The organ tropism of mouse hepatitis virus A59 in mice is dependent on dose and route of inoculation.

The organ tropism of MHV-A59, a murine coronavirus, was studied in 4-6 week-old C57BL/6 mice inoculated by different routes and with various amounts of virus. MHV-A59 caused hepatitis after intracerebral and intraperitoneal inoculation (two clearly artificial routes) and also after intranasal and intragastric inoculation (two routes more likely to mimic naturally acquired infection). For each route, the severity of hepatitis was dependent on the amount of virus inoculated. Significantly higher doses were needed to cause hepatitis by the intranasal or intragastric routes. We have shown previously that mice inoculated intracerebrally with MHV-A59 develop mild meningoencephalitis followed by chronic central nervous system (CNS) disease, characterized by primary demyelination (1). We extend these results here to show that acute CNS disease can be produced also by intranasal and intragastric inoculation, although much larger doses are needed as compared to intracerebral inoculation. Thus induction of demyelination, not only by the intracerebral route but also by the intranasal route, provides a useful model system to study virus-induced demyelination.