[Subacute sclerosing panencephalitis. A case with a prolonged course in an adult. Isolation and characteristics of a "defective" measles virus (author's transl)].

A 33-year-old man had a 6-year history of clinical signs suggesting multiple sclerosis : visual lesion at 27 years of age, cerebellar and visual disturbances at 31, which partly regressed, lymphocytosis and increased-gammaglobulin levels in the cerebrospinal fluid. Biological and anatomical (optical and ultrastructural) examinations gave results typical of a subacute sclerosing panencephalitis. A cytopathogenic measles virus was isolated from a cerebral biopsy specimen. The agent was transmissable to vero cells by co-culture but infectivity was always related to the cells and was therefore an incomplete viral infection. Virus-like particles were found in the nucleus and cytoplasm after electron microscopy examination of the co-cultures. Biochemical tests demonstrated that the viral proteins were all synthesized except hemagglutinin, which is a characterist abnormality of a "defective" measles virus.