In vivo and in vitro models of demyelinating diseases. II. Persistence and host-regulated thermosensitivity in cells of neural derivation infected with mouse hepatitis and measles viruses.

Following inoculation of continuous cell lines of neural and other derivations, persistent infections are established with facility by mouse hepatitis and measles viruses. This occurs equally with the prototype MHV₃ and its neurotropic variant JHM as well as with the Edmonston vaccine and SSPE Hallé measles variants. In almost every instance that the infection becomes persistent at 32.5°, virus replication is found to be thermosensitive at 39.5°; however, progeny virus derived from such infections at 32.5° is itself thermostable when replicating in the indicator, fully permissive cell lines. The new data, therefore, reveal the existence of a host-conferred interrelationship between persistence and virus restriction at elevated temperature. They indicate that the two agents with neurotropic potential, when they become established as pathogens in the nervous system, could be under close host cell regulation involving as yet unknown mechanisms.