Chronic wasting disease (CWD) in deer, elk, and moose is caused by a prion. Which of Koch's postulates would not work in regards to identifying the cause of CWD?

• A. Postulate 1.
• B. Postulate 2.
• C. Postulate 3.
• D. Postulate 4.

Answer: (B)

Verified step by step guidance

1. Understand Koch's postulates: They are a set of criteria established to identify the causative agent of a particular disease. The four postulates are: 1) The microorganism must be found in abundance in all organisms suffering from the disease, but not in healthy organisms. 2) The microorganism must be isolated from a diseased organism and grown in pure culture. 3) The cultured microorganism should cause disease when introduced into a healthy organism. 4) The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.
2. Identify the nature of prions: Prions are infectious proteins that cause neurodegenerative diseases. They do not contain nucleic acids and cannot be cultured in the traditional sense like bacteria or viruses.
3. Analyze Postulate 2: This postulate requires the pathogen to be isolated and grown in pure culture. Since prions are proteins and not living organisms, they cannot be cultured in the same way as bacteria or viruses.
4. Consider the limitations of prion isolation: Prions can be difficult to isolate in a form that is considered 'pure culture' because they are not cellular organisms and do not replicate independently outside a host.
5. Conclude which postulate is problematic: Given that prions cannot be cultured in the traditional sense, Postulate 2 would not work in identifying the cause of CWD, as it requires the pathogen to be isolated and grown in pure culture.