Comparative studies on subacute sclerosing panencephalitis virus and a usual measles virus with special reference to their capacities to produce viral hemagglutinin in Vero cells.

Various comparative studies were made on the capacities of a cell-associated subacute sclerosing panencephalitis agent (SSPE agent, Niigata/1 strain) and a usual measles virus (Toyoshima strain) to produce measles virus hemagglutinin (MV-HAnim) in Vero cells. The results obtained by various methods, such as the hemagglutination test (HA), hemadsorption test (HAd), antibody blocking test, antibody inducing test and fluorescent antibody technique (FAT) using monospecific antibody to MV-HAnin, consistently suggested that the SSPE agent was an incomplete measles-like virus having little if any MV-HAnin, but sharing immunologically closely related viral components other than MV-HAnin with those of the usual measles virus. The significance of these findings is discussed with respects to the latency of the SSPE agent.