(n) (microbiology) an infectious protein particle similar to a virus but lacking nucleic acid; thought to be the agent responsible for scrapie and other degenerative diseases of the nervous system
n. 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. [ informal ] [ PJC ]