Dual ELISA using SARS-CoV-2 nucleocapsid protein produced in E. coli and CHO cells reveals epitope masking by N-glycosylation

Airi Rump; Robert Risti; Mai-Ly Kristal; Jekaterina Reut; Vitali Syritski; Aivar Lookene; Sirje Ruutel Boudinot

doi:10.1016/j.bbrc.2020.11.060

Dual ELISA using SARS-CoV-2 nucleocapsid protein produced in E. coli and CHO cells reveals epitope masking by N-glycosylation

Biochem Biophys Res Commun. 2021 Jan 1:534:457-460. doi: 10.1016/j.bbrc.2020.11.060. Epub 2020 Nov 20.

Authors

Airi Rump¹, Robert Risti², Mai-Ly Kristal³, Jekaterina Reut⁴, Vitali Syritski⁵, Aivar Lookene⁶, Sirje Ruutel Boudinot⁷

Affiliations

¹ Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: airirump1@gmail.com.
² Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: robert.risti@taltech.ee.
³ Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: mlykristal@gmail.com.
⁴ Department of Materials and Environmental Technology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: jekaterina.reut@taltech.ee.
⁵ Department of Materials and Environmental Technology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: vitali.syritski@taltech.ee.
⁶ Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: aivar.lookene@taltech.ee.
⁷ Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, 12618, Estonia. Electronic address: sirje.boudinot@gmail.com.

Abstract

Spike and nucleocapsid proteins of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2-SP, SARS-CoV-2-NP) are the main immunogenic targets for antibodies. We herein demonstrate that the glycosylation of SARS-CoV-2-NP masks some of its antibody epitopes. In many cases, this can lead to false-negative serological tests. Deglycosylation of SARS-CoV-2-NP significantly increased the number of positive tests. The glycosylation pattern analysis of this protein revealed that the putative N-linked glycosylation sites, at the amino acid positions 48 and 270, co-located with two of the main immunodominant B cell epitopes.

Keywords: Glycosylation; Nucleocapsid protein (NP); SARS-CoV-2.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
CHO Cells
Cricetinae
Cricetulus
Enzyme-Linked Immunosorbent Assay / methods*
Epitopes / genetics
Epitopes / immunology*
Epitopes / metabolism
Escherichia coli / genetics
Glycosylation
Humans
Recombinant Proteins / immunology*
Recombinant Proteins / metabolism
Spike Glycoprotein, Coronavirus / genetics
Spike Glycoprotein, Coronavirus / immunology*
Spike Glycoprotein, Coronavirus / metabolism

Substances

Epitopes
Recombinant Proteins
Spike Glycoprotein, Coronavirus
spike protein, SARS-CoV-2