Persistent infection with mouse hepatitis virus, JHM strain in DBT cell culture.

After inoculation with JHM strain into DBT cell monolayers, a persistently infected DBT cell culture was established without producing typical cytopathic changes after about 15th passages. By immunofluorescence virus specific antigen was demonstrated in 10 to 15% DBT cells. This persistently infected culture (JHM-CC) was resistant to superinfection with parental JHM, but such resistance was not shown against vesicular stomatitis virus. JHM-CC virus produced small plaques on DBT cell monolayers. Temperature sensitive (TS) mutant, defective interfering (DI) particle or interferon was not detected in the JHM-CC. To intracerebral inoculation with JHM-CC virus, cortisone treated ICR mice survived without showing clinical signs, however, demyelinating lesions were produced in the brain and spinal cord of them.