PROJECT SUMMARY RNA vaccines have quicker development timelines and are simpler to manufacture than traditional vaccines. Combining this strength of RNA technology with protein engineering, they hold the potential to generate highly efficacious vaccines rapidly that can target and harness the immune system to counter their target virus. Further, since they can be rapidly synthesized, modifications can be made to maintain efficacy even when the target virus may undergo mutation in the population. Finally, as RNA vaccines are transient in the vaccinee, do not incorporate into the genome or require nuclear delivery, and do not encode an entire pathogen, they have a lower risk profile than other genetic immunization strategies. Therefore, a major component of this application is to generate efficacious RNA vaccine candidates. To accomplish this development (Aim1), our core will support Projects 1-3 by generating RNA for their potential engineering and screening. Once a lead antigen is selected, we will generate both mRNA and self-amplifying replicon mRNA (repRNA) encoding the same antigens to compare the safety and effectiveness of the immune response to the two different RNA vaccine platforms. To continue to innovate (Aim 2) and improve our mRNA and repRNA platforms to reduce reactogenicity, increase stability, and enhance translational efficiency of the RNA constructs, we will prepare antigen gene sequences with alternative, artificial intelligence-guided codon usage, and incorporate novel lipids into our lipid nanoparticles. Finally, we can assist our colleagues to make the transition from research to GLP studies by generating clinical grade RNA constructs in support of rigorous pre-clinical studies.