PRIONS

Prion Diseases aka Transmissible Spongiform Encephalopathies are caused due to accumulation of abnormal infectious proteins

·         Prions are the only infectious pathogens which are devoid of nucleic acid.

·         Prion diseases etiology -infectious, genetic, and sporadic disorders.

·         Prion diseases occur due to accumulation of PrP^Sc (commonly, β-pleated) instead of the normal precursor, PrP^C (α-helix).

·         PrP^Sc can induce a change in normal configuration of PrP^C, so that it also converts to PrP^Sc.

·         Prion proteins are resistant to most of the disinfectants. To sterilize Prion proteins:-

o   Autoclaving at 134°C for 5 h or

o   Treatment with 2 N NaOH for several hours

o   (CJD Prions bound to stainless steel surfaces are resistant to inactivation by autoclaving at 134°C for 2 h. Susceptibility can be induced by exposing bound prions to an acidic detergent solution prior to autoclaving.)

·         EEG features- Repetitive, high-voltage, triphasic, and polyphasic sharp discharges/periodic bursts of <200 ms duration, occurring every 1–2 s.

Important Prion Diseases:-

Humans-

1.       Creutzfeldt-Jakob disease

2.       Fatal Familial Insomnia

3.       Gerstmann-Sträussler-Scheinker disease

4.       Kuru Disease

Sheep/goats-

1.       Scrapie

Cattle-

1.       Bovine Spongiform Encephalopathy

Cats-

1.       Feline Spongiform Encephalopathy