Sialic acid functions in enterovirus 70 binding and infection

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Viral infection initiates through interactions between viruses and host cell receptors.
• Enterovirus 70 (EV70), a cause of acute hemorrhagic conjunctivitis, utilizes decay-accelerating factor (DAF/CD55) as an attachment receptor.
• Previous studies indicated sialic acid's role in EV70 attachment to erythrocytes.

Purpose of the Study:

• To investigate the role of cell surface sialic acid in EV70 binding to nucleated cells.
• To determine if sialic acid residues on DAF/CD55 are essential for EV70 attachment.
• To elucidate the contribution of glycosylation (N-linked vs. O-linked) to EV70 binding.

Main Methods:

• Site-directed mutagenesis of DAF/CD55 to alter glycosylation sites.
• Construction of chimeric receptor proteins involving DAF/CD55 and HLA-B44.
• Treatment of cells with glycosylation inhibitors.
• Assessment of EV70 binding to modified cells.

Main Results:

• Cell surface sialic acid is essential for EV70 binding to nucleated cells and productive infection.
• DAF/CD55 glycosylation status did not affect EV70 binding, excluding its sialic acid residues as the primary binding site.
• N-linked glycosylation is not required for EV70 binding.
• O-linked glycosylation appears to be important for EV70 attachment to host cells.

Conclusions:

• Cell surface sialic acid is a critical factor for EV70 infection of nucleated cells.
• While DAF/CD55 is an EV70 receptor, its sialic acid residues are not the primary attachment point.
• The findings suggest the existence of an additional, sialylated cellular factor involved in EV70 binding.
• O-linked glycosylation plays a significant role in mediating EV70 attachment to host cells.