Poster X3 - Engineering potent mRNA vaccines through innovation in delivery material and RNA design

Introduction: Infectious disease remain the biggest threat to public health claiming thousands of lives annually, hence development of protective vaccines is a global priority. Strategies that can address challenges such as viral resistance, waning immunity, pan-strain efficacy and reactogenicity (adverse reactions), can offer lasting and sustainable resolution to this issue. Notably, success of COVID-19 vaccines highlights the potential of LNP-mRNA technology as a versatile platform for rapid and scalable vaccine development. These emerging vaccine platforms typically comprise of two major components - (i) mRNA sequence for immunostimulation and antigen production, and (ii) lipid nanoparticles for RNA delivery. While mRNA transcripts can be engineered to stimulate novel immune pathways and generate novel antigen constructs. LNPs can be engineered to overcome delivery challenges and generate desired adaptive immune response. Here, we have taken a multi-pronged approach to develop next-generation vaccines through innovation in both delivery vehicle and mRNA design. We developed novel LNPs which generated 10-100-fold stronger immune response as compared to the current FDA approved mRNA vaccine formulations. Subsequently, we designed mRNA which encoded for (i) immunostimulatory pathways to activate myeloid cells and (ii) germline B and T-cell peptide antigens, which generated broadly reactive immune response in humanized mice models. Overall, our study offers novel insights for developing potent mRNA vaccines by (i) improving delivery efficacy, (ii) appropriate immunostimulation and (iii) optimized antigen design to develop mRNA-vaccines that generate potent and durable immunity.

Materials and

Methods: To develop potent lipid nanoparticles, we have utilized combinatorial chemistry to generate a vast array of novel ionizable lipids which exhibit high mRNA transfection in vivo upon intramuscular administration. Subsequently, we optimized the molecular structure of top ionizable lipid using medicinal chemistry approach and perform structure-immunogenicity studies to generate potent vaccine LNP formulations. Next, we generated mRNAs which encoded for novel immunostimulatory pathways and antigen constructs. Mice vaccinated with these novel mRNAs were evaluated for immune response.

Results, Conclusions, and Discussions: Engineered LNPs generated 10-100-fold higher humoral and cellular response as compared to FDA approved LNP formulations. This superior immune response was attributed to enhanced antigen production combined with the immunostimulatory nature of the ionizable lipids that generated strong and persistent germinal centers, necessary for a stronger immune response. Co-delivery of mRNAs encoding immunostimulatory pathways and SARS-CoV-2 spike protein, generated stronger immune response at a much lower dose as compared to the immune response generated by mRNA encoding spike protein alone. Subsequently, we vaccinated humanized mice using a germline targeting immunogen which generated 5-10-fold higher bnAb (broadly neutralizing antibody) precursor B-cells as compared to clinically used immunogens. Finally, we designed novel mRNA sequences encoding networked peptide epitopes to generate T-cell based vaccines. By varying the copy number for each epitope in these cassettes, we were able to generate potent cellular response against sub-dominant viral epitopes. Overall, our study offers novel insights into engineering of delivery vehicles and RNA design to develop mRNA-vaccines that generate potent and durable immunity against multiple infectious diseases.

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