Measles virus is a highly infectious viral disease characterized by a sore throat and a blotchy red rash that starts on the face and neck, and spreads to the rest of the body. It is a single viral serotype; either infection or immunization results in lifelong immunity. Human immune response to inactivated measles vaccine may produce atypical and severe disease after natural infection. The virus may cause acute infection depresses cellular immunity. It rash caused by cellular immune response to virus in the skin.
Measles virus causes an important acute exanthem of childhood and, rarely, a chronic, slowly progressive neurologic disease, subacute sclerosing panencephalitis (SSPE), which may follow decades after an acute infection. The highly infectious virus is spread via respiratory secretions. Acute infection is associated with significant morbidity and mortality, especially in individuals in developing countries. An effective live, attenuated vaccine is available; if used widely, it could prevent nearly all cases.
Measles virus is a paramyxovirus with an envelope and a negative-stranded RNA genome. It has a genome and protein composition typical of paramyxoviruses; the major envelope glycoproteins are a fusion (F) and attachment-hemagglutinin (H) protein. The H protein attaches to the cell receptor for measles virus, CD46. Only one serotype exists, although minor sequence changes may occur in the surface glycoproteins of the virus. Acute sinus infection of cells results in their death, commonly accompanied by syncytial giant-cell formation.
