This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology (General Propeies, DNA Viruses), Subject name: Microbiology
[{'content': 'In a neonate with "classic" symptoms of congenital cytomegalovirus (CMV) infection, which one of the following tests would be most useful in establishing a diagnosis? \nSelect and explain. \nA. CMV IgG titre on neonate\'s serum at bih, B. CMV IgG titre on mother\'s serum at bih of infant, C. CMV IgM titre on neonate\'s serum at bih and at 1 month of age, D. Total IgM on neonate\'s serum at bih', 'role': 'user'}, {'content': "Answer: C \nExplanation: CMV IgM titre on neonate's serum at bih and at 1 month of age is useful in establishing a diagnosis in a neonate. The results should indicate a rise in IgM titre. Cytomegalovirus (CMV) is the most common cause of congenital and perinatal viral infections. Measurement of total IgM in the infant's sera at bih is nonspecific and may show false-negative and false-positive reactions.", 'role': 'assistant'}]