Fig. 5
From: Replicon RNA vaccines: design, delivery, and immunogenicity in infectious diseases and cancer
Schematic illustration of immune responses induced by replicon vaccines. Innate immunity: the administration of recombinant replicon RNA induces the production of dsRNAs, which bind to different receptors in different intercellular locations: cytosolic dsRNA interacts with RIG-1 or MDA-5, endosomal dsRNA interacts with TLR3 or TLR7/8. Subsequently, signals relay to the nucleus, promoting the synthesis of IFN-Is, which then bind to IFNARs, activate the JAK/STAT pathway, leading to inhibition of mRNA translation, and RNA degradation. Adaptive immunity: antigen-presenting cells process the replicon vaccine particles to expose the recombinant subgenome and produce antigens. Antigen fragments presented in MHC-I and MHC-II activate cytotoxic T lymphocytes (CTLs) and helper T cells respectively. By combining the signals that originate from B cell receptors with the interaction of the integral antigen and the signals from helper T cells, B cells are activated