The isolation and characterization of a strain of subacute sclerosing panencephalitis measles-related virus.

The isolation of a measles-like virus in CV-1 cell cultures from a biopsy specimen obtained from a case of subacute sclerosing panencephalitis (SSPE) is reported. Evidence of the presence of cell-free virus was obtained from the fifth cell culture passage of the isolated virus. The virus was identified as measles-related by standard immune sera. IF study did not show relevant differences between the isolated virus and the Edmonston strain of measles virus, even though the proportion of cells showing nuclear antigen was higher following the infection with the isolated virus than with the Edmonston strain. Electron microscopy study failed to demonstrate viral structures in the cells from the brain biopsy, while numerous large aggregates of nucleocapsids were found in the cytoplasm of infected cells observed on the third and fourth passage in tissue culture. The neuropathogenicity assay carried out on newborn hamsters, rats and mice using a suspension of disrupted infected cells did not show any clinical pathological effect due to the SSPE strain. These results are partially in contrast with previous findings which indicate relevant differences in the morphology and pathogenicity of SSPE derived strains as compared to reference measles virus.