The PRMT5/WDR77 complex restricts hepatitis E virus replication

Author summaryHEV is an underestimated pathogen, causing about 20 million infections worldwide every year and leading to approximately 70,000 deaths. There are no direct-acting antivirals for HEV treatment. Although significant progress has been made about HEV replication, but host factors regulating HEV replication have not been fully characterized. Here, using ORF1 trans-complementation system and HEV replicon harbouring HA-Flag tag in ORF1, we systematically analyse host factors in HEV replication complex in viral replication condition. Specifically, protein arginine methyltransferase 5 (PRMT5)/WDR77 complex was found to be in HEV replication complex and play an inhibitory role in HEV infection among different HEV strain, but not in HCV and SARS-CoV-2 infection. In details, PRMT5/WDR77 complex is able to methylate HEV ORF1 at 458(th) arginine, which is responsible for HEV replication, to repress HEV replication. Consistently, HEV with R458K substitution in ORF1 escape the restriction by PRMT/WDR77, with enhanced replication capability. This work not only provides novel insights into HEV replication and viral-host interaction, but also informs the antiviral strategy against HEV infection. Hepatitis E virus (HEV) is one of the main pathogenic agents of acute hepatitis in the world. The mechanism of HEV replication, especially host factors governing HEV replication is still not clear. Here, using HEV ORF1 trans-complementation cell culture system and HEV replicon system, combining with stable isotope labelling with amino acids in cell culture (SILAC) and mass spectrometry (MS), we aimed to identify the host factors regulating HEV replication. We identified a diversity of host factors associated with HEV ORF1 protein, which were putatively responsible for viral genomic RNA replication, in these two cell culture models. Of note, the protein arginine methyltransferase 5 (PRMT5)/WDR77 complex was identified in both cell culture models as the top hit. Furthermore, we demonstrated that PRMT5 and WDR77 can specifically inhibit HEV replication, but not other viruses such as HCV or SARS-CoV-2, and this inhibition is conserved among different HEV strains and genotypes. Mechanistically, PRMT5/WDR77 can catalyse methylation of ORF1 on its R458, impairing its replicase activity, and virus bearing R458K mutation in ORF1 relieves the restriction of PRMT5/WDR77 accordingly. Taken together, our study promotes more comprehensive understanding of viral infections but also provides therapeutic targets for intervention.