Which test is used to detect distemper genome by detecting viral DNA?

• A. PCR
• B. ELISA for IgG
• C. ELISA for IgM
• D. CSF IgG versus serum IgG

Answer: (A)

Detecting a viral genome means directly identifying the virus’s genetic material rather than the immune response it provokes. PCR is the method that amplifies a specific viral sequence, making it possible to detect even very small amounts of viral nucleic acid. For distemper, which is an RNA virus, this is typically done as RT-PCR: reverse transcription converts the RNA genome to DNA, then PCR amplifies that material to confirm the virus’s presence. In contrast, ELISA tests for IgG or IgM measure antibodies and do not show whether the virus is currently present. Testing of CSF IgG versus serum IgG looks at antibody production within the CNS, not the viral genome itself. So the test that detects the distemper genome is PCR (with RT-PCR for RNA viruses).