any of several types of protein particle lacking nucleic acid, believed to be the cause of certain slow-developing infectious diseases such as scapie in sheep, and Creutzfeldt-Jakob disease and Kuru in humans.

A protein particle thought to be the agent responsible for BSE

A small protein found in the brain cell membrane. The distorted form of this protein is responsible for the mad cow disease and causes new Creutzfeld-Jakob disease in humans.

Putative infectious protein that is associated with spongiform encephalopathies such as scrapie, BSE and Creutzfeldt Jakob disease.