OCULAR INOCULATION OF MONKEYS WITH SIMIAN VARICELLA VIRUS - CLINICAL AND HISTOPATHOLOGIC OBSERVATIONS

Purpose. To explore the possibility that inoculation of the eyes of Af rican green monkeys with simian varicella virus (SW) induces the sympt oms of herpes tester ophthalmicus (HZO), as seen in humans, and to dev elop a realistic and reproducible animal model of herpes tester ophtha lmicus for experimental studies,Methods. In the first experiment, the right eyes of three African green monkeys were inoculated by intrastro mal and subconjunctival injections with a suspension of SW-infected Ve ro cells. In the second experiment, three additional monkeys were pret reated with intramuscular injections of methylprednisolone (41 mg/kg) for 7 days before ocular inoculation with SW and for 3 weeks at 14 mg/ kg after virus inoculation. The eyes were examined by slit-lamp biomic roscopy. Histologic, immunohistochemical, and electron microscopic stu dies were performed. Results. In the first experiment, all three anima ls developed high titers of anti-SVV antibodies (IgG). Diffuse stromal opacity, with keratitic precipitates, stromal edema, and mild vascula rization of the cornea, appeared 12 to 14 days after inoculation. The onset of ocular disease was correlated with the rise in serum antibody levels. There was no clinical evidence of a systemic viral infection resulting from the corneal inoculations in these monkeys. In the secon d experiment, all three animals treated with methylprednisolone develo ped severe ocular pathology within 1 week of inoculation. The clinical appearance of the diseased eyes strongly indicated that local viral i nfection had occurred. Dendritiform keratitis, corneal erosion, and st romal necrosis with vascularization of the cornea was seen in all the eyes. The disease resolved within 4 to 5 weeks of inoculation, leaving opaque, vascularized corneas. Histologic studies showed that inflamma tory cells and viral antigens were widespread throughout the diseased corneas. A high titer of anti-SVV antibody (IgG) was detected in the i mmunosuppressed monkeys, but no evidence of systemic viral infection w as observed. Conclusions, The authors propose that inoculation of the eyes of methylprednisolone-treated African green monkeys with simian v aricella virus provides an appropriate animal model for studies of the virology and immunopathology of ocular varicella virus infection.