Measles and subacute sclerosing panencephalitis virus proteins: lack of antibodies to the M protein in patients with subacute sclerosing panencephalitis.

Studies on the immunoprecipitation of the proteins of several different measles and subacute sclerosing panencephalitis (SSPE) virus strains from lysates of infected cells have revealed a relative lack of antibodies to the nonglycosylated viral membrane protein (M) in the sera of patients with SSPE, in contrast to a high level of antibodies to other viral proteins. No evidence was found for the existence of a large number of antigenically unique M proteins. In contrast to SSPE sera, other hyperimmune human or rabbit sera precipitated M protein as well as the other viral proteins. The results suggest that in patients with SSPE there is either diminished synthesis of M, or it is not recognized normally by the immune system, and that an abnormality in M protein is involved in the pathogenesis of SSPE. Although differences in electrophoretic mobility of the M proteins and several other viral proteins were observed among different SSPE and measles strains, there was no pattern characteristic of SSPE strains, nor could these strains be distinguished by peptide mapping.