Prions are infectious agents those are composed primarily of proteins. To date, all such agents that have been discovered propagate by transmitting a misfolded protein state. Prions are proteins that are unique in their ability to reproduce on their own and become infectious. The protein itself does not self-replicate and the process is dependent on the presence of the polypeptide in the host organism. The misfolded form of the prions proteins have been implicated in a number of diseases in a variety of mammals.