In 2014, we reported two siblings with a rare
congenital disorder of glycosylation due to mutations in
mannosyl-oligosaccharide glucosidase (MOGS). The
glycan alteration derived from this disease resulted in an in vitro infection resistance to particular enveloped, N-glycosylation-dependent viruses as
influenza and HIV. As part of the global effort to find safe and effective
antiviral therapies for
Covid-19, we assessed the in vitro activity of the FDA-approved α-
glucosidase inhibitor
miglustat against SARS-CoV-2. Expression plasmids encoding SARS-CoV-2 spike (S) and human ACE2
glycoproteins (GP) were tested to evaluate N-
glycan modifications induced by α-
glucosidase inhibition. Immunoprecipitation was used to assess binding between these two GP. Cell-to-cell fusion was assessed by immunofluorescence of cocultures of SARS-CoV-2 S and ACE2-expressing cells.
Miglustat effect on immune response was tested by measuring
cytokine release from PBMC exposed to purified SARS-CoV-2 S. In our overexpression system,
miglustat successfully and specifically modified N-
glycans in both SARS-CoV-2 S and its main receptor ACE2. Binding between these two GP was not affected by
glycan modifications. A
surrogate marker for viral cytopathic effect, measured as receptor-dependent SARS-CoV-2 S-driven cell-to-cell fusion, was not disrupted by
miglustat treatment. This observation was further confirmed in MOGS-null transfected cells.
Miglustat produced no statistically significant effects on
cytokine production following SARS-CoV-2 S
glycoprotein stimulation of PBMC. Our work shows that despite clear N-
glycan alteration in the presence of
miglustat, the functions of the Covid-19-related
glycoproteins studied were not affected, making it unlikely that
miglustat can change the natural course of the disease.