Diagnosis of BSE can be made based on which of the following?

• A. Clinical signs and disease progression
• B. Immunoblot or immunohistochemistry of third eyelid lymphoid tissues antemortem
• C. Antibody titers, acute and convalescent
• D. Immunoblot or immunohistochemistry of the brain

Answer: (D)

Diagnosing BSE hinges on detecting the disease-associated prion protein in brain tissue. The abnormal prion (PrPSc) accumulates in the brain in a way that can be demonstrated reliably using immunoblot (Western blot) or immunohistochemistry, making brain testing the definitive confirmation. Clinical signs are not specific to BSE and can resemble other neurological diseases, so they can’t confirm the disease on their own. Additionally, animals don’t mount a meaningful antibody response to prions, so antibody titers aren’t useful for diagnosis. Testing third eyelid lymphoid tissue antemortem can aid surveillance but is not as definitive or sensitive as brain testing, which is why brain immunoblot or immunohistochemistry is the best answer.