Final answer:
Stanley Prusiner was awarded the Nobel Prize for his discovery of prions as infectious proteins causing neurodegenerative diseases.
Step-by-step explanation:
Stanley Prusiner won the Nobel Prize for his discovery of an entirely new genre of disease-causing agents and the causative entity of transmissible spongiform encephalopathies, known as prions. His groundbreaking research focused on prion proteins, which showed that proteins alone, without associated nucleic acids, could be infectious and cause neurodegenerative diseases like Creutzfeldt-Jakob disease in humans and mad cow disease in cattle. This discovery fundamentally changed the understanding of infectious diseases and opened up new avenues for research and therapeutics in neurodegenerative diseases.