FCS raw data for Poulis, Robecchi et al, Nature Communications, 2026

Given the widespread clinical use, understanding its impact on translation fidelity is essential for vaccine safety. Recent studies suggested that m¹Ψ can promote ribosomal frameshifting, a translational error that generates aberrant peptides.

These peptides are presented on major histocompatibility complex and elicit immune responses, raising concerns about unintended antigenicity. To address this, we systematically examined the efficiency of frameshifting induced by m¹Ψ and the underlying mechanism, aiming to inform future mRNA vaccine design. Using mRNA-based dual-fluorescence reporters in cells, fully <i>in-vitro</i> reconstituted translation system,<i> </i>and single-molecule FRET microscopy, we show that m¹Ψ modestly increases +1 frameshifting on UUUC motifs in therapeutic mRNAs.