We propose to identify genetic and immunologic host factors responsible for the variable expression of ocular herpes simplex virus (HSV) infection, namely: primary acquisition of HSV ocular disease, expression of primary clinical infection, and propensity for recurrent disease. It is our basic hypothesis that certain specific genetic and immunologic factors regulate the expressivity and clinical course of ocular HSV disease. The role of these factors in expression of chronic and recurrent ocular herpes infection will be determined by the following studies: 1) Determination of the frequencies of serologically dependent HLA loci (A,B,C), lymphocyte-dependent histocompatibility locus D (B-cell alloantigen) in the clinical types of ocular HSV infections in man. 2) To determine if genetically determined factors relate to the clinical course aad severity of ocular herpes as well as predispose to recurrent and/or chronic disease. 3) Determination and correlation of the distribution of HLA-linked susceptibility genes in patients with recurrent and/or chronic HSV disease to genes governing immune responses to HSV antigens. Viral immunity will be evaluated by assessment of both humoral and cell-mediated immune responses.