Identification of an N6-methyladenosine-mediated positive feedback loop that promotes Epstein-Barr virus infection.

N6-methyladenosine (mA) is among the most abundant mRNA modifications, particularly in eukaryotes, and is found in mammals, plants, and even some viruses. Although essential for the regulation of many biological processes, the exact role of mA modification in virus-host interaction remains largely unknown. Here, using mA -immunoprecipitation and sequencing, we find that Epstein-Barr virus (EBV) infection decreases the mA modification of transcriptional factor KLF4 mRNA and subsequently increases its protein level. Mechanistically, EBV immediate-early protein BZLF1 interacts with the promoter of mA methyltransferase METTL3, inhibiting its expression. Subsequently, the decrease of METTL3 reduces the level of KLF4 mRNA mA modification, preventing its decay by the mA reader protein YTHDF2. As a result, KLF4 protein level is upregulated and, in turn, promotes EBV infection of nasopharyngeal epithelial cells. Thus, our results suggest the existence of a positive feedback loop formed between EBV and host molecules via cellular mRNA mA levels, and this feedback loop acts to facilitate viral infection. This mechanism contains multiple potential targets for controlling viral infectious diseases.