Prions are scary, really scary. They are the responsible agent for Creutzfeld Jakob's disease and Mad Cow Disease. Shawna and I were finishing a quiz for Biochem and one of the questions asked about prions, so we did a little research that freaked me out.
Almost without exception, infectious diseases come from viruses, bacteria, fungi, something with genetic material to reproduce itself. And for the most part, life has come up with defense mechanisms against these agents. Prions are different.
So, a bit of background. Proteins are pretty important. They make up most of our body. They are catalytic proteins (enzymes), signaling proteins (hormones), structural proteins, and more. DNA codes for proteins. Proteins are sequences of amino acids. Some proteins are long, some short. But longer ones fold into characteristic shapes, or conformations, based on the sequence of amino acids and their properties. Some amino acids attract each other, others repel, some are hydrophobic, some hydrophilic. The shape or conformation of a protein is crucial to its purpose. Basically, shapes are really important on a molecular level. Our body is kinda like a complex baby's toy where you fit the right block and right whole. Proteins can lose their shape because of pH or heat or other agents. In fact, when you cook eggs, the change is the denaturation of the proteins, or the proteins losing their fold. When you cook meat, you guessed it, also denaturation.
Okay, enough background. In the case of Creutzfeldt-Jakob disease and other prion diseases, there is a protein that is normally found in your body called PrP. Its purpose is not known, but it may be useful in memory. Then comes along a prion. This prion is also a protein. In fact it is the same sequence of amino acids as PrP, so sequentially it is identical. But remember how shape is a pretty big deal to proteins? Well, this prion is the same protein, misfolded. And this misfolded prion interacts with folded PrPs and gets them to misfold too. And now those get more to misfold. This wouldn't be too big of a deal, except for the fact that these proteins, now misfolded, create a new structure in your body. They fit together like legos to form what are called beta sheets, specifically in this case amyloid folds. These structures form in your brain and keep growing as more and more prions are induced. These aggregations of prions are especially compact and stable and form ever-growing scars in your brain. Then you go crazy. And die. Always.
There is no cure. There is no treatment. You can't kill them, because they are not alive. UV light does nothing (it usually kills stuff by mutating the DNA) because they have no genetic material. It can't be broken down by your bodies proteases (enzymes that break down proteins). In fact, it is very hard to denature or unfold them as well.
So... yeah. Prions...