Prion Disease

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Prion Disease Viroid
NATEDAO KONGYAI Department of Clinical
Microbiology Associated Medical Sciences CMU
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• less complex particle than virus
• as infectious agent
• capable to induce CPE and DISEASE

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Two Groups of Subviral pathogen
1. ??????????? - Viroid - Satellite
RNAs
2. ?????????? ???????? - Defective virus
(Satellite virus) - Prion
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VIROID

• Possess only RNA (200-400 nucleotides)
• Circular single () stranded RNA
• No capsid protein
• Autonomous replication (Host Polymerase
  enz.)
• Rolling circle
• No translation
• As infectious RNA
• High virulence (10 molecules Disease)
• ??????????? ??????????????, ???????????,
  ?????????, etc

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1. Virusoid (similar as Viroid) 2.
Differ from Viroid
- Circular single () strand RNA - Autonomous
replication rolling circle No
translation
- Linear RNA with capsid protein - have
Replication and Translation
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Defective virus (satellite virus)
Co-infect with Helper virus

• Adeno-associated virus (AAV) Adenovirus
• - RNA-dependent RNA Polymerase enz.
• Hepatitis D virus (HDV) HBV
• - capsid from HBV

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named PrP, for Prion Protein
Found in WBC and on surface of nerve cells
in the brain Normal function is Unknown
Prion ???? pathogen ????????????????????????
????? ?????????????????? (CNS)
?????????????? ??????????????????????????????
Transmissible Spongiform Ecephalopathy
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History

• 1738 First clinical manifestation of
  scrapie described. 1955 Vincent Zigas begins
  clinical study of kuru in Papua New Guinea
  1956 Dr. Carleton Gajdusek begins investigation
  of kuru Noble Prize in 19761959 WJ Hallow
  observes the similarity between kuru and scrapie.
  1962 H.B. Parry believed that scrapie can be
  eradicated by breeding methods. 1965 First
  chimpanzees injected with brain extracts of both
  kuru and CJD patients
• developed similar symptoms to the
  respective diseases.

1982 Stanley Prusiner et al develop animal
model for studying prion infectivity. 1986 BSE
epidemic in England. Believed to arise from
contaminated feed. 1988 N. Hunter observes
fibrils in BSE infected cows that are similar to
scrapie protein. 1990 J.
Hope determines two alleles of protein gene
linked to scrapie in sheep. 1991 Stanley
Prusiner elucidates the molecular biology of
prion proteins. 1993 T.G.F. Esmonde determines
possible links to CJD caused from BSE.(vCJD)
1997 Stanley Prusiner Nobel Prize for work
in Prion concept
1999 Discovery of the PrP homolog (Moore
et al.,1999) 2001 Complement involved in
prion pathogenesis ( Klein et al.,2001)
2003 Transgenic expression of soluble PrP
inhibits prion replication (Meier et al.,)
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Protein-only hypothesis

• Prion contain only of Protein
• No DNA or RNA
• 1972 Resident in neurology at UCSF
• encountered patients died
• from CJD

Stanley Prusiner published first major article
Science 216 136-144, 1982. infectious
agent for scrapie was a new kind of
pathogen that consisted mainly of protein and
lacked nucleic acid
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PRION termed by Prusiner Proteinaceous
Infectious Particles Suffix with - ON
elementary particle
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PrPC Structure

• Cellular prion protein
• 50 alpha-helix content
• 20 beta-sheet content
• Completely sensitive to proteinase-K digestion
• PrP-sen
• GPI-linked surface glycoprotein
• t 1/2 3-6 hr

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PRNP gene
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The structure of PrP

• There are 3 a-helical segments
• H1(144154), H2 (173194), H3 (200228)
• - 2 antiparallel ß-strand regions, S1 (128131),
  S2 (161164)

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PrPSC Structure

• Scrapie prion protein
• High in beta-sheet content (gt40)
• Partial resistance to proteinase K digestion
  PrP-res
• Can form aggregated fibrous or amyloid structure
• Intracellular/cell surface
• /extracellular space
• t 1/2 gt 24 hr

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PrPSC Structure

• Involves refolding two helices into beta-sheets
• Disulfide bond remains intact
• Accumulates in nervous tissues of PrD patients
  (rodent model and vCJD)
• Can recovered from lymphoreticular tissues,
  tonsil, spleen or lymph node
• Considerable about safety of blood donation

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??? Prions ????
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??? Prions ???????
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- Origin Mutation of PRNP gene
PrPc to PrPsc spontaneous conversion

- mRNA of PrPc normal PrPc and PrPsc
same amino acid (253 aa) - PrPc
PrPsc
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Generation of PrPsc from PrPc
Normal PrPc synthesis and cell turnover with
possible sites of conversion to PrPsc
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Conformational Conversion

• Theories or modes of infection for disease
• Virus mediated (slow virus) not DNA or RNA
• Protein only hypothesis
• Template directed refolding
• Third partner protein (protein X)
• Nucleation or seeding

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Conformational Conversion
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Prion Disease in Human
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• Prion Disease in Human
• Kuru
• - Papua New Guinea Brain and organ
• - CNS ???? ????????
• ??????????????????????????
• Total loss of speech
• - Died in 1 year

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• Gerstmann-Straussler-Scheinker
• (GSS) syndrome
• - Familial disease
• - Mutation of PRNP gene
• - Dementia (4.5 y)

• Fatal Familial Insomnia (FFI)
• - Familial disease
• - Mutation of PRNP gene
• - Isomnia

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• Creutzfeldt-Jakob Disease (CJD)
• - 1920 1/106/year
• Elder case (50-60 y)
• Sporadic - Most
• Familial disease - 5-10
• Iatrogenic - 1-5
• Variant 146 cases

- ???????????? ??????????????
????????????????-????? - Died in 1 year 90
- survive for 10 yr
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Differentiating vCJD sCJD
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vCJD, in the USA

• A girl lived in Florida, USA
• She was born in England (1979)
• moved to the United States in 1992.
• contracted the disease when she lived in
  England.
• November 2001, began to forget things and lose
  her temper, her hand began to shake pretty
  rapidly and stumble walking
• took to England in early 2003, where she was
  diagnosed with probable vCJD
• received experimental treatment with quinacrine
  for
• 3 months but not improve conditions
• All treatments failed, she died in June 2004
• (25 years)

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Bovine spongiform encephalopathy (BSE)

• Mad cow disease originated from scrapie
• a meat and bone meal product in animal food
  industry , epidemic began in 1986
• in 1992 ruminant protein feed, bring the epidemic
  under control, loss of nearly 200,000 diseased
  cattles
• also affected the tallow, gelatin, and
  pharmaceutical industries, all of which make
  bovine-derived products.
• By 1996, estimated 750,000 cows with BSE had
  entered the food chain in Great Britain
• Zoonotic Disease vCJD

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Establishing the LinkBetween BSE and vCJD

• Temporal / geographic association
• Macaque monkeys infected with brain from
• BSE-infected cow developed symptoms
• and pathological changes similar to vCJD
• Laboratory studies ("strain typing") show
• identical distinct molecular features
• (which differ from sCJD)

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?????????????????? Prion - Clinical
symptom - 14-3-3 protein (in CSF)
ELISA - Amyloid plaque (in lymphoid
tissue tonsil biopsy) - Spongiform
encephalopathy with gliosis - Inoculate
into animal
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Amyloid Plaques

• BSE, CJD, and Alzheimer's Disease show numerous
  amyloid plaques that cause spongiform
  degeneration.

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??????????? Prion - No effective
drug - No effective vaccine -
Polyanions delay the progression of Dz.
- Amphoteracins (?????????????)
inh. of PrPsc accumulation -
Quinacrine (??????????????????) delay the
progression of Dz.
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• ?????????????
• ?????????????
• - universal precaution
• - ???????? 1 N NaOH 5-10 ????
• ??????????
• 5 sodium hypocholite
• Autoclave 121oC (90 min), 132 oC (60-90 min)

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Thank you