Nanoluciferase complementation-based bioreporter reveals the importance of N-linked glycosylation of SARS-CoV-2 Spike for viral entry

Azad, Taha; Singaravelu, Ragunath; Taha, Zaid; Jamieson, Taylor R.; Boulton, Stephen; Crupi, Mathieu J.F.; Martin, Nikolas T.; Brown, Emily E.F.; Poutou, Joanna; Ghahremani, Mina; Pelin, Adrian; Nouri, Kazem; Rezaei, Reza; Marshall, Christopher Boyd; Enomoto, Masahiro; Arulanandam, Rozanne; Alluqmani, Nouf; Samson, Reuben; Gingras, Anne-Claude; Cameron, D. William; Greer, Peter A.; Ilkow, Carolina S.; Diallo, Jean-Simon; Bell, John C.

The ongoing COVID-19 pandemic has highlighted the immediate need for the development of antiviral therapeutics targeting different stages of the SARS-CoV-2 lifecycle. We developed a bioluminescence-based bioreporter to interrogate the interaction between the SARS-CoV-2 viral spike protein and its host entry receptor, angiotensin-converting enzyme 2 (ACE2)1-3. The bioreporter assay is based on a Nanoluciferase complementation reporter, composed of two subunits, Large BiT and Small BiT, fused to the spike receptor-binding domain (RBD) of the SARS-CoV-2 S protein and ACE2 ectodomain, respectively. Using this bioreporter, we uncovered critical host and viral determinants of the interaction, including a role for glycosylation of asparagine residues within the RBD in mediating successful viral entry. We also demonstrate the importance of N-linked glycosylation to RBD’s antigenicity and immunogenicity. Our study demonstrates the versatility of our bioreporter in mapping key residues mediating viral entry as well as screening inhibitors of the ACE2-RBD interaction. Our findings point towards targeting RBD glycosylation for therapeutic and vaccine strategies against SARS-CoV-2.