Vascular and neuroglial changes in experimental herpes simplex encephalitis: ultrastructural study.

Generalized vascular changes and diffused proliferation of reactive microglia were observed in an experimental model of HSV encephalitis of mice. The wide spread of these changes contrasted with the localized character of virus replication and the confined areas of damaged nervous tissue. The vascular and microglial changes were precocious in animals inoculated with concentrated virus suspension (10(5.5)LD50) while they appeared late in mice inoculated with diluted virus suspension (100 LD50). After inoculation with U.V. inactivated virus no changes were seen. The results obtained in this study suggest that the vascular and microglial modifications are not related to a direct cytopathic effect of the virus but dependent on the amount of virus present in the central nervous system and linked to the virus DNA.