N-Glycan Modification in Covid-19 Pathophysiology: In vitro Structural Changes with Limited Functional Effects

Area of Science:

• Virology
• Glycobiology
• Drug Discovery

Background:

• Congenital disorders of glycosylation (CDG) can alter viral susceptibility.
• Mannosyl-oligosaccharide glucosidase (MOGS) deficiency causes CDG with in vitro resistance to enveloped viruses.
• Investigating FDA-approved drugs like miglustat for antiviral potential against SARS-CoV-2 is crucial.

Purpose of the Study:

• To assess the in vitro antiviral activity of miglustat against SARS-CoV-2.
• To evaluate the effect of miglustat on N-glycan modification of SARS-CoV-2 spike (S) and ACE2 glycoproteins.
• To determine if miglustat impacts S-ACE2 binding, cell-to-cell fusion, or immune response.

Main Methods:

• Overexpression of SARS-CoV-2 S and ACE2 glycoproteins.
• N-glycan modification analysis following miglustat treatment.
• Immunoprecipitation to assess S-ACE2 binding.
• Immunofluorescence for cell-to-cell fusion assays.
• Cytokine release measurement from peripheral blood mononuclear cells (PBMCs).

Main Results:

• Miglustat specifically modified N-glycans on both SARS-CoV-2 S and ACE2 in the overexpression system.
• N-glycan modifications did not affect the binding affinity between S and ACE2.
• Miglustat did not inhibit SARS-CoV-2 S-driven cell-to-cell fusion, a marker of viral cytopathic effect.
• Miglustat treatment showed no significant impact on cytokine production by PBMCs stimulated with SARS-CoV-2 S.

Conclusions:

• Miglustat alters N-glycans of SARS-CoV-2 S and ACE2 but does not inhibit key viral-host interactions.
• The functional integrity of these glycoproteins is maintained despite glycan changes induced by miglustat.
• Miglustat is unlikely to be an effective therapeutic agent for altering the course of COVID-19.