SARS-CoV-2 spike protein receptor-binding domain N-glycans facilitate viral internalization in respiratory epithelial cells.

ABSTRACT

N-glycosylation plays an important role in the pathogenesis of viral infections. However, the role of SARS-CoV-2 RBD N-glycosylation in viral entry remains elusive. In this study, we expressed and purified N331 and N343 N-glycosite mutants of SARS-CoV-2 RBD. We found that de-glycosylation at N331 and N343 drastically reduces the RBD binding to ACE2. More importantly, based on qualitative and quantitative virology research methods, we show that the mutation of RBD N-glycosites interfered with SARS-CoV-2 internalization rather than attachment potentially by decreasing RBD binding to the receptors. Also, the double N-glycosites mutant (N331 + N343) showed significantly increased sensitivity against the designated RBD neutralizing antibodies. Taken together, these results suggest that N-glycosylation of SARS-CoV-2 RBD is not only critical for viral internalization into respiratory epithelial cells but also shields the virus from neutralization. It may provide new insights into the biological process of early-stage SARS-CoV-2 infection with potential therapeutic implications.