Impact of glycosylation and length of RBD of SARS-CoV-2 S protein on the immunogenicity of RBD protein vaccines

Abstract

Abstract: Objective To analyze the impact of deglycosylation and length of RBD of SARS-CoV-2 S protein on the immunogenicity. Methods Based on the RBD of the SARS-CoV-2 S protein, three N-glycosylated residues (N331, N343, N360) in the 220 amino acid RBD (aa.331-550) were respectively mutated, and trimerization domains were fused at the C-terminus of resulted peptides. The resulted deglycosylated trimer proteins (RBDT-N1, RBDT-N2, RBDT-N3) were expressed in baculovirus-insect cell expression system. The wild-type control of deglycosylated proteins (RBDT) and RBDST (aa.319-591) with a length of 273 amino acids were also constructed. The expression levels were analyzed by Western blot. Proteins were purified by affinity chromatography. Mice were immunized, and the sera were subjected to analysis of RBD-specific IgG and neutralizing antibodies against SARS-CoV-2 pseudovirus. Results Deglycosylation increased the expression level of RBD trimers in insect cells. RBDT and three deglycosylated proteins (RBDT-N1, RBDT-N2, RBDT-N3) induced similar level of RBD-specific IgG and SARS-CoV-2 pseudovirus neutralization titers. RBDST induced high titers of RBD-specific IgG and neutralizing antibodies, which were both significantly higher than that induced by RBDT (P＜0.05,P＜0.01). Conclusions The results suggest that removing the N-glycosylation residues of RBD and extending the RBD flanking sequence are beneficial to increase the expression and immunogenicity of the RBD protein vaccine. The research provides a useful reference for the development strategy of RBD-based SARS-CoV-2 vaccines.

Key words: SARS-CoV-2, receptor binding domain, glycosylation

CLC Number:

R392

ZHANG Ting, WANG Zhi-rong, XU Xue-mei. Impact of glycosylation and length of RBD of SARS-CoV-2 S protein on the immunogenicity of RBD protein vaccines[J]. Basic & Clinical Medicine, 2020, 40(12): 1645-1650.

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