Immunologic modulation of virus-induced pathology in a murine model of acute herpetic retinal necrosis

Unilateral inoculation of herpes simplex virus Type 1 (KOS strain) into the anterior chamber of BALB/c eyes produces an ocular disease with a distinctive differential pattern of retinal pathology. Specifically, the retina of the inoculated eye remains histologically intact, whereas the contralateral retina becomes necrotic. We demonstrate that retinal necrosis in opposite uninjected eyes directly correlates with the presence of herpes simplex viral antigens, whereas the intact retinas of virus-injected eyes are devoid of immunocytochemically detectable viral antigens. Immunosuppression or lack of a thymus results in bilateral retinal necrosis, with positive immunoperoxidase staining for viral antigens in both eyes. We have shown previously that retinal protection in both eyes can be restored to irradiated recipients by adoptive transfer of spleen cells from mice primed by AC injection of HSV. Our results with reconstituted and normal mice suggest that virus-mediated cytopathic effects underlie contralateral retinal necrosis since HSV antigens are localized to areas of retinal necrosis and their presence precedes the local inflammatory response; immunosuppression does not alter the development of contralateral retinal necrosis. They also indicate that ipsilateral retinal preservation reflects T cell-mediated inhibition of viral spread to retinas of injected eyes. Reconstitution of irradiated recipients with AC primed donor cells prevents immunohistochemically detectable virus and retinal necrosis in both eyes. In all experimental groups we failed to detect viral antigens in the absence of retinal pathology.