Lecture%2012

Lecture%2012 - Prions and Transmissible Spongiform...

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Prions and Transmissible Spongiform Encephalopathy
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Prions and Transmissible Spongiform Encephalopathy The prion hypothesis A. The diseases in question - Developed to explain transmission of several very similar diseases of the brain: some genetic and some transmissible - Disease is progressive and fatal, begins with symptoms: brain dysfunction (ataxia, confusion), ends with coma and death
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Some described several decades ago Others appeared recently Genetic: occur late in life Transmissible explained by exceedingly long incubation periods
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Human Creutzfedlt-Jakob disease (CJD) 1 Gerstmann-Straussler- Scheinker disease (GSS) 1 Fatal familial insomnia (FFI) 1 Kuru disease 2 Animal Scrapie in sheep 3 Chronic wasting disease (CWD) in mule deer and elk 4 Transmissible mink encephalopathy 4 Bovine spongiform encephalopathy 4 Feline spongiform encephalopathy 4 1.Thought to be genetic 2.Presumed transmitted through consumption of human brains 3.Possibly genetic and transmissible features 4.Throught to be transmitted through consumption of neural tissue from scrapie sheep or BSE cattle
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Pure protein replicative particles The basic idea 1980, Stanley Prusiner at UCSF: hypothesis that the disease agent was a pure protein, could direct the formation of more protein like itself by serving as a template for folding “PRION” pro teinaceous in fectious particle Normal proteins of animal tissues can misfold and become infectious
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How it works Conformational change normal neural protein PrPc (for the cellular form of the prion protein) Change induced by contact with an aberrant conformation of same protein called PrPsc (for scrapie form of same protein) Net result of physical interaction of PrPc with PrPSc PrPc converted into PrPSc form Cause same conversion in any other PrPc proteins which it comes in contact with
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The presence of the PrPSc culprit due to a) Introduction of foreign PrPSc particle from food b) Spontaneous (but very rare) event
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Lecture%2012 - Prions and Transmissible Spongiform...

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