What is a prion?

A prion is defined as a proteinaceous infectious particle, which means it is an abnormal form of a protein that can induce misfolding in normal proteins within the brain and other tissues. This misfolding process disrupts normal cellular functions and leads to a range of neurodegenerative diseases, such as Creutzfeldt-Jakob disease and mad cow disease, among others. Unlike traditional infectious agents such as viruses, bacteria, or fungi, prions lack nucleic acids (DNA or RNA) and do not replicate in the conventional sense; instead, they propagate by converting normal proteins into the abnormal prion form.

The distinction of prions from viruses, microorganisms, and bacterial agents is crucial, as it emphasizes their unique infectious mechanism and pathogenesis, which is distinct from conventional pathogens typically studied in microbiology and infectious disease.