A novel pentavalent circular RNA-based EBV vaccine

About This Grant

PROJECT SUMMARY: Epstein-Barr virus (EBV) infection is associated with infectious mononucleosis, several autoimmune diseases, and multiple cancers. Yearly, there are ~350,000 new cases of EBV-associated cancers, and ~200,000 deaths from such cancers. Despite the health burden posed by EBV infection, there is no licensed prophylactic vaccine against primary EBV infection. Previous clinical efforts focused on only one glycoprotein (gp) vaccine target (i.e., gp350) and yielded unsatisfactory results. To improve EBV vaccine immunogenicity and protective efficacy, our efforts have focused on developing a single vaccine that combines gp350 with four additional gps that are key for viral entry and are all targets of neutralizing antibodies (nAbs): gB, gp42, and gHgL. Our studies using virus-like particle- and viral vector-based platforms have confirmed that a multivalent approach is immunogenic in multiple animal models, eliciting antibodies with superior in vitro and in vivo neutralizing activity than those elicited by gp350-monovalent vaccine controls. In the proposed project, we seek to employ circular RNA (circRNA), a novel RNA-based vaccine platform that improves upon traditional virus-like particle-, viral vector-, and RNA-based platforms, as a platform for pentavalent EBV vaccine development. Our hypothesis is that immunization with a pentavalent circRNA EBV vaccine expressing five gps involved in viral entry will elicit protective antibody-mediated humoral responses with nAb activity in vitro, ex vivo, and in vivo as tested in three EBV challenge models. We will test this hypothesis using unique yet complementary EBV challenge animal models that will allow us to comprehensively assess vaccine immunogenicity and efficacy against systemic infection acquired through non-natural (intravenous, rabbit) and natural (oral, common marmoset) routes, and against infection of human B cells (humanized mice). In Aim 1, we will first characterize the immunogenicity of the pentavalent circRNA-based EBV vaccine in immunized rabbits; then, we will characterize the in vivo protective efficacy of the vaccine against systemic EBV infection in immunized rabbits after intravenous viral challenge, as well as against human B cell infection in humanized mice after passive immunization with immune rabbit sera followed by viral challenge. In Aim 2, we will similarly assess vaccine immunogenicity and in vivo protective efficacy in common marmosets after immunization and oral EBV challenge. In both Aims, we will compare immunogenicity and efficacy of our circRNA-based vaccine candidate to that elicited by other pentavalent comparators and gp350-based monovalent controls. In summary, our short-term goal is to characterize a novel pentavalent circRNA-based EBV prophylactic vaccine and assess its immunogenicity and efficacy in three complementary animal models, paving the way for future clinical translation. Successful completion of this project will help advance our long-term goal to develop effective vaccines that prevent or limit primary EBV infection and its associated diseases.