Regulation of innate immunity by self-adjuvated MRNA vaccines

ABSTRACT Mycobacterium tuberculosis (MTB), the causative agent of pulmonary and non-pulmonary tuberculosis (TB), kills nearly 1.2 million people every year, whereas ~ one-third of the global population is latently infected with Mtb. Bacillus Calmette-Guérin (BCG) is widely used as a vaccine against TB, and over one billion doses have been used so far although it only partially protects children from TB but not adults. We discovered that a novel-self adjuvanted mRNA (SamR) vaccine delivering MTB-derived antigen can protect mice against TB. In this proposal, we propose to develop new generation mRNA-based vaccines route to protect against TB using a multi-antigen-based platform which also integrates an adjuvant. A ‘systems immunology’ approach will be used to evaluate innate immunity mechanisms that control adaptive immune responses in mice vaccinated using our improved mRNA vaccines. Our goals are: Specific Aim-1: To develop a new generation mRNA-based vaccines expressing protective antigenic epitopes of Mycobacterium tuberculosis (MTB) in combination with in-built adjuvant peptides. We will develop multiple MTB protein antigen expressing mRNA vaccines that contain a unique self-adjuvant to boost immune responses. We will synthesize and evaluate more efficient linear mRNA and/or circular RNA vaccines for tuberculosis and formulate them in nanoparticles. Specific Aim-2: To characterize the molecular mechanisms of new generation mRNA vaccines. We found that our new generation SamR-vaccines induced a robust activation of innate immunity pathways (RIG-I NOD2 and TLR) in macrophages and dendritic cells. We will investigate the molecular mechanisms of protein antigen-induced Immunogenicity and C5- induced adjuvanticity using APCs from wild type C57Bl/6 mice, and transgenic mice that lack innate nodal genes. Specific Aim-3: To determine the efficacy of SamR-vaccines against tuberculosis in wild type and immunodeficient mice. We found that our novel vaccine activated trained immunity genes in macrophages. Because BCG-induced trained and adaptive immunity declines in human children by age 5 predisposing them to TB, we will investigate the boosting effect of our trained immunity inducing SamR-vaccines for protection in BCG vaccinated mice. We will use both C57BL/6 and our optimized immune competent and immunodeficient humanized model to identify parameters of protection relevant to humans.