Self-amplifying RNA

Self-amplifying RNA (saRNA), also termed self-replicating RNA (srRNA), is a type of mRNA molecule engineered to replicate itself within host cells, enhancing protein expression and boosting the immune response, making it a promising tool for vaccines and other therapeutic applications. As a "next-generation" mRNA, saRNA is designed to achieve greater protein expression with a reduced dose compared to conventional mRNA. Unlike conventional mRNA, which has a short half-life and limited ability to express proteins for an extended time, saRNA can sustain protein expression for longer periods. saRNA are based on positive single stranded RNA viruses most commonly alphaviruses such as Venezuelan equine encephalitis virus.

Conventional messenger RNA (mRNA) vaccines only produce a finite amount of protein due to the short mRNA half-life. saRNA extends the kinetics of expression by a second ORF encoding the protein machinery necessary for its own replication. This self-replication dramatically increases both the amount of RNA and the time of expression. Consequently, the amount of protein produced from the initial dose is reduced as compared to conventional mRNA.