Glycosylation in COVID-19

The role of glycosylation (N-Linked & O-Linked) in viruses still remains an active area of research. Many viral glycoproteins are glycosylated. These virus glycoproteins play the biggest role in attaching to host cell receptors and replicating massively. Virologists now want to understand the patterns of glycosylation, the exact role of attached glycans on viral proteins, and the mechanism of glycosylation in order to make a conclusion regarding the significance of glycosylation on viral behaviors. Click here to learn more about the role of glycosylation on viral glycoproteins.

The Spike Protein (S) of all Coronaviruses are heavily glycosylated with N-Linked Glycans. Unlike typical Coronaviruses, the novel SARS-CoV-2 has a new furin cleavage site (has not been observed in other Lineage B betacoronaviruses) in its S-Protein which contains some predicted O-Linked Glycans. The role of the predicted O-Linked Glycans on the S-Protein of COVID-19 remains unclear. However, given that several viruses, pathogenic organisms, and tumors utilize glycan residues to evade the host's immune responses, the predicted O-Linked Glycans on the S-Protein of COVID-19 could function as a 'mucin-like domain' that blocks against epitopes. Glycosylation is an ongoing area of research because scientists still do not know its impact on viral behavior. This further poses a question: To what extent does glycosylation play a role in influencing an organism's immune system and body cells?

Sources (all of above information):

• Sugrue R.J. (2007) Viruses and Glycosylation. In: Sugrue R.J. (eds) Glycovirology Protocols. Methods in Molecular Biology, vol 379. Humana Press

• Andersen, K.G., Rambaut, A., Lipkin, W.I. et al. The proximal origin of SARS-CoV-2. Nat Med (2020). https://doi.org/10.1038/s41591-020-0820-9.