What defines prions in biological terms?

Prions are defined in biological terms as infectious pieces of protein. Unlike viruses or bacteria that contain nucleic acids (DNA or RNA), prions are unique in that they lack any genetic material. Instead, they are misfolded proteins that can induce other normally folded proteins in the brain to also misfold, leading to severe neurodegenerative diseases. This misfolding disrupts normal cellular function and causes a cascade of further protein misfolding, resulting in brain damage.

The nature of prions as proteins makes them particularly interesting and concerning in the study of infectious diseases. In contrast to infectious agents that replicate through nucleic acids, prions spread their pathological effects through protein conformational changes, illustrating a different mechanism of infection and disease propagation.