Every few years, a case of Mad Cow Disease will appear somewhere in the world and cause panic. This past April, a cow in California tested positive for the disease. The California Department of Agriculture assures us that the case was caught well before it made its way into the food supply and that it was an isolated case, but you still have to wonder where the disease came from, and if there are some undiagnosed cows out there.
Why is the threat of Mad Cow so scary? Mad Cow Disease, also called Bovine Spongiform Encephalopathy (BSE), is a prion disease. And when humans eat infected meat, they can develop a prion disease called Creutzfeldt-Jakob disease (CJD), a fatal, untreatable neurodegenerative illness.
Prions are very simple: just normal proteins that are found in your brain. But things go wrong when prions start to misfold, changing their shape so they stop being a useful, functional protein and instead become pathogenic killers that tear apart your brain and ultimately kill you. In this episode, we talk about how prions work, why they occur, and how to avoid getting the disease.
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Here’s a portion of a normal, non-pathogenic prion protein. Notice that it is made mostly of alpha helices.
And here’s the misfolded, pathogenic prion protein. Notice that it is mostly made of beta sheets. Once misfolded, the protein aggregates with others to form long amyloids. Here, five misfolded prion proteins have joined together to form the long, destructive amyloid.