General Background on Prions

1. General Background on Prions

2. Introduction to Prions • Pronounced “pree-on” • Shortened term for: Proteinaceous Infections Particle

3. Introduction to Prions • Pronounced “pree-on” • Shortened term for: Proteinaceous Infections Particle • Causes TSE (Transmissible Spongiform Disease) which attacks the central nervous system (the brain).

4. Discovery • Study started in 1967 by British scientist, Tikvah Alper, at Hammersmith Hospital in London.

5. Discovery • Study started in 1967 by British scientist, Tikvah Alper, at Hammersmith Hospital in London. • Discovered by American neurologist, Stanley B. Prusiner, in 1982.

6. Basic Structure • Normal prions contain about 200-250 amino acids twisted into three telephone chord-like coils known as helices, with tails of more amino acids.

7. Basic Structure • Normal prions contain about 200-250 amino acids twisted into three telephone chord-like coils known as helices, with tails of more amino acids. • The mutated, and infectious, form is built from the same amino acids but take a different shape. Normal Mutated

8. Basic Structure • Normal prions contain about 200-250 amino acids twisted into three telephone chord-like coils known as helices, with tails of more amino acids. • The mutated, and infectious, form is built from the same amino acids but take a different shape. • 100 times smaller than the smallest known virus. Normal Mutated

9. Basic Structure Normal Mutated

10. Differences From Bactera & Viruses • Prions do not contain nucleic acid; they don’t have DNA or RNA.

11. Differences From Bactera & Viruses • Prions do not contain nucleic acid; they don’t have DNA or RNA. • They are extremely resistant to heat and chemicals.

12. Differences From Bactera & Viruses • Prions do not contain nucleic acid; they don’t have DNA or RNA. • They are extremely resistant to heat and chemicals. • Prions are very difficult to decompose biologically; they survive in soil for many years.

13. Prion Diseases • Humans: CJD (Creutzfeldt Jakob Disease) GSS (Gerstmann Straussler Syndrome)

14. Prion Diseases • Humans: CJD (Creutzfeldt Jakob Disease) GSS (Gerstmann Straussler Syndrome) • Cattle: BSE (Bovine Spongiform Encephalopathy, better known as Mad Cow Disease)

15. Prion Diseases • Humans: CJD (Creutzfeldt Jakob Disease) GSS (Gerstmann Straussler Syndrome) • Cattle: BSE (Bovine Spongiform Encephalopathy, better known as Mad Cow Disease) • Sheep: Scrapie • Deer/Elk: CDW (Chronic Wasting Disease)

16. Controversy • DNA and RNA are the only substances now known to replicate in body tissues, so how do prions make copies of themselves without any nucleic acids?

17. Controversy • DNA and RNA are the only substances now known to replicate in body tissues, so how do prions make copies of themselves without any nucleic acids? • Some believe TSEs are caused by an unidentified slow-acting virus. • Others believe a small virus accompanies a prion and they work together to cause disease.

18. Any questions?

19. Thank you.