WHAT DO WE KNOW ABOUT PRIONS?

Prions are infectious agents made primarily of a misfolded host protein rather than nucleic acid, and they cause a distinctive group of fatal neurodegenerative diseases in humans and animals. Over four decades of research has established the core “protein-only” concept: a normal cellular prion protein can adopt an abnormal conformation that templates further misfolding, accumulates in the nervous system, and produces progressive brain damage after long incubation periods. What makes prions scientifically and practically important is not only their clinical severity but also their unusual biology: they can exist as different “strains” encoded by conformation, show strong species barriers, persist in the environment, and resist many routine decontamination methods.