Fig. 1.

(A, B) Schematic diagrams of in-vitro-transcribed mRNA: (A) non-replicating mRNA and (B) self-amplifying RNA. (C) Replication of self-amplifying RNA inside cells. (1) After translation, non-structural proteins 1-4 (nsP1-4) are produced, forming the early replication complex that synthesizes (-) strand of mRNA transcript. (2, 3) The late replication complex produces (2) genomic (+) strand and (3) subgenomic (+) strand. Genomic transcript continues further replications and subgenomic transcript initiates antigen production.