Human GII.4 norovirus VLP induces membrane invaginations on giant unilamellar vesicles containing secretor gene dependent α1,2-fucosylated glycosphingolipids.

Norovirus is a non-enveloped virus causing acute gastroenteritis. For human norovirus, no simple cell culture system is available and consequently knowledge on cellular entry of the virus is limited. The virus binds to ABH histo-blood group glycans on glycoproteins and glycosphingolipids. Non-secretors, characterized by the lack of ABH histo-blood group glycans in the gastrointestinal tract, are resistant to most norovirus infections, suggesting that these glycans may be part of the viral receptor. Recent studies have shown that polyomavirus enters the cell via membrane invaginations induced by the multivalent binding of the virus to receptor glycosphingolipids. In this study, we have investigated whether norovirus has the ability to induce membrane invaginations on giant unilamellar vesicles (GUVs) containing purified glycosphingolipids. First, we characterized the glycosphingolipid binding pattern of VLPs from the Dijon strain (genogroup II.4), using thin-layer chromatography. The VLP recognized the ABH active glycosphingolipids H type 1, Lewis b, B type 1, A type 1 and A Lewis b, but not lactotetraosylceramide or Lewis a, typically found in non-secretors. The binding pattern to glycosphingolipids incorporated into GUVs was in full agreement with the thin-layer chromatography experiments. Upon binding to the vesicles, the VLPs formed highly mobile clusters on the surface of the GUVs. VLP containing tubular invaginations were seen on the GUVs containing glycosphingolipids recognized by the VLP. In conclusion, this study suggests that human norovirus has the ability to induce membrane curvature by binding to and clustering glycosphingolipids, which may reflect the first step in cellular entry of the virus.