A universal viral capsid protein based one step RNA synthesis and packaging system for rapid and efficient mRNA vaccine development.

The success of coronavirus disease 2019 mRNA vaccines highlights the transformative potential of mRNA technology. Current mRNA vaccine development involves complex steps, including plasmid construction, RNA transcription, 5' capping, poly(A) tailing, and lipid nanoparticle encapsulation, yet challenges in vaccine accessibility persist. Here, we present an innovative mRNA platform leveraging the self-assembly capabilities of the MS2 bacteriophage viral capsid protein (VCP). A dual-promoter plasmid has been designed where one promoter drives VCP expression while the other transcribes target RNA containing pac sites, enabling rapid mRNA self-assembly in Escherichia coli. Using an ovalbumin (OVA)-based tumor model, we validate the efficacy of this system. Tumor growth is significantly inhibited, accompanied by robust immune activation. Flow cytometry analyses reveal increased frequencies of OVA-specific CD8⁺, as well as activated and memory T cells. Additionally, the MS2-OVA vaccine favorably modulated the tumor immunosuppressive microenvironment by reducing myeloid-derived suppressor cells, while sustained antibody responses demonstrated the platform's ability to induce durable humoral immunity. These findings establish the feasibility of one-step mRNA synthesis and packaging in E. coli, providing a versatile and rapid platform for mRNA vaccine development, with broad implications for addressing global vaccination challenges.