A non-productive subacute sclerosing panencephalitis (SSPE) virus of human and ferret: an ultrastructural study.

A non-productive syncytiogenic measles virus isolated from the brain of an SSPE patient was grown on Vero cells. The ultrastructure of the infected syncytia was studied by electron microscopic and immunoperoxidase techniques. It was compared with the isolate of the virus after passage in ferrets, the Edmonston strain of wild measles virus and the Halle productive strain of SSPE, all on Vero cells. The immunoperoxidase labeling of the cell membranes of the Edmonston measles virus infected cells was very heavy and uniform. In contrast, the labeling of the non-productive SSPE infected cells was clearly discontinuous. In the latter, there was a preponderance of intranuclear over cytoplasmic nucleocapsid formation, whereas cytoplasmic nucleocapsids were prevalent in the virion-producing strains. Many similarities between Vero cells infected with the wild measles virus and the Halle strain of SSPE were observed, although differences between this SSPE strain and strains reported by others were noted.