Nature communicationsJan 27, 2026

Engineered VPg saRNA enables precise, low-immune, cap-free production of therapeutic proteins in living organisms

mRNA Technology Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Jun 27, 2026

Abstract

Essence

An engineered VPg self-amplifying RNA vector may broaden mRNA therapy by enabling cap-independent, lower-immunogenic therapeutic protein expression in vivo.

Evidence

This platform experiment reports a Norovirus-replicon-derived VPg saRNA vector tested for therapeutic protein mRNA loading and in vivo applications including cachexia, oncolytic mRNAs, and graft-versus-host disease contexts.

Caveat

The abstract does not provide quantitative efficacy, safety, or comparator results for the disease models, so the therapeutic claim remains platform-level.

Simplified

Self-amplifying mRNA (saRNA) vectors hold promise for the sustained expression of mRNA vaccines in vivo. However, their inherently high immunogenicity and low-fidelity replication-stemming from the RNA viral genome's replication mechanisms-limit their efficacy as replacements or adjuncts to protein therapies. Here we report an engineered viral protein genome-linked (VPg) saRNA vector derived from a Norovirus replicon, designed for rapid loading of therapeutic protein mRNAs in vitro. The engineered VPg saRNA is adapted for a range of therapeutic scenarios, including treatment of tumor-associated cachexia under conditions of translational restriction in cap-dependent metabolism, precise encoding of oncolytic mRNAs in vivo to achieve complex functionality, and therapy for graft-versus-host disease in highly auto-immune environments. VPg saRNA addresses key limitations of linear mRNA and conventional saRNA therapies, broadening the potential applications of mRNA-based treatments.