Sindbis virus self-amplifying replicon is compatible with modified nucleotides mediating expression and vaccine responses in vivo.

The advent of effective formulations based on RNA encapsulated within lipid nanoparticles has led to the evaluation of this technology for its ability to treat and prevent a wide range of diseases. Expansion of the RNA-based tool kit available to vaccine and drug developers will accelerate this development and hopefully produce more robust and cost-effective therapies. With its more sustained expression profile, self-amplifying RNA offers many advantages to standard messenger RNA, allowing for the administration of lower RNA doses in vivo and potentially reducing dosing frequency for indications where long-term expression of a protein is required. We generated self-amplifying RNA containing the viral replicon from Sindbis virus, which demonstrated robust protein expression in vitro and in vivo. In addition, it showed increased compatibility with a number of modified nucleotides when compared to an equivalent RNA containing the replicon from Venezuelan equine encephalitis virus. These Sindbis-based self-amplifying RNAs containing modified nucleotides have the potential to be used in a variety of experimental and therapeutic applications.