<prompt> True about prions are all except: September 2009Associated with Cruetzfeldt-Jacob diseaseHeat labileSensitive to proteasesInfectious proteinaceous paicles  <response>: Ans. B: Heat labile Prions are unconventional virus like agent. Prions are transmissible paicles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein. They are resistant to heat 90 degree C for 3 minutes, UV rays and nucleases and sensitive to proteases. Prion diseases may present as genetic, infectious, or sporadic disorders, all of which involve modification of the prion protein PrP. Bovine spongiform encephalopathy BSE, scrapie of sheep, and Creutzfeldt-Jakob disease CJD of humans are among the most notable prion diseases. 