N6-Methyladenosine Positively Regulates Coxsackievirus B3 Replication.

Enteroviruses such as coxsackievirus B3 are identified as a common cause of viral myocarditis, but the potential mechanism of its replication and pathogenesis are largely unknown. The genomes of a variety of viruses contain N6-methyladenosine (mA), which plays important roles in virus replication. Here, by using the online bioinformatics tools SRAMP and indirect immunofluorescence assay (IFA), we predict that the CVB3 genome contains mA sites and found that CVB3 infection could alter the expression and cellular localization of mA-related proteins. Moreover, we found that 3-deazaadenosine (3-DAA), an mA modification inhibitor, significantly decreased CVB3 replication. We also observed that the mA methyltransferases methyltransferase-like protein 3 (METTL3) and METTL14 play positive roles in CVB3 replication, whereas mA demethylases fat mass and obesity-associated protein (FTO) or AlkB homolog 5 (ALKBH5) have opposite effects. Knockdown of the mA binding proteins YTH domain family protein 1 (YTHDF1), YTHDF2 and YTHDF3 strikingly decreased CVB3 replication. Finally, the mA site mutation in the CVB3 genome decreased the replication of CVB3 compared with that in the CVB3 wild-type (WT) strain. Taken together, our results demonstrated that CVB3 could exploit mA modification to promote viral replication, which provides new insights into the mechanism of the interaction between CVB3 and the host.