Eastern equine encephalitis virus infection: Electron microscopic studies of mouse central nervous system

Eastern equine encephalitis (EEE) virus infection of the central nervous system of newborn mice was examined by light and electron microscopy. Initial changes in brain architecture were due to interstitial and perivascular edema formation; the resulting extracellular space increased throughout the course of infection. Neuronal damage consisted of disruption of cytoplasmic organization and terminated in crenation, vacuolation, and membrane breakdown. Virus nucleoids (28 nm in diameter) were formed in the cytoplasmic matrix of all types of brain cells except endothelium, and viral maturation took place via nucleoid budding primarily through plasma membranes. Virus particles were 55 nm in diameter and were similar in morphology to other group A arboviruses.