mRNA encoding norovirus VP1 produces antigenically functional virus-like particles in vitro

Human norovirus is a leading cause of acute gastroenteritis worldwide across all age groups, yet no licensed vaccine is available. The major capsid protein, VP1, self-assembles into highly immunogenic virus-like particles (VLPs) that have shown promise in clinical studies. Recently, mRNA has emerged as a compelling platform for norovirus vaccination. However, whether VP1-encoding mRNA can drive authentic VLP formation in human cells relevant to the vaccination environment has remained unknown. In this study, we used multiple human cell lines, including THP-1-derived macrophage-like cells, to model the post-vaccination environment. Transfection with norovirus GII.4 VP1 mRNA or lipid nanoparticle-formulated VP1 mRNA induced both intracellular and extracellular VP1 expression. Sucrose gradient purification and electron microscopy confirmed VLP assembly. These particles retained key antigenic and functional properties, including recognition by norovirus-specific antibodies in human serum and binding to histo-blood group antigens. Collectively, our findings provide direct evidence that VP1-encoding mRNA can generate structurally and functionally relevant norovirus VLPs in physiologically relevant human cell systems. These results strengthen the mechanistic rationale for mRNA-based norovirus vaccines and support their continued development.