A prion is a protein of unknown function that resides on the surface of brain cells. Sidney Perkowitz
especially: an abnormal form of prion protein that in mammals includes pathogenic forms which arise sporadically, as a result of genetic mutation, or by transmission (as by ingestion of infected tissue) and which upon accumulation in the brain cause a prion disease (such as bovine spongiform encephalopathy or Creutzfeldt-Jakob disease)
Abnormal proteins, known as prions, may trigger mad-cow disease simply by coming into contact with healthy proteins in the brain. Time
… the infectious prion conformation replicates itself in a host by catching the 'benign' host prion protein and forcing it into the infectious conformation. Roland Riek
Word History
Etymology
Noun (1)
New Latin, from Greek priōn saw, from priein to saw; from its sawlike bill