Fig. 1

Immunohistochemical and histologic findings in mice after IN infection with EEEV strain FL93-939. Mice were infected with approximately 100LD₅₀ and were euthanized at specified time points (n = 5). Viral antigen was first detected in the nasal cavity at1 dpi (box) (a magnification X100), specifically the olfactory epithelium and underlying lamina propria (arrow) (b magnification X400). A significant amount of viral antigen was present in the nasal cavity by 2 dpi, but was restricted to the olfactory epithelium (arrows); the respiratory epithelium was not involved (arrow head) (c magnification X40). Viral antigen was first detected in the olfactory bulb at 2 dpi (d magnification X400). Viral antigen was present throughout the brain by 5 dpi (e magnification X20) and there was significant neuronal cell death (hypereosinophilic, shrunken neurons with pyknosis or karyorrhexis, arrow) in the hippocampus (f magnification X200)