General Background on Prions

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General Background on Prions
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Introduction to Prions

• Pronounced pree-on
• Shortened term for
• Proteinaceous Infections Particle

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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).

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Discovery

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

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Discovery

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

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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.

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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
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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
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Basic Structure
Normal
Mutated
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Differences From Bactera Viruses

• Prions do not contain nucleic acid they dont
  have DNA or RNA.

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Differences From Bactera Viruses

• Prions do not contain nucleic acid they dont
  have DNA or RNA.
• They are extremely resistant to heat and
  chemicals.

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Differences From Bactera Viruses

• Prions do not contain nucleic acid they dont
  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.

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Prion Diseases

• Humans
• CJD (Creutzfeldt Jakob Disease)
• GSS (Gerstmann Straussler Syndrome)

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Prion Diseases

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

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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)

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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?

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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.

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Any questions?
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Thank you.