Prions

1. Prions Sly Richards

2. History • The first cases of transmissible spongiform encephalopathies were reported in Great Britain in the 1700’s. • The first case was documented in sheep and is called Scrapie. • In the 1970’s, the prion disease was widely recognized in Papua New Guinea and was called Kuru.

3. Back ground Information • A prion is an infectious agent in the form of a misfolded protein. • Prions are different compared to other infectious agents. • They have no genetic material and they are smaller than viruses. • They are not alive. • Prions are responsible for neurodegenerative spongiform encephalopathies. • 10% of prion diseases are hereditary and the other 90% are contracted or sporadic. • Prion disease is contracted by consuming contaminated meat. • All prion diseases are neurodegenerative and lethal. • All prion diseases have an incubation period but it can range from weeks to years depending on the spread rate of the prions.

4. Infection • In every organism, there is a protein in the body that scientists believe prions originate from. This protein can misfold and become a prion. • When a prion enters a healthy organism, it travels to the brain where the preexisting prion proteins reside and when it touches one of them, that protein becomes a prion, and a chain reaction occurs.

5. Transmission • There are three different ways that a species can contract prions: acquired, inherited, or sporadic. • The primary transmission method in animals is acquired by ingestion. When an animal dies of a prion disease, other animals can eat it or prions can linger on particles of dirt. If it is in a nearby water source it could contaminate that. • Infection can occur from manure and since manure can be near reservoir areas it can leak into the water supply and contaminate it. • Prions can also bind to airborne particles and travel large distances.

6. Sterilization • Sterilization of prions is extremely difficult because of their extremely stable structure. • Prions are resistant to all normal methods of sterilization. • Effective sterilization relies upon protein hydrolysis, reduction, or destruction of the protein tertiary structure. • Bleach, caustic soda, or strong acidic detergents can be used to destroy prions.

7. PrPc • PrPc is a normal protein found throughout the body. • PrPscis the infectious form of the protein • When it touches the normal protein, the normal protein transforms into the infectious protein which starts a chain reaction. • A group of prions starts forming which causes the neuro-degeneration and eventual death.

9. Species

10. Scrapie • The name scrapie come from one of the symptoms of the disease. Animals will compulsively scrape against anything they can find which causes rashes and bare spots on the fleece. • Other symptoms are excessive smacking of lips, strange walking patterns, and convulsive collapsing.

12. Mad Cow Disease • When a prion infects cattle, it will cause a change in behavior, uncoordinated movements, trouble standing and walking, weight loss despite an appetite, and decreased milk production. • Eventually the cow dies. • In Europe, there used to be a program called MBM which stood for meat and bone meal. • European farmers used to feed cattle the ground up remains of other cattle • some of those would be infected and that was how an epizootic occurred.

15. Transmissible Mink Encephalopathy • TME is a rare disease that affects only adult mink and usually only occurs in ranch-raised mink. • The symptoms of this disease are behavioral changes, loss of cleanliness, aimless circling, weight loss, matted fur, hind quarter ataxia, and seizures rarely occur.

16. Chronic Wasting Disease • This causes cervids (the deer family) to slowly lose weight and eventually die. • The symptoms include decreased interactions with other animals, listlessness, lowering of the head, blank facial expression, repetitive walking in set patterns, and a smell like rotten flesh.

17. Feline Spongiform Encephalopathy • This disease effects the brains and liver of cats. It symptoms include behavioral changes and ataxia.

18. Exotic Ungulate Spongiform Encephalopathy • This affects exotic zoo animals. This prion infectious disease was spread when these animals were fed supplemented meat and bone meal.

19. Spongiform Encephalopathy • Ostrich can contract this disease, but once they contract it, it has been theorized that the disease is not transmissible.

20. Creutzfeldt-Jakob Disease • This form of prion disease affects humans. • Symptoms • Dementia followed by memory loss, personality changes, hallucinations, speech impairment, jerky movements, balance and coordination dysfunction, changes in gait, rigid posture, and seizures.

22. Kuru • Kuru is a Prion disease that was noticed in Papua new Guinea. • It was transferred throughout the tribe via cannibalism. • Classic symptoms involved tremorsand sporadic laughing.