NSUN2-dependent 5-methylcytosine Modification Regulates Influenza A virus Gene Expression and Genomic Packaging

Le résumé fourni par la source

Abstract Emerging evidence indicates that methyltransferase NSUN2 catalyzes 5-methylcytosine (m 5 C) modifications on various viral RNAs and plays important roles in viral biology. However, the regulatory roles of NSUN2 in influenza A virus (IAV) replication have not been elucidated. Here, we revealed that NSUN2 negatively regulated the viral RNA transcription and protein production by knocking out and over-expressing NSUN2 . By m 5 C MeRIP-seq and RNA-BisSeq, NSUN2-dependent m 5 C sites were identified on both the plus and minus viral RNA strands. In NSUN2- KO cells, the m 5 C modification on vRNAs was reduced, resulting in the production of a large number of deficient interfering particles (DIPs) which had lower vRNA content, imbalanced genome fragments, abnormal morphology and reduced pathogenicity. Mutation of m 5 C sites at the 5’ and 3’ ends of PB2 vRNA interfered with the selective packaging of the 8 vRNA segments into virus particles, resulting in the formation of a variety of abnormally packaged virus particles. PB2-vRNA mutants also had reduced replication ability and pathogenicity in mice. Overall, these data demonstrate that the m 5 C residues catalyzed by NSUN2 are required on vRNAs for the proper assembly of infectious viral particles, suggesting the depletion of m 5 C modification as a potential strategy that can be utilized to attenuate IAV strains. Significance Statement Influenza A virus (IAV) infections pose a significant threat to global public health by causing substantial morbidity and mortality. The segmented nature of the IAV genome requires precise regulation of the genomic assembly to produce infectious progeny virus particles. In this study, we demonstrate that m 5 C modification is crucial for the proper assembly of infectious viral particles. The lowered level of m 5 C modifications on vRNAs leads to the generation of defective interfering particles with reduced replication capacity and pathogenicity. Our data shed new light on the selective packaging mechanism of IAV segmented genome and highlight a potential new strategy for attenuating IAV strains by targeting the m 5 C modification machinery.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.