This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Virology, Subject name: Microbiology
Subacute sclerosing panencephalitis virus (SSPE) is best described by which of the following statements? 
Select and explain. 
A. It is a progressive disease involving both white and gray matter, B. It is a late CNS manifestation of mumps, C. It is a common event occurring in 1 of 300,000 cases of mumps, D. Viral DNA can be demonstrated in brain cells
A: It is a progressive disease involving both white and gray matter
Answer: A: It is a progressive disease involving both white and gray matter 
Explanation: SSPE is a late and rare manifestation of measles. It is a progressive encephalitis involving both white and gray matter. Demyelination is seen only at an advanced stage of the disease in a few cases. In 1985, viral RNA was demonstrated in brain cells from a patient with SSPE by the use of in situ hybridization.