Prion Infections

• CJD

  • Most common prion disease in humans; typically seen in older people

  • Starts with subtle behavior changes followed by rapid progressive dementia (most rapidly progressive of human prion diseases – uniformly fatal within a year of c/s onset)

  • Startle myoclonus is common in later stages

  • Transmitted by exposure to eye and neural tissue products, but there are familial and sporadic forms

• vCJD (new vCJD)

  • Seen in younger patients

  • Associated with consumption of BSE beef

  • More protracted than is classic CJD

• Kuru – cannibals in Papua/New Guinea

• Scrapie

• Mink encephalopathy

• BSE

• Gerstmann-Straussler-Schenker syndrome – presents with progressive ataxia

• Familial fatal insomnia – characterized by sleep disturbances leading to dementia

• Kuru plaques can be seen in all of the prion diseases (these are amyloid plaques)

• Pathogenesis of prion diseases in general

  • Prion protein (PrP) is a normal protein that we all make

  • Some folks have a PrP that is prone to change from its alpha helix to a beta pleated sheet; when this happens, it encourages other PrP around it to change conformation as well (now called PrP_SC)…lots of PrP_SC cause spongiform changes – this explains how prion disease can be acquired and spontaneous

  • If you don’t make PrP you are immune from prion diseases

  • PrP_SC is very resistant to proteases, heat, and steam (autoclaving)

Category: Pathology Notes