A novel HLA (HLA-A*0201) transgenic rabbit model for preclinical evaluation of human CD8⁺ T cell epitope-based vaccines against ocular herpes

We introduced a novel humanized HLA-A*0201 transgenic (HLA Tg) rabbit model to assess the protective efficacy of a human CD8⁺ T cell epitope-based vaccine against primary ocular herpes infection and disease. Each of the three immunodominant human CD8⁺ T cell peptide epitopes from HSV-1 glycoprotein D (gD_53-61, gD_70-78, and gD _278-286) were joined with a promiscuous human CD4⁺ T cell peptide epitope (gD_49-82) to construct three separate pairs of CD4-CD8 peptides. Each CD4-CD8 peptide pair was then covalently linked to an N^ε-palmitoyl-lysine residue via a functional base lysine amino group to construct CD4-CD8 lipopeptides. HLA Tg rabbits were immunized s.c. with a mixture of the three CD4-CD8 HSV-1 gD lipopeptides. The HSV-gD-specific T cell responses induced by the mixture of CD4-CD8 lipopeptide vaccine and the protective efficacy against acute virus replication and ocular disease were determined. Immunization induced HSV-gD_49-82-specific CD4⁺ T cells in draining lymph node (DLN); induced HLA-restricted HSV-gD _53-61, gD_70-78, and gD_278-286-specific CD8 ⁺ T cells in DLN, conjunctiva, and trigeminal ganglia and reduced HSV-1 replication in tears and corneal eye disease after ocular HSV-1 challenge. In addition, the HSV-1 epitope-specific CD8⁺ T cells induced in DLNs, conjunctiva, and the trigeminal ganglia were inversely proportional with corneal disease. The humanized HLA Tg rabbits appeared to be a useful preclinical animal model for investigating the immunogenicity and protective efficacy of human CD8⁺ T cell epitope-based prophylactic vaccines against ocular herpes. The relevance of HLA Tg rabbits for future investigation of human CD4-CD8 epitope-based therapeutic vaccines against recurrent HSV-1 is discussed.