Developing a Multi-epitope Pan-Coronavirus Vaccine

SUMMARY Humanity is confronting a pandemic caused by the new Corona Virus 2 (SARS-CoV-2) infection. Our long- term goal is to develop a potent prophylactic pan-Coronavirus vaccine to stop/reduce past, current and future Coronavirus infections and/or diseases. While SARS-CoV-2-induced antibody and CD4+ and CD8+ T cell responses are critical to reducing viral infection in the majority of asymptomatic individuals, an excessive proinflammatory cytokine storm appears to lead to acute respiratory distress syndrome in many symptomatic individuals. Major gaps: Identifying the epitope specificities, the phenotype and function of B cells, CD4+ T cells and CD8+ T cells associated with "natural protection seen in asymptomatic individuals (those who are infected, but never develop any major symptoms) should guide the development of a future coronavirus vaccine. Preliminary Results: We have made significant progress in: (A) Identifying a priori potential human B-cell, CD4+ and CD8+ T cell target epitopes from the whole SARS-CoV-2 genome; (B) Identifying "universal" epitopes conserved and common between: (1) previous SARS and MERS coronavirus outbreaks, (2) current 4388 SARS-CoV-2 strains that now circulate in the United States and 184 other countries; and (3) SARS-like coronavirus strains currently found in bats that have the potential to produce future human outbreaks; (C) Applying our scalable self-assembling protein nanoparticles (SAPNs) antigen delivery platform to produce prototype multi-epitope pan-Coronavirus vaccine candidates, that incorporate conserved protective epitopes from human and bats Coronaviruses, and demonstrated their B- and T-cell immunogenicity in HLA transgenic mice; and (D) Generating a novel "humanized" susceptible HLA-DR/HLA-A*0201/hACE2 triple transgenic mouse model in which to test these vaccine candidates. Our hypothesis is that one of our pan-Coronavirus vaccine candidates, containing conserved "asymptomatic" SARS-CoV-2 B- and T-cell epitopes that are mainly recognized by the immune system of "protected," asymptomatic individuals would protect from SARS-CoV-2 infection and disease, upon intranasal delivery. To test this hypothesis our Specific Aims are: Aim 1: To test in vitro the antigenicity of conserved Coronavirus epitopes, we recently identified from the whole SARS-CoV-2 genome, using blood-derived antibodies, CD4+ T-cells and CD8+ T-cells from SARS-CoV-2-infected symptomatic vs. asymptomatic individuals. The immunodominant conserved "asymptomatic" epitopes will be identified and used in our multi-epitope pan-Coronavirus vaccine candidates. Aim 2: To test in vivo the safety, immunogenicity, and protective efficacy of highly conserved multi-epitope pan-Coronavirus vaccine candidates, delivered mucosally, to our novel "humanized" susceptible triple transgenic mouse model. Successful completion of this preclinical vaccine project is expected to identify a broadly protective pan- Coronavirus vaccine candidate that could quickly proceed into an FDA Phase 1 clinical trial.