Disrupted glycosylphosphatidylinositol anchoring induces ER stress and restricts enterovirus infection.

Many positive-sense RNA viruses, including viruses from the Picornaviridae, Coronaviridae and Flaviviridae family, exploit endoplasmic reticulum (ER)-derived membrane structures as sites of genome replication. Here we use a pooled CRISPR genetic screening strategy to identify glycosylphosphatidylinositol (GPI) anchor biosynthesis and transfer genes as host factors for echovirus 7 infection. In addition to supporting the biogenesis of CD55, which is a GPI anchor protein and an entry factor for some echoviruses, the GPI anchor synthesis machinery also supports several other enterovirus infections by enhancing viral replication and replication organelle biogenesis. Disruption of GPI anchor transfer machinery compromises ER integrity and causes ER stress. Consistent with these findings, ER-resident sensor, inositol-requiring protein 1α (IRE1α) is activated and regulated IRE1-dependent decay of mRNA (RIDD) is detected to reduce ER stress. Interestingly, enterovirus viral RNA, but not Hepatitis C Virus RNA, is degraded during this process due to specific sequences in the Untranslated Region (UTR). This study revealed novel links between GPI anchoring, ER stress and enterovirus infection, and illuminates new host targets for antiviral therapy.