Prions: The Newest Disease Agents

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Transmissible Spongiform Encephalopathy (TSE)

• TSE is a group of diseases caused by prions.• A prion is a disease-causing protein.• Common types of TSE:

– “Mad Cow Disease” (BSE)– Scrapie– Kuru– Creutzfeldt-Jakob disease

How Prions Cause disease• This is a

normal protein in your brain.

• It has important functions your brain needs

Same Protein, 2 Shapes

NormalProtein

DiseaseProtein(prion)

When Good Proteins Go Bad• The prion changes the shape of the normal protein,

making it defective and infectious.

So What About the Cow?

Brain tissue of infected cow: spongiform

Transmission: Cannibalism

• Prions that cause disease are eaten, and then begin transforming proteins in the new victim.

• Mad cow disease can be transmitted to humans (200+ known cases)

• So how did cows get prions from other cows?

Rendering Factories

• Industrial animal production feeds animals the remains of dead animals.

“Downer” cattle: now outlawed as feed

Mmmm… Uncle Larry!

The Meatrix• Industrial food production (CAFOs) have had major

effects on human health, as demonstrated in this unit:– H1N1 influenza– BSE

• Other implications we have not considered that affect humans:– Pollution (12,000,000 tons of animal waste/day)– Antibiotic resistance (70% of all antibiotics fed to

animals)– Animal welfare

But Before We DoDisease Agent /

OrganismKey characteristics

Bubonic Plague Yersinia pestis Killed 40% of human population. Gram – bacteria. c.1350

Influenza H1N1 Influenza virus New strain contains swine, avian, and human genes. Normal viral life cycle

AIDS HIV Retrovirus which inserts viral genes into host DNA.

Tuberculosis Mycobacterium tuberculosis

Infects lungs. Kills 2 million yearly. Some strains are antibiotic resistant

Anthrax Bacillus anthracis Spore forming Gram + bacteria. Easily weaponized, responisible for 2001 anthrax attacks

Mad Cow Disease / TSEs

Prion proteins Prion disease which targets brain tissue.