SSPE, measles virus, and the matrix protein: report of a case with unusual immunochemical findings.

We report a case of atypical subacute sclerosing panencephalitis (SSPE) in which the diagnosis was confirmed by a new radioimmunoprecipitation method. Antimeasles antibody was absent in the cerebrospinal fluid (CSF) when measured by conventional immunoassay techniques, there was no clinical response to isoprinosine, and the patient showed a selective absence of CSF antibody response to the matrix protein and only a partial serum antibody response to this measles polypeptide. The value of this sensitive immunoprecipitation method in profiling the selective antibody responses to the several measles polypeptides and the advisability of using isoprinosine, an immunopotentiating agent, to treat SSPE are discussed.