Figure 1.

Schematic illustration of the 4N4T‐DS mRNA vaccine against SARS‐CoV‐2 variants. A) DS mRNA is encapsulated in 4N4T ionizable lipid nanoparticles, thus forming 4N4T‐DS mRNA vaccines. LNPs containing DS mRNA are taken in by antigen‐presenting cells after vaccination and DS mRNA is released in the cytoplasm. B) S proteins are translated by ribosomes, processed into antigen peptides, and then integrated on cytomembrane or secreted outside the APCs. C) APCs present antigenic peptides to cytotoxic T cells and helper T cells via the MHC I route and MHC II route, respectively. B cells receive the first signal from S proteins through BCR and the second signal from activated helper T cells via CD40. D) Then, B cells are activated and subsequently differentiate into plasma cells, and S‐specific neutralizing antibodies are produced. Besides, cytotoxic T cells can eliminate the infected cells.