Course: Virology
Lecturer: Dr. Weam SaadLecture: Prions and Oncoviruses
Structure and Pathogenesis:
Prions are not viruses they are protein infectious neurodegenerative particles associated with transmissible spongiform encephalopathies (TSE) of both humans and animals. Prions are misfolded transmissible proteins which associated with several fatal neurological diseases in animals and humans due to accumulation of prion protein leading to tissue damage and cell death (cels of the central and peripheral nerves). The mechanism of misfolding of the normal protein is not known. Human prion is called PrPSc. The word prion derives from "proteinaceousinfectious particle".
All known prion diseases inmammals affect the structure of the brain and other neural tissue; there is no known effective treatment and these infected cases are always leaded to death.
Prion proteins have stable structures and resistant to denaturation by chemical and physical agents. And that make the decontamination difficult (cannot be destroyed by boiling, alcohol, acid, standard autoclaving methods, or radiation). They usually spread to humans by ingestion of infected meat products.
The Most common cases of TSEs include bovine spongiform encephalopathy (BSE) in cattle (known as "mad cow disease" or cow madness disease), and Creutzfeldt-Jakob disease (CJD) in humans. Bovine spongiform encephalopathy called spongiform because the brain develop large vacuoles in the cortex and cerebellum regions), then paralysis occur and death.
(Prions chemical structure)