Site-specific analysis of the SARS-CoV-2 glycan shield

Yasunori Watanabe; Joel D. Allen; Daniel Wrapp; Jason S. McLellan; Max Crispin

Here, we apply mass spectrometry to understand both the site-specific N-linked glycan composition and the degree of sequon occupancy on a soluble, native-like SARS-CoV-2 S protein. The native-like folding of trimeric recombinant material has been recently revealed by detailed structural analysis by cryo-electron microscopy 18, 19 . We have previously validated our glycopeptide analysis methodology and applied this approach to the study of a range of other viral glycoprotein immunogens 4,20-23 , which enables cross-viral comparisons of glycosylation to be made. We report here the site-specific glycosylation at each of the 22 N-linked glycan sites found on the SARS-CoV-2 S protomer. As observed on other viral glycoproteins, there is an elevation in oligomannose-and hybrid-type glycans compared to host-derived glycoproteins, although compared to many other viruses there are still a large population of complex-type glycans displayed across the trimer surface. We also report that for each of the 22 glycan sites the occupancy is nearly fully complete, which means that any epitopes shielded from the . CC-BY 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/2020.03.26.010322 doi: bioRxiv preprint immune system on the virus will also likely be shielded on the immunogen. Site-specific glycan analysis of SARS-CoV-2 immunogens will help guide vaccine design and manufacturing.