Alterations in the antigenic structure of two major HSV-1 glycoproteins, gC and gB, influence immune regulation and susceptibility to murine herpes keratitis.

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Abstract
We previously demonstrated that anterior chamber (AC) injection of HSV-1 before or simultaneous with topical corneal HSV-1 infection resulted in cellular immune tolerance of HSV-1 Ag and a reduced frequency of corneal stromal lesions. In the present study, we have investigated the role of the HSV-1 cell-surface glycoproteins gC and gB in the induction of tolerance, and the resulting reduced susceptibility to HSV-1 corneal stromal disease. These studies utilized mutant strains of HSV-1 with deletion or point mutations in the gene coding for gC or gB. Groups of mice received topical corneal infections with wild-type HSV-1, followed by AC injection of the same eye with wild-type HSV-1 or a mutant strain. Varying the antigenic composition of the virus injected into the AC resulted in three distinct patterns of immune responsiveness. In agreement with our previous findings, AC injection of wild-type HSV-1 induced a state of HSV-1 specific tolerance that extended to both the delayed type hypersensitivity (DTH) and CTL responses. A mutant strain lacking gC (gC-) induced partial tolerance characterized by undetectable CTL activity but a normal DTH response. A mutant strain lacking gB (gB-) caused partial suppression of the CTL response and no reduction of the DTH response. Thus, whereas gB may be involved in CTL tolerance induction in this model, gC clearly is not involved. In contrast, both gC and gB must be present in the AC to induce detectable DTH tolerance. The latter interpretation was strengthened by the observation that AC injection of a mixture of gC- (expressing normal gB) and gB- (expressing normal gC) effectively suppressed the DTH response to wild-type HSV-1. A panel of mar mutants with individual point mutations affecting gC and gB was used to identify the epitopes responsible for induction of DTH tolerance. Two of the gC mutants failed to induce DTH tolerance to wild-type HSV-1 when injected into the AC, suggesting that the sites on the gC molecule that are altered by these mutations are important for the induction of DTH tolerance. Similarly, one of the mar mutants for gB uniformly failed to suppress the DTH response, while another had a variable effect. The unique pattern of cellular immune reactivity exhibited by the mice receiving simultaneous topical corneal infection with wild-type HSV-1 and AC injection of gC- (no CTL but normal DTH) was associated with significantly reduced susceptibility to HSV-1 corneal stromal lesions.(ABSTRACT TRUNCATED AT 400 WORDS)