Tissue-Targeted Prime/Pull/Keep Therapeutic Herpes Simplex Virus Vaccine Protect Against Recurrent Ocular Herpes Diseases in HLA-A*0201 Transgenic Rabbits

Herpes Simplex Virus type 1 (HSV-1) continues to be one of the most prevalent viral infections globally, with approximately 3.72 billion individuals affected worldwide. A clinical herpes vaccine is still lacking. In the present study, a novel prime/pull/keep vaccine was tested in Human Leukocyte Antigen transgenic rabbit model of ocular herpes (HLA-A*0201 Tg rabbit). Ten asymptomatic (ASYMP) CD8+ T cell peptide epitopes and 3 CD4+ T-cell epitopes were selected from the HSV-1 glycoproteins D and B (gD and gB), viral tegument proteins (VP11/12 and VP13/14) and the DNA replication binding helicase (UL9), all preferentially recognized by CD8+ and CD4+ T cells from naturally protected HSV-1-seropositive healthy ASYMP individuals (who never had recurrent corneal herpetic disease). HLA Tg rabbits were ocularly infected with HSV-1 then during latency at day 30 post infection, the rabbits were ocularly vaccinated with a recombinant neurotropic AAV8 vector (107GC/ eye) encoding for the 10 CD8+ T cell peptide and 4 CD4+ T cells peptide (prime), T cell-attracting CXCL-11 (Pull) and T-cell keeping IL-2/IL-15 cytokines (keep). The rabbits were followed up for eye disease and viral loads in tears for 28 days. The frequency, function, and protective efficacy of HSV-specific CD8+ T cells induced by the prime/pull/keep vaccine were assessed in the trigeminal ganglia (TG), cornea, Spleen, and peripheral blood. Compared to the mock group (unvaccinated), the peptides/CXCL11/IL-2/IL-15 vaccine generated frequent resident CD8+ T cells that infiltrated the TG. CD8+ T cells mobilization and retention into TG of prime/pull/keep vaccinated rabbits was associated with a significant reduction in corneal herpes infection and disease after an ocular HSV-1 challenge (McKrae). These findings draw attention to the novel prime/pull/keep therapeutic vaccine strategy to mobilize and retain anti-viral T cells in tissues protecting them against herpetic infection and disease.