Characterization of BNT162b2 mRNA to Evaluate Risk of Off-Target Antigen Translation

TLDR

mRNA vaccines are a safe and effective modality, yet manufacturing can generate fragment species from premature transcription or hydrolysis. The study investigates whether intact and fragmented BNT162b2 mRNA can translate truncated spike protein or off‑target antigens. Researchers isolated and characterized BNT162b2 fragment species and evaluated their translational viability using orthogonal expression systems. Only full‑length BNT162b2 transcripts are capable of expressing the SARS‑CoV‑2 spike protein; fragments arise from premature transcriptional termination and are not viable.

Abstract

<h2>Abstract</h2> mRNA vaccines have been established as a safe and effective modality, thanks in large part to the expedited development and approval of COVID-19 vaccines. In addition to the active, full-length mRNA transcript, mRNA fragment species can be present as a byproduct of the cell-free transcription manufacturing process or due to mRNA hydrolysis. In the current study, mRNA fragment species from BNT162b2 mRNA were isolated and characterized. The translational viability of intact and fragmented mRNA species was further explored using orthogonal expression systems to understand the risk of truncated spike protein or off-target antigen translation. The study demonstrates that mRNA fragments are primarily derived from premature transcriptional termination during manufacturing, and only full-length mRNA transcripts are viable for expression of the SARS-CoV-2 spike protein antigen.