Protein glycosylation is a post-translational modification involving the enzymatic attachment of complex sugars (glycans). Viral surface proteins are processed in the ER and acquire Nglycosylation, a form of glycosylation that occurs at the amide nitrogen of asparagine residues primarily located in N-X-S/T (X ≠ proline) consensus sequons . Glycosylation is a fundamental process critical for protein folding and function, including the receptor binding and fusion activities of viral surface proteins . Critically, the high density of glycosylation sites on viral surface exposed glycoproteins can shield antigenic sites and help these viruses avoid host immunorecognition . Protein glycosylation in the ER is also critical in assisting productive protein folding by helping to recruit a variety of chaperones that catalyse protein folding and the formation of protein disulfide bonds. Protein chaperones such as the binding immunoglobulin protein (BiP), lectin chaperones calnexin and calreticulin, and protein disulfide isomerases act in concert to assist productive protein folding .