Wisteria floribunda agglutinin enhances Zaire ebolavirus entry through interactions at specific N-linked glycosylation sites on the virus glycoprotein complex

Entry of <i>Zaire</i> e<i>bolavirus</i> (EBOV) into a host cell is a complex process requiring interactions between the viral glycoproteins (GPs) and cellular factors. These entry factors are cell-specific and can include cell surface lectins and phosphatidylserine receptors. Niemann-Pick type C1 is critical to the late stage of the entry process. Entry has been demonstrated to be enhanced by interactions between the virion and surface-expressed lectins, which interact with carbohydrate moieties attached to the GP. In addition, soluble lectins, including mannose-binding lectin, can enhance entry <i>in vitro</i>. However, the mechanism of lectin-mediated enhancement remains to be defined. This study investigated the possibility that plant lectins, <i>Wisteria floribunda</i> agglutinin (WFA), soybean agglutinin (SBA) and <i>Galanthus nivalis</i> agglutinin (GNA), which possess different carbohydrate-binding specificities, influence EBOV entry. WFA was observed to potently enhance entry of lentiviral pseudotype viruses (PVs) expressing the GP of three <i>Ebolavirus</i> species [Zaire, Sudan (<i>Sudan ebolavirus</i>) and Reston (<i>Reston ebolavirus</i>)], with the greatest impact on EBOV. SBA had a modest enhancing effect on entry that was specific to EBOV, whilst GNA had no impact on the entry of any of the <i>Ebolavirus</i> species. None of the lectins enhanced the entry of control PVs expressing the surface proteins of other RNA viruses tested. WFA was demonstrated to bind directly with the EBOV-GP via the glycans, and mutational analysis implicated N²³⁸ as contributing to the interaction. Furthermore, enhancement was observed in both human and bat cell lines, indicating a highly conserved mechanism of action. We conclude that the binding of WFA to EBOV-GP through interactions including the glycan at N²³⁸ results in GP alterations that enhance entry, providing evidence of a mechanism for lectin-mediated virus entry enhancement. Targeting lectin-ligand interactions presents a potential strategy for restricting <i>Ebolavirus</i> entry.