Saturday, May 18, 2024
5/18/2024
ABSTRACT A staggering number of over 3.5 billion individuals worldwide are currently infected with herpes simplex virus type 1 and/or type 2 (HSV-1 & HSV-2), which cause genital herpes. Most HSV-seropositive individuals are asymptomatic (ASYMP) and never have any recurrent herpetic disease. In contrast, a small proportion is symptomatic (SYMP), with frequent, often lifelong bouts of recurrent herpetic disease, a result of reactivation of latent HSV from sensory neurons of the dorsal root ganglia (DRG). Our long-term goal is to develop a vaccine to protect against genital herpes. The most recent vaccine clinical trials that used a recombinant HSV- 2 glycoprotein D (gD2) -based subunit antigen vaccine mixed with monophosphoryl lipid A (MPLA) Adjuvant and delivered intramuscularly. This gD2 antigen delivery system failed to protect despite inducing strong HSV- specific neutralizing antibodies. This emphasizes 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 HSV vaccines that will include T cell epitopes from HSV antigens (Ags) other than gD2 and/or T cell epitopes. A critical role for HSV-specific sensory ganglia-resident CD8+ T cells in aborting reactivation of latent HSV has been established, and the involvement of vaginal mucosa- (VM-) resident CD4+ T cells is gaining wider acceptance. Our recent published and preliminary data demonstrate that: (A) CD8+ T cells from “naturally protected” HSV-seropositive ASYMP individuals mainly recognize CD8+ T cell epitopes from HSV tegument protein UL48 (VP16). (B) Immunization of B6 mice with Self Assembling Protein Nanoparticles (SAPNs) that incorporate an HSV 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 genital herpes. Building on the above published and preliminary data, we hypothesize that a SAPNs- based antigen delivery system and that incorporates human CD4+ and CD8+ T cell epitopes, recently identified in our lab from the UL48 tegument protein, can boost the number and/or function of protective DRG-resident CD4+ and CD8+ T cells and prevent or reduce genital herpes. To test this hypothesis, we propose 2 synergistic Specific Aims: Aim 1: To test the hypothesis that intravaginal immunization of HLA double transgenic mice with self- SAPNs-based herpes vaccines incorporating single pairs of human CD4+ and CD8+ T cell epitopes identified from HSV-2 UL48 (VP16) tegument protein will induce vaginal mucosa (VM) and DRG-resident CD4+ and CD8+ T cells and protect against genital herpes. Aim 2: Test the hypothesis that intravaginal immunization of HLA double transgenic mice with a SAPNs-based herpes vaccine incorporating multiple human UL48 CD4+ and CD8+ T cell epitopes in “string of pearls” will induce vaginal mucosa (VM) and DRG-resident CD4+ and CD8+ T cells and protect against genital herpes. Successful completion of the proposed work should help build a strong foundation toward developing an effective SAPNs-based genital herpes vaccine.
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