Innate pattern-recognition receptors sensing vaccine RNA (RNA-sensing PRRs)

Innate pattern-recognition receptors (PRRs) sensing vaccine RNA are a specialized group of immune sensors that detect exogenous RNA molecules to initiate the host's first line of defense (ResearchGate, 2024). This group primarily includes endosomal Toll-like receptors (TLR3, TLR7, and TLR8) and cytosolic RIG-I-like receptors (RIG-I and MDA5), which recognize distinct RNA features such as double-stranded structures or 5'-triphosphate ends (NIH, 2025; ResearchGate, 2025). Upon binding vaccine-derived RNA, these receptors activate signaling cascades that result in the secretion of type I interferons and pro-inflammatory cytokines (NIH, 2025). This process is essential for the 'adjuvant effect' of RNA vaccines, as it stimulates the maturation of dendritic cells and enhances the subsequent adaptive immune response (NIH, 2024). However, excessive activation can lead to significant reactogenicity or the suppression of antigen production, prompting the use of modified nucleosides in modern mRNA vaccines to minimize unwanted sensing (NIH, 2024; ResearchGate, 2023). These receptors are critical targets for optimizing vaccine efficacy and are also explored as therapeutic targets in oncology and infectious diseases (NIH, 2025; Frontiers, 2022).

Other names

RNA-sensing pattern recognition receptorsInnate RNA sensorsNucleic acid sensorsRNA-sensing PRRsInnate immune sensors of RNA

Activation of innate immune signaling pathways (MyD88, TRIF, and MAVS) leading to the production of type I interferons and pro-inflammatory cytokines, which act as an endogenous adjuvant for adaptive immunity (Alameh and Weissman, 2022; Okude et al., 2020).