Research progress on immune mechanism and control strategy of dsRNA impurities in mRNA vaccine

INTRODUCTION: Double-stranded RNA (dsRNA) is a key impurity of mRNA vaccines prepared by in vitro transcription (IVT) and is primarily transcribed by T7 RNA polymerase. It can trigger innate immunity and induce a series of side effects that may influence the safety of mRNA vaccines. AREAS COVERED: This manuscript summarizes dsRNA generation mechanisms and immunity activation and analyzes the current challenges in dsRNA detection and control strategies. Regulatory standards for dsRNA impurities in mRNA vaccines have also been discussed. EXPERT OPINION: dsRNA as a critical quality attribute (CQA), the structural heterogeneity of it (including length and structure) and its precise immunomodulatory mechanisms affecting vaccine safety are poorly understood. Regulatory authorities have not released specific standards for dsRNA. Additionally, there is a lack of comparative analysis data on different corporate testing methods. Therefore, to ensure the safety of dsRNA containing mRNA vaccines and improve mRNA-based platforms, it is of great significance to establish standardized detection methods and standards for dsRNA; to design mRNA production with low dsRNA impurities by adopting the quality by design (QbD) approach; and to evaluate the immune stimulation mechanism of dsRNA impurities in mRNA vaccines.