Synthetic Homogeneous Glycoforms of the SARS-CoV-2 Spike Receptor-Binding Domain Reveals Different Binding Profiles of Monoclonal Antibodies

SARS-CoV-2 attaches to its host receptor, angiotensin-converting enzyme 2 (ACE2), via the receptor-binding domain (RBD) of the spike protein. The RBD glycoprotein is a critical target for the development of neutralizing antibodies and vaccines against SARS-CoV-2. However, the high heterogeneity of RBD glycoforms may lead to an incomplete neutralization effect and impact the immunogenic integrity of RBD-based vaccines. Investigating the role of different carbohydrate domains is of paramount importance. Unfortunately, there is no viable method for preparing RBD glycoproteins with structurally defined glycans. Herein we describe a highly efficient and scalable strategy for the preparation of six glycosylated RBDs bearing defined structure glycoforms at T323, N331, and N343. A combination of modern oligosaccharide, peptide synthesis and recombinant protein engineering provides a robust route to decipher carbohydrate structure-function relationships.

Automated summary

Investigating the role of carbohydrate domains in RBD glycoproteins is crucial for the development of neutralizing antibodies and vaccines against SARS-CoV-2, but the high heterogeneity of glycoforms may result in incomplete neutralization effects. This study presents an efficient and scalable strategy for preparing six glycosylated RBDs with defined structure glycoforms, providing insights into the structure-function relationships of carbohydrates.