After uptake, mRNA is translated into spike protein and presented as cell-surface MHC-bound peptides to CD4+ and CD8+ T cells. Cytosolic sensing of RNA by RIG-I and MDA5 plus TLR binding within endosomes leads to activation of IFN regulatory factor 3/7 (IRF3/7) and nuclear factor κB (NF-κB), which bind to DNA inducing gene transcription, and production of IFN-I and proinflammatory cytokines, respectively