Mouse Hepatitis Virus Type 4 Infection of Primary Glial Cultures from Genetically Susceptible and Resistant Mice

Mouse hepatitis virus type 4 infection of primary glial cultures, which consisted principally of astrocytes (marked by glial fibrillary acidic protein) from encephalitis-susceptible BALB/c or F1 (BALB/c x SJL/J) hybrid mice and resistant SJL/J mice, was studied. Primary neuron cultures from BALB/c and F1 hybrid mice were previously shown to be permissive and were destroyed within 5 days by infection with mouse hepatitis virus type 4, whereas neurons from SJL/J mice were fully resistant. In contrast, in the present study a chronic infection was established and maintained for up to 18 days in glial cultures from all three mouse strains. Infected SJL/J mouse glial cultures produced 10- to 50-fold less infectious virus and showed less cytopathic effect than did cultures from either infected BALB/c or F1 hybrid mice. Cytopathic effect was evident initially in cells from all three strains, and continued virus production occurred in the presence of limited additional cytopathic effect. These results were not due to the production of detectable levels of interferon. This study showed that SJL/J mouse primary glial cultures were permissive for mouse hepatitis virus type 4 infection whereas SJL/J primary neuron cultures were not, and that there was an early lytic phase of infection followed by chronic infection in all three strains.