What are infectious proteins called?

Infectious proteins are known as prions. Prions are unique in that they are misfolded proteins that can induce other normal proteins in the brain to misfold as well, leading to a series of neurodegenerative diseases. Unlike viruses or bacteria, which are composed of nucleic acids and can carry genetic material, prions do not contain DNA or RNA. This characteristic contributes to their ability to propagate and cause disease solely through protein-to-protein interaction, showcasing a fundamentally different mechanism of infection compared to traditional pathogens.

Viruses, while they also cause disease, are composed of genetic material (either DNA or RNA) surrounded by a protein coat and require a host cell to replicate. Viroids are another form of infectious agent, consisting of a short strand of circular RNA without a protein coat, and primarily affect plants. Bacteria are single-celled organisms that possess both DNA and cellular structures but are not classified as infectious proteins. Thus, the definition of prions fittingly describes the category of infectious proteins.