Distinct Roles for Sialoside and Protein Receptors in Coronavirus Infection

Qing, Enya; Hantak, Michael; Perlman, Stanley; Gallagher, Tom

To determine whether the MERS S1A domains operate in the cell fusion process, S1A-Fc proteins (Fig. S5) were added during the assays. Exogenous S1A proteins interfered with hDPP4-independent MERS S-mediated fusion but had no effect on fusion when hDPP4 was present (Fig. 5C ). To determine whether sialic acids operate in the cell fusion process, neuraminidase was added during the assays. Exogenous neuraminidase reduced hDPP4-independent MERS-S-mediated fusion but had no effect on the cell fusion when hDPP4 was present (Fig. S3) . These results further suggest that either of the two S domains, S1A or S1B, can tether S proteins to target cells for subsequent cell-cell fusions, with distinct host receptors for each domain.