IMMUNE CELL INFILTRATION IN CORNEAS OF MICE WITH RECURRENT HERPES-SIMPLEX VIRUS-DISEASE

Reactivation of latent herpes simplex virus type 1 (HSV-1) infection w as induced by UV irradiation of the corneas of latently infected mice. On days 1-4 after stimulation, infectious virus was sought in nervous and ocular tissue. On days 4, 7 and 10, eyes with either recurrent ep ithelial or stromal disease and appropriate controls were stained to i dentify immune cells and HSV-1 antigens. The maximum incidence of infe ctious virus was on day 2 when 5/10 ophthalmic parts of the trigeminal ganglion yielded HSV. Thus in this mouse model, as in humans, reactiv ation of virus in the trigeminal ganglion is the likely source of viru s producing recurrent disease and shedding in the tear film. On day 4, when virus antigens were still present, granulocytes were the predomi nant infiltrating cell in corneas with either type of disease. Small n umbers of T cells, dendritic cells and cells expressing MHC class II w ere also present. In stromal disease, the granulocyte infiltrate persi sted and T cells remained sparse. In contrast, in epithelial disease, granulocyte numbers rapidly declined and both CD4(+) and CD8(+) T cell s (present at a ratio of 1:1) increased significantly. The secondary i mmune response to virus antigen is more rapid and vigorous than that d uring primary corneal infection. Granulocytes may play a role in the i nitial clearance of virus, however, the other types of cells present e arly on provide the potential for a local secondary immune response. T he high proportion of CD8(+) cells in epithelial disease compared with stromal disease suggests that they may be acting as suppressors.