This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
[{'content': 'Mad Cow Disease has been highly publicized in Great Britain. This disease, which is similar to scrapie, is caused by \nSelect and explain. \nA. A prion, B. A virus, C. Rickettsiae, D. An autoimmune reaction', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mad Cow Disease is related to both scrapie in sheep and bovine spongiform encephalopathy virus. The fear in Great Britain is the potential for acquiring Creutzfeldt-Jakob disease, which is a slowly progressive neurodegenerative disease. Theoretically, such acquisition could be through ingestion of beef from infected cows. A prion consists of protein material without nucleic acid. While related to a virus, a prion is a proteinaceous infectious particle that replicates within cells.', 'role': 'assistant'}]