Differences in early ultrastructural aspects of the replication of measles and subacute sclerosing panencephalitis viruses in a cell culture from a human astrocytoma.

Monolayer cultures from a human astrocytoma were infected with small amounts of Mantooth Subacute Sclerosing Panencephalitis (SSPE) and Edmonston measles viruses. The infected cells were studied with an electron microscope 48 hours and 96 hours post-inoculation (PI). By 48 hours PI, both viruses produced syncytia and cytoplasmic inclusions of granular nucleocapsids 20 to 25 nm in diameter which did not differ in appearance. With the Edmonston measles virus granular nucleocapsids assembled into budding particles were found just under the cell membrane while nucleocapsids of Mantooth SSPE virus spared the area under the cell membrane and were not incorporated into budding particles. Inclusions of smooth nucleocapsids, 15 nm in diameter, could be seen within the nuclei of Mantooth SSPE virus infected cells 96 hours PI; such nuclear inclusions were not found in the Edmonston measles virus infected cells. These results are compared with those obtained in other cell systems and are discussed with respect to recent findings in the field of SSPE.