The causative agent of mad-cow disease:

$\mathrm{M}$ a d c o w d ise a se, or bovine spongiform encephalopathy (BSE), is a disease that was first found in cattle is caused by a prion. Related Theory Prions are the infectious agents responsible for several neurodegenerative diseases in mammals. This happens due to the abnormal folding of the proteins in the brain. It refers to the hypothesis that the infectious agents causing the diseases contain only proteins. It explained why the infectious agents are resistant to ultraviolet radiations. They can break down the nucleic acids, but are receptive to substances that denature proteins.