Prion diseases can affect both humans and animals and are sometimes transmitted to humans by infected meat products. Proteins Behind Mad-Cow Disease Also Help Brain Develop. Infectious prions, like those that cause mad cow disease, are misfolded versions of the prion protein. Each disease also has a particular genetic profile of the prion protein gene. So how do they work? Source. Prion diseases comprise several conditions. Prion diseases can affect both humans and animals and are sometimes spread to humans by infected meat products. However, the prion protein found in infectious material has a different structure and is resistant to proteases, the enzymes in the body that can normally break down proteins. There is also a variant form of CJD, denoted vCJD, which was first described in 1996 in the United Kingdom in connection with mad cow disease 5. Protein molecule. BSE (bovine spongiform encephalopathy) is a progressive neurological disorder of cattle that results from infection by an unusual transmissible agent called a prion. The most common form of prion disease that affects humans is Creutzfeldt-Jakob disease (CJD). Tests have shown the "bad" prions fold in a certain shape and somehow transmit this to healthy prions. Prions are proteins found in the brain, which have been recently linked with bovine spongiform encephalopathy (BSE or mad cow disease) and relatives like CJD. Prion diseases are caused by propagation of misfolded forms of the normal cellular prion protein PrP C, such as PrP BSE in bovine spongiform encephalopathy (BSE) in cattle and PrP CJD in Creutzfeldt-Jakob disease (CJD) in humans 1.Disruption of PrP C expression in mice, a species that does not naturally contract prion diseases, results in no apparent developmental abnormalities 2 – 5. Infectious prions spread the misfolding to their normal counterpart proteins. The identification of a new variant of Creutzfeldt–Jakob disease, and its interpretation as evidence of transmission of mad cow disease to man, rely critically on our understanding of the epidemiology of prion diseases. Another example of an acquired human prion disease is kuru, which was identified in the South Fore population in Papua New Guinea. Like other prion diseases, there is no known cure 28. The nature of the transmissible agent is not well understood. The protein that prions are made of is found throughout the body, even in healthy people and animals. These diseases are intimately associated with conformational conversion of the cellular prion protein, PrP C, into an oligomeric β-sheet rich form, PrP Sc. In cows, this form of the disease is known as bovine spongiform encephalopathy (BSE) or, more commonly, "mad cow disease."