HSV 1 LATENCY--IMMUNIZATION AND RECURRENT OCULAR DISEASE

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The long term ojbective of the proposed study is to reduce the high incidence of corneal blindness resulting from recurrent herpetic keratitis. The first proposed specific aim to meet this long term objective includes evaluating the feasibility of a live, attenuated herpesvirus vaccine by testing the hypothesis that primary colonization of the trigeminal ganglia with an avirulent HSV-1 TK- strain will effectively prevent secondary colonization with wild-type HSV-1 TK+ strains. Specifically, we will determine if more than one HSV-1 strain can occupy the same ganglion during latency, if an avirulent HSV-1 TK-strain will block colonization and/or reactivation of wild-type TK+ strains, and if a virulent challenge HSV-1 strain can complement or recombine with an avirulent immunizing virus strain to produce a latent virulent strain capable of producing recurrent ocular disease. Latent trigeminal herpesvirus(es) will be detected by both co-cultivation of trigeminal ganglia and iontophoresis-induced ocular shedding in tears. Recovered latent viruses will be characterized by TK phenotype and identified by restriction enzyme analysis. The role of species variations to explain contradictory results in the current literature will be evaluated in mice and rabbits. The second specific aim to achieve the long term objective of reducing blindness from recurrent herpetic keratitis includes elucidating the initial molecular events during reactivation of latent ganglionic herpes. A basic understanding of early gene transcription, including the reactivation signal and its control, is essential to achieve the second long-term objective. Specifically, we will study early virus RNA transcription in ganglionic neurons by in situ hybridization. The studies will be carried out in rabbits using 6 hydroxydopamine plus topical epinephrine iontophoresis model to induce reactivation of latent ganglionic herpesvirus. The results of both specific aims will lead to a better understanding of herpesvirus latency, and to an evaluation of the potential efficacy of a live virus vaccine.