Have you ever heard of prions <pree-ons>? Well, even if you haven't, you've probably heard about the "Mad Cow Disease" outbreak that occurred in England a few years ago. Mad Cow Disease, or bovine spongiform encephalopathy <boh-vine sponge-ee-form en-sef-uh-lah-pah-thee> (BSE) as it's scientifically called, is a deadly illness of cattle's central nervous system. Small holes develop in the animals' brains, making them eventually look like big, hole-riddled sponges. Dozens of people in England are thought to have gotten a human form of BSE by eating the meat of infected cattle. The human illness is called new variant Creutzfeldt-Jakob <croits-feld ya-cob> Disease, or nvCJD.
The most interesting thing about these terrible brain diseases is that no one has been able to find for sure the infectious agent—that is, the virus or bacterium or fungus or parasite—that's the cause.
An unusual theory has been suggested that a new kind of infectious agent, a misshapen protein—aka, a prion—is responsible for these brain diseases. This is a radical idea because it seems almost impossible that something without any genes could cause infections. Proteins contain no genes—rather they are what genes code for, the products of genes.
So what exactly are prions? And how could they cause disease? What proof is there that they even exist and who dreamed up this prion theory anyway? All these questions are addressed in this article on prions:
The Mysteries of Mad Cow Disease: Hunting the Elusive Prion
You'll find some good links in this article to the latest news on the human death toll from nvCJD and to the paper that first proposed the existence of prions.
Now, not all scientists accept the idea that prions exist or cause the brain ailments. Several still believe that an unknown, really slow-acting virus is responsible for BSE and nvCJD. Who's right? We just don't know for sure yet. Science doesn't always yield quick discoveries, especially on such difficult problems. The prion theory is still that: a theory, or a guess with some evidence to support it. At the same time, the idea that slow-acting viruses cause these diseases is just a theory, too.
Here are some more links about prions:
Also, can prions be all bad? While it's not certain that prions cause brain diseases, a number of researchers do think that prions exist. But why? Check out this article that describes research into one useful role prions might normally serve in the body.
Deadly 'Mad Cow' Protein May Help Nerve Cells Work
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