Abstract
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.
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Source data for Figs. 1–7 and Supplementary Figs. 1–7 are provided as Source Data files. LC–MS/MS raw datasets and Sanger sequencing chromatograms generated in this study have been deposited in Figshare and are available at https://doi.org/10.6084/m9.figshare.3078216546 and https://doi.org/10.6084/m9.figshare.3069415146. Raw fluorescence microscopy, cryo-transmission electron microscopy (cryo-TEM), immunohistochemistry (IHC), and hematoxylin and eosin (H&E) staining images are not publicly available due to large file sizes, instrument-specific formats, and institutional data management restrictions; however, all processed and representative images supporting the findings of this study are included in the paper and its supplementary materials. All other data, including raw imaging data, are available from the corresponding author upon request. Source Data are provided with this paper.
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Acknowledgements
This research was supported by the National Natural Science Foundation of China (32471002, 82401829, 82472617, and 82404553; F.Z.Y.), the National University of Singapore (NUHSRO/2020/133/Startup/08, NUHSRO/2023/008/NUSMed/TCE/LOA, NUHSRO/2021/034/TRP/09/Nanomedicine, NUHSRO/2021/044/Kickstart/09/LOA, 23-0173-A0001; C.X.Y.), the National Medical Research Council (MOH-001388-00, CG21APR1005, MOH-001500-00, MOH-001609-00; C.X.Y.), the Singapore Ministry of Education (MOE-000387-00; C.X.Y.), the National Research Foundation (NRF-000352-00; C.X.Y.), the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang (2023R01002; Z.G.W.), the Distinguished Young Scientists Fund of Zhejiang (LR25H250001; Z.G.W.), and the National Science and Technology Major Project of China (No. 2025ZD1802201; Z.G.W.).
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Z.Y.F. conceived and designed the overall study, supervised key experiments, and led data analysis and interpretation. Z.Y.F. and L.X.C. performed most molecular and cellular experiments. J.Z. and P.W. assisted with cell culture and animal studies. Q.L., Z.L.X., L.Y., and Y.J.H. contributed to data processing, statistical analysis, and figure preparation. X.B.Z., J.H.Z., and Q.C. provided essential reagents, technical guidance, and methodological support. Y.B.P. performed imaging and histopathological examinations. X.K.L., Z.G.W., and X.Y.C. jointly supervised the project, contributed to conceptual refinement, and provided funding and resources. Z.Y.F. wrote the manuscript with input from all authors. All authors discussed the results, revised the manuscript, and approved the final version.
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Xiaoyuan Chen is a co-founder of and holds shares in Yantai Lannacheng Biotechnology Co., Ltd. The remaining authors declare no competing interests.
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Feng, Z., Chu, L., Li, Q. et al. Engineered VPg saRNA achieves cap-independent, low-immunogenic and precise encoding of therapeutic proteins in vivo. Nat Commun (2026). https://doi.org/10.1038/s41467-026-68364-w
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DOI: https://doi.org/10.1038/s41467-026-68364-w
