Which statement best describes Johne's disease in the context of immunogenicity?

• A. It demonstrates a persistent infection with poor immune response
• B. It demonstrates a strong acute immune response
• C. It is highly immunogenic and clears quickly
• D. It is not associated with chronic infection

Answer: (A)

The key idea is that Johne’s disease represents a long-lasting infection where the immune response fails to clear the pathogen. MAP establishes itself inside macrophages and triggers granulomatous inflammation in the gut, but the response is not sufficient to eradicate the bacteria. This leads to a persistent, chronic infection rather than a rapid, effective, acute clearance. So, describing it as a persistent infection with a poor immune response best fits immunogenicity in this context. It’s not a situation of a strong acute response, nor of high immunogenicity with quick clearance, and it is indeed associated with chronic infection.