A staggering number of individuals?over 3 billion worldwide?are currently infected with herpes simplex virus type 1 (HSV-1), which causes frequent, and often lifelong, bouts of recurrent corneal herpetic disease. This potentially blinding disease is a result of corneal re-infection following reactivation of latent HSV-1 from sensory neurons of the trigeminal ganglia (TG). Our long-term goal is to develop a vaccine to protect against ocular herpes infection and disease. The most recent herpes vaccine clinical trials that used a recombinant HSV glycoprotein D (gD)-based subunit antigen vaccine mixed with monophosphoryl lipid A (MPLA) adjuvant and delivered intramuscularly failed to protect despite inducing strong HSV-specific neutralizing antibodies. Results from those clinical trials emphasize two major gaps in knowledge: (1) The need to design an alternative antigen delivery system that will induce cell-mediated immune responses (in addition to humoral responses). (2) The need to design an ocular herpes vaccine that will include T cell-induced HSV antigens (Ags), other than the gD. HSV-specific TG-resident CD8+ T cells play a critical role in aborting reactivation of HSV-1 from latently infected sensory neurons, and the involvement of ocular mucosal surface- (OMS-) resident CD4+ T cells is gaining wider acceptance. Our recently published and preliminary data demonstrate that: (A) CD8+ T cells from ?naturally protected? HSV-seropositive ASYMP individuals mainly recognize T cell epitopes from HSV tegument proteins VP16 and VP22. (B) Immunization of B6 mice with Self Assembling Protein Nanoparticles (SAPNs) that incorporate an HSV-1 CD8+ T cell epitope together with a CD4+ T helper epitope and flagellin/CpG1585 adjuvants induced strong and long-lasting CD8+ T cell responses and protected against ocular herpes. Building on the above published and preliminary data, we hypothesize that a SAPNs-based delivery system that incorporates human CD4+ and CD8+ T cell epitopes, recently identified in our lab from the VP16 and VP22 tegument proteins, can boost the number and function of protective TG- and OMS-resident CD4+ and CD8+ T cells and prevent or reduce recurrent ocular herpes disease. To test this hypothesis, we propose two Specific Aims:
Aim 1 : Test the hypotheses that therapeutic immunization of latently infected HLA double transgenic mice with SAPNs-based herpes vaccines delivering the VP16 and VP22 tegument proteins will boost HSV-specific TG- and OMS-resident CD4+ and CD8+ T cells and protect against UVB-induced recurrent ocular herpes infection and disease.
Aim 2 : Test the hypotheses that therapeutic immunization of latently infected HLA double transgenic mice with SAPNs- based herpes vaccines incorporating multiple pairs of immunodominant VP16 and VP22 CD4+ and CD8+ T cell epitopes will boost HSV-specific TG- and OMS-resident CD4+ and CD8+ T cells and protect against recurrent ocular herpes. Successful completion of the proposed work should help build a solid foundation toward developing an effective SAPNs-based ocular herpes vaccine.
Potentially blinding recurrent ocular herpes disease, caused by HSV-1 infection, is a major global health problem. This proposal will test a novel Self Assembling Protein Nanoparticles (SAPNs)-based ocular herpes immunotherapy that deliver (1) HSV VP16 and VP22 tegument proteins or (2) recently identified human CD4+ and CD8+ T cell epitopes from the HSV VP16 and VP22 tegument proteins. The pre-clinical projet will use our recently developed ?humanized? HLA transgenic (Tg) mouse model of UVB-induced recurrent ocular herpes. Results from this preclinical study will pave the way toward developing a novel SAPNs-based ocular herpes immunotherapy for clinical applications.