This is the main reason for vaccination. There is little or no production of virus in the brain but myelin basic proteins are affected and patients T-cells are reactive to myelin, thus is auto immune disease. Subacute Measles encephalitis occurs only in immunocompromised children, usually with 6 months of the rash, failure of the immune system to get rid of virus. Finally SSPE, occurs years after the disease, it is almost always fatal. Characterized by spread of measles virus in the brain.
SOme neurons contains large accumulation of measles nucleocapsid.
Sequencing reveals many mutations in the M protein., and to lesser extent in other genes. Essentially all primary measles infections give life long immunity. Only one sera-type. Do not find antigen dirft. In third world countries it is a major problem.