Prions are atypical infectious agents that consist solely of protein, lacking any genetic material such as DNA or RNA. They are responsible for causing several fatal neurodegenerative diseases in humans and animals, including Creutzfeldt-Jakob disease, mad cow disease (bovine spongiform encephalopathy), and scrapie.
The term "prion" is derived from "proteinaceous infectious particle," highlighting their unique composition. These misfolded proteins can exist in two forms: a normal, harmless conformation called cellular prion protein (PrP^{C}), and a misfolded, pathogenic form known as scrapie-associated prion protein (PrP^{Sc}). The conversion from PrP^{C} to PrP^{Sc} occurs when the misfolded prions come into contact with the normal protein, inducing a change in its conformation.
Prions are highly resistant to conventional sterilization methods and are capable of accumulating and spreading within the nervous system. They can gradually destroy brain tissue, leading to a variety of neurological symptoms such as dementia, impaired motor function, and behavioral changes. These diseases typically have a long incubation period and are invariably fatal.
Prions have the ability to propagate and self-replicate without the need for DNA or RNA, using a unique mechanism that involves the induction of normal proteins to adopt the abnormal confirmation. This process leads to the formation of aggregates or plaques in the brain, further contributing to neuronal damage.
Understanding prions and their transmission mechanisms is essential for developing effective diagnostics, preventative measures, and potential treatments for these devastating diseases.
