Histopathological study and virus titer determination in organs were carried out on hamsters inoculated with JE virus via intracerebral, subcutaneous, intranasal and intraperitoneal route, with and without subcutaneous administration of hyaluronidase.
In groups inoculated with JE virus intracerebrally or intraperitoneally, perivascular cell infiltrtions in liver and brain, pneumonitis, meningitis and nephritis were observed 2 days after inoculation with low stainability of infected cells in nucleic acid stained preparations. Following subcutaneous inoculation of virus, similar, though retarded, changes were observed approximately 4 days after inoculation. Intraperitoneal inoculation exhibited on the 2nd day the same findings as those observed in the intracerebral inoculation of virus. By addition of hyaluronidase a marked loosening of blood vessels and fatty degeneration of parenchymal cells were observed.
In the case of intracerebral inoculation the titer of the virus in the brain tissue was LD₅₀/ml, while in the other organs 10²-10³LD₅₀. In other groups the brain showed the highest virus titer (10⁴LD₅₀), even when clinical symptoms were lacking. The quantity of virus in various organs was in the following order: blood>lung>liver>kidney.