N6-methyladenosine regulates PEDV replication and host gene expression.

Methylation of the N6 position of adenosine (mA) is a widespread RNA modification that is critical for various physiological and pathological processes. Although this modification was also found in the RNA of several viruses almost 40 years ago, its biological functions during viral infection have been elucidated recently. Here, we investigated the effects of viral and host RNA methylation during porcine epidemic diarrhea virus (PEDV) infection. The results demonstrated that the mA modification was abundant in the PEDV genome and the host methyltransferases METTL3 and METTL14 and demethylase FTO were involved in the regulation of viral replication. The knockdown of the methyltransferases increased PEDV replication while silencing the demethylase decreased PEDV output. Moreover, the proteins of the YTHDF family regulated the PEDV replication by affecting the stability of mA-modified viral RNA. In particular, PEDV infection could trigger an increasement of mA in host RNA and decrease the expression of FTO. The mA modification sites in mRNAs and target genes were also altered during PEDV infection. Additionally, part of the host responses to PEDV infection was controlled by mA modification, which could be reversed by the expression of FTO. Taken together, our results identified the role of mA modification in PEDV replication and interactions with the host.