Ocular HSV-1 infection, in conjunction with incompletely defined immune interactions, is a major cause of corneal scarring and blindness. Infection with HSV-1 does not induce a protective immune response against future primary infection at another site (or against recurrences at the same site). Thus, an effective vaccine against ocular HSV-1 infection may have to induce higher or different immune responses than those induced by natural infection. 5 of the 7 HSV-1 glycoproteins we have expressed in baculovirus protected against lethal challenge in an i.p. mouse model. gE, the only glycoprotein so far tested also protected against ocular HSV-1 infection. We hypothesize that one or more of our expressed HSV-1 glycoproteins will prove to be an effective vaccine against ocular HSV-1 infection and latency. Other than our work, no one has expressed more than 2 HSV-1 glycoproteins and only gB and gD have been tested against ocular HSV-1 infection.
Our specific aims to meet our broad, long term objectives to determine which glycoproteins will make the best vaccines and the specific immune response(s) that correlate with these vaccines' effectiveness and potential immunopathology include: 1. Screen our expressed HSV-1 glycoproteins as vaccines to protect against primary ocular HSV-1 challenge. Mice vaccinated with individual HSV-1 glycoproteins will be challenged ocularly with HSV-1. Screening of vaccine effectiveness (and ocular safety) will be based on a combination of decreased (1) death, (2) ocular disease, (3) virus replication in the anterior segment, (4) spread of virus to and replication in the posterior segment, the trigeminal ganglia, and the brain, and (5) decreased establishment of ganglionic latency. 2. Purification and screening of two selected expressed glycoproteins. Two selected expressed glycoproteins will be purified, using methods that avoid denaturation. Correlations will be made between ocular protection/immunopathology and humoral and cell mediated immune responses. 3. Determine the local immune response in the eye following vaccination and ocular challenge. Corneas from immunized and mock vaccinated mice will be examined by immunohistocytochemistry before and after ocular challenge with HSV-1 and quantitated for T-cell infiltrates, macrophages, and various cytokines. Passive antibody transfer and T-cell depletion studies will be done to confirm that correlations between the local immune response and ocular protection and/or immunopathology are mechanistic.
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