Experimental type 2 herpes simplex ophthalmitis in the newborn rat

An animal model for the study of type 2 herpes simplex virus (HSV2) ophthalmitis is described. Wistar rats were inoculated intracerebrally with HSV2 at 0, 5, 10, 15, 20, or 30 days of age. Eyes and brain from all animals, whether they survived or succumbed with encephalitis, were collected for microscopic and virologic studies. Up to 20% or more of the HSV2-inoculated rats had lesions in the cornea, uveal tract, and/or retina. Herpetic keratiis occurred in a few animals while the eyelids were still fused, indicative of internal spread of HSV2. Intranuclear inclusions were observed in corneal epithelium and neural retina, and herpesvirus particles were demonstrated in the cornea, iris, and retina. Lesions of the cornea and iris were also visualized by scanning electron microscopy. Virus was isolated from over 40% of the eyes tested. In general, titers of the virus in the eyes were less than those in the brains of HSV2-inoculated rats. The newborn rat thus represents another animal model to study herpetic ophthalmitis. Unlike most studies, ocular lesions were produced by a route other than the usual topical or intraocular inoculation of the virus.