

mainly brain homogenates (obex region of brain stem), in some cases biopsies (ante mortem) rectoanal mucosa-associated lymphoid tissue
(RAMALT), retropharyngeal lymph node (CWD and scrapie)

must detect misfolded protein (PRPsc) (must detect protease resistant prion protein)

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16
Q

Which tests are used for diagnosis and what is detected?

A

immunoblot (western blot) - look for protease resistant prion protein

ELISA- detects PrP sc

immunohistochemistry/histopathology - antibody-based detection of PrPSc in tissue slices

17
Q

Are prion diseases zoonotic?

A

YES

18
Q

true or false: PrPc and PrPsc have a different amino acid sequence

what is the significance of this regarding antibody response?

A

false - it is the same

antibodies cannot differentiate cellular from scrapie

19
Q

can you use PCR to detect prions?

A

noooooo same primary structure/ AA sequence

20
Q

can you select against scrapie?

A

yes, you can select against classical scrapie BUT not atypical scrapie

still reduces scrapie though

21
Q

what are clinical signs of classical BSE?

A

behaviour (Anxiety, Teeth grinding, Frequent nose licking, Tremors), sensory system (hypersensitive to touch, noise, light), locomotion (ataxia, hypermetria, cannot get up)

22
Q

true or false- BSE is transmitted by contact (is contagious)

A

FALSE - BSE does not have prion shedding (stays in brain)

transmitted by ruminant-derived meat and bone meal (‘neo-cannibalism’)

23
Q

when was the most recent case of classical BSE in alberta detected

A

feb 2015

24
Q

what animal is resistant to BSE ???

A

dogs !

25
Q

who is naturally susceptible to BSE

A

humans, cats, exotic ungulates, (and cattle obvi)

26
Q

what are 3 significant differences with variant Creutzfeldt-Jakob disease (vCJD) versus sporadic Creutzfeldt-Jakob disease (sCJD)

what is the significant of CJD

A
  • Median age at death: 28 years (versus 68)
  • Clinical phase: 14 months (versus 6 months)
  • Ataxia, psychiatric symptoms (versus dementia)

CJD is disease humans get from BSE

27
Q

what types of BSE are there?

A

classical
H type atypical
L type atypical

28
Q

what is significant about chronic wasting disease?

A

infects wild living and farmed animals

29
Q

how is CWD transmitted

A

horizontal and vertical – oral infection

30
Q

what are the clinical signs of CWD?

A

progressive weight loss
behavioral changes
depression and isolation
hypersalivation
teeth grinding
lack of coordination
difficulty swallowing
extreme thirst and urination
pneumonia

31
Q

what is the most contagious prion disease?

A

chronic wasting disease

32
Q

true or false: the camelid prion disease has a different molecular signature than BSE and scrapie

A

true

422 Virology (15 decks)

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