What Are Prions? The Mysterious Proteins That Defy Biology

If you’ve ever heard of "mad cow disease" or CreutzfeldtJakob disease (CJD), you’ve already encountered prions—some of the most bizarre and deadly infectious agents known to science. Unlike bacteria, viruses, or fungi, prions aren’t alive. Yet, they can cause fatal brain diseases by doing something truly strange: misfolding proteins and turning them into infectious zombies.

In this article, we’ll break down:

✔ What prions really are

✔ How they cause disease

✔ Why they’re nearly indestructible

✔ The scary diseases linked to them

✔ Whether prion infections can be treated

Let’s dive in!

What Exactly Are Prions?

Prions (pronounced preeons) are misfolded proteins that can trigger normal proteins in the brain to misfold as well. The word "prion" comes from proteinaceous infectious particle—basically, an infectious protein.

Key Facts About Prions:

They’re not alive—no DNA, no RNA, just a rogue protein.

They’re incredibly tough—resistant to heat, radiation, and disinfectants.

They cause brain damage by forming clumps that destroy nerve cells.

Unlike typical infections, your immune system doesn’t recognize prions as a threat, making them even more dangerous.

How Do Prions Cause Disease?

Prions are notorious for causing fatal neurodegenerative diseases in humans and animals by corrupting normal proteins in the brain.

Imagine a single misshapen Lego block forcing all the normal Legos around it to bend out of shape. That’s essentially what prions do:

1. A normal brain protein called PrP (prion protein) gets twisted into a harmful shape.

2. This misfolded prion bumps into healthy PrP proteins, forcing them to misfold too.

3. The misfolded proteins clump together, forming plaques that kill brain cells.

4. Over time, this leads to spongiform encephalopathy—a condition where the brain develops holes, resembling a sponge.

Diseases Caused by Prions

Prion diseases (also called transmissible spongiform encephalopathies) are rare but always fatal. Some affect humans, while others target animals.

Human Prion Diseases:

CreutzfeldtJakob Disease (CJD) – Rapidly progressive dementia, usually sporadic but can be inherited or transmitted.

Variant CJD (vCJD) – Linked to eating beef from cows with mad cow disease (BSE).

Fatal Familial Insomnia (FFI) – A genetic prion disease causing severe insomnia and neurological decline.

Kuru – Once spread among the Fore people of Papua New Guinea through ritualistic cannibalism.

Animal Prion Diseases:

Bovine Spongiform Encephalopathy (BSE, "mad cow disease") – Spread through contaminated feed.

Chronic Wasting Disease (CWD) – Affects deer, elk, and moose; raises concerns about transmission to humans.

Scrapie – Found in sheep and goats for centuries.

Why Are Prions So Hard to Destroy?

Prions are scary resilient. Here’s why:

✔ Heat resistant – Normal cooking or pasteurization doesn’t kill them.

✔ Chemical resistant – Alcohol, formaldehyde, and UV light don’t work.

✔ Protease resistant – Enzymes that break down normal proteins can’t destroy prions.

Hospitals use extreme measures like incineration or strong bleach solutions to sterilize prion contaminated tools.

Can Prion Diseases Be Treated or Prevented?

Currently, no cure exists for prion diseases. Once symptoms appear, the condition is always fatal, usually within months to a few years. However, researchers are exploring:

Antibodies that target misfolded prions.

Drugs that stabilize normal PrP proteins.

Gene therapy to prevent prion formation.

What Makes Prions So Dangerous?

No Cure or Treatment – Always fatal once symptoms appear.

Resistant to Destruction – Survive cooking, UV light, and standard sterilization.

Long Incubation Periods – Symptoms may take years to decades to appear.

Risks of Transmission

Eating Infected Meat (BSE → vCJD in humans, CWD in deer).

Medical Procedures (Contaminated surgical tools, corneal transplants).

Genetic Mutations (Familial prion diseases like FFI).

Prevention Tips:

Avoid eating nervous system tissue from infected animals.

Follow strict medical sterilization protocols.

Genetic counseling for families with inherited prion diseases.

Can Plants or Non-Mammals Be Affected?

No evidence that prions infect plants, insects, birds, or reptiles.

Only mammals are known to develop prion diseases.

Final Thoughts: The Unsettling Mystery of Prions

Prions target the brain and nervous system of mammals, causing irreversible damage. While rare, their 100% fatality rate and resistance to destruction make them a significant concern in medicine, agriculture, and food safety. Prions challenge everything we know about infectious agents. They’re not alive, yet they spread. They’re simple, yet they cause devastating diseases. While rare, prion disorders remind us how much we still have to learn about the brain and infectious diseases.

CDC - Prion Diseases
https://www.cdc.gov/prions/index.htm

CDC - Bovine Spongiform Encephalopathy (BSE / Mad Cow Disease)
https://www.cdc.gov/prions/bse/index.html

WHO - Prion Diseases Fact Sheet
https://www.who.int/news-room/fact-sheets/detail/prion-diseases

NIH - Creutzfeldt-Jakob Disease (CJD) Information
https://www.ninds.nih.gov/health-information/disorders/creutzfeldt-jakob-disease

PubMed Central - Prion Research Articles
https://www.ncbi.nlm.nih.gov/pmc/?term=prions