Final answer:
Stanley Prusiner discovered prions in 1982, identifying them as infectious proteins without DNA or RNA and responsible for several neurodegenerative diseases. He was awarded the Nobel Prize for this work in 1997. Prions propagate by causing normal prion proteins to misfold into a disease-causing form.
Step-by-step explanation:
In 1982, Stanley Prusiner made a groundbreaking discovery in the field of infectious diseases. He found that certain diseases were caused by proteins that were capable of transmitting infection without containing DNA or RNA, which he named prions. This discovery of prions, initially met with skepticism, was a paradigm shift in the understanding of infectious agents and challenged the prevailing notion that only pathogens with nucleic acids could be infectious. Subsequent research confirmed Prusiner's findings, leading to his recognition with the Nobel Prize in Physiology or Medicine in 1997.
Prions are associated with severe neurodegenerative disorders known as transmissible spongiform encephalopathies (TSEs), such as Scrapie in sheep and variant Creutzfeldt-Jakob Disease (vCJD) in humans. These diseases have a long incubation period and are typically fatal.
It's important to note that prions do not follow traditional models of infection since they have no genetic material. Instead, the normal prion protein (PrPC, where C stands for cellular) is converted into an abnormal, disease-causing form (PrPSc, where Sc stands for Scrapie) when it encounters this misfolded variant within the brain tissue, which can also be ingested through contaminated food. This unprecedented mechanism for disease highlights the unique nature of prion diseases.