Prions

Question 1

The protein only hypothesis

Answer 1

prion diseases occur from the conformational change (protein misfolding) from a normally functioning prion protein (PrPc) to a protease resistant form (PrPsc)

Question 2

What proves protein only hypothesis

Answer 2

1. No virus, bacteria or fungi associated with prion disease
2. No nucleic acid associated with infectivity
3. No immune response to infection

Question 3

Self replication

Answer 3

1. Nucleation between two PrPsc
2. this nucleus recruits other PrPc and converts them to PrPsc
3. this nucleus increases in size
4. Fragmentation (liberates new ends and disseminates infections material)

Question 4

Differences between vCJD and sCJD

Answer 4

• type 4 PrPsc in vCJD (1-3 in sCJD)
• vCJD can be transmitted person to person through blood transfusion or ingestion of food contaminated with BSE
• vCJD younger onset ( 29 yrs v. 65 yrs)
• vCJD has less rapid progression (14 v. 5 months)
• vCJD has peripheral pathogenesis especially lymphoreticular tissue
• vCJD has plaque consisting of round amyloid core surrounded by ring of spongiform

Question 5

Similarities between vCJD and sCJD

Answer 5

• Sporadic with no known cause
• similar clinical presentation(rapid mental deterioration and myoclonus)
• both fatal
• use brain biopsy to diagnose
• Both use MRI and have abnormal results but the results are distinctly different