What is an example of a prion pathogen?

Prions are unique infectious agents that differ from traditional pathogens such as bacteria and viruses. They are misfolded proteins that can induce other normal proteins in the brain to misfold, leading to neurodegenerative diseases. Creutzfeldt-Jakob disease (CJD) is a well-known example of a prion disease, which affects the brain and is characterized by rapidly progressive dementia, muscle stiffness, and other neurological symptoms. The infectious nature of prions and their resistance to conventional sterilization methods highlight their unique and dangerous nature compared to other pathogens.

The other options listed represent different classes of pathogens: the common cold is caused by a virus, Streptococcus pneumoniae is a bacterium responsible for pneumonia and other infections, and West Nile virus is also a vector-borne virus associated with encephalitis. None of these involve the distinct mechanism of action associated with prions, which is specifically related to misfolded proteins leading to disease.