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  • Linear B-cell epitopes in the spike and nucleocapsid proteins as markers of SARS-CoV-2 exposure and disease severity.

Linear B-cell epitopes in the spike and nucleocapsid proteins as markers of SARS-CoV-2 exposure and disease severity.

EBioMedicine (2020-07-28)
Siti Naqiah Amrun, Cheryl Yi-Pin Lee, Bernett Lee, Siew-Wai Fong, Barnaby Edward Young, Rhonda Sin-Ling Chee, Nicholas Kim-Wah Yeo, Anthony Torres-Ruesta, Guillaume Carissimo, Chek Meng Poh, Zi Wei Chang, Matthew Zirui Tay, Yi-Hao Chan, Mark I-Cheng Chen, Jenny Guek-Hong Low, Paul A Tambyah, Shirin Kalimuddin, Surinder Pada, Seow-Yen Tan, Louisa Jin Sun, Yee-Sin Leo, David C Lye, Laurent Renia, Lisa F P Ng
ABSTRACT

Given the unceasing worldwide surge in COVID-19 cases, there is an imperative need to develop highly specific and sensitive serology assays to define exposure to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Pooled plasma samples from PCR positive COVID-19 patients were used to identify linear B-cell epitopes from a SARS-CoV-2 peptide library of spike (S), envelope (E), membrane (M), and nucleocapsid (N) structural proteins by peptide-based ELISA. Hit epitopes were further validated with 79 COVID-19 patients with different disease severity status, 13 seasonal human CoV, 20 recovered SARS patients and 22 healthy donors. Four immunodominant epitopes, S14P5, S20P2, S21P2 and N4P5, were identified on the S and N viral proteins. IgG responses to all identified epitopes displayed a strong detection profile, with N4P5 achieving the highest level of specificity (100%) and sensitivity (>96%) against SARS-CoV-2. Furthermore, the magnitude of IgG responses to S14P5, S21P2 and N4P5 were strongly associated with disease severity. IgG responses to the peptide epitopes can serve as useful indicators for the degree of immunopathology in COVID-19 patients, and function as higly specific and sensitive sero-immunosurveillance tools for recent or past SARS-CoV-2 infections. The flexibility of these epitopes to be used alone or in combination will allow for the development of improved point-of-care-tests (POCTs). Biomedical Research Council (BMRC), the A*ccelerate GAP-funded project (ACCL/19-GAP064-R20H-H) from Agency of Science, Technology and Research (A*STAR), and National Medical Research Council (NMRC) COVID-19 Research fund (COVID19RF-001) and CCGSFPOR20002. ATR is supported by the Singapore International Graduate Award (SINGA), A*STAR.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Poly(vinyl alcohol), Mw 89,000-98,000, 99+% hydrolyzed
Sigma-Aldrich
3,3′,5,5′-Tetramethylbenzidine (TMB) Liquid Substrate System, peroxidase substrate
Sigma-Aldrich
Dimethyl sulfoxide, Hybri-Max, sterile-filtered, BioReagent, suitable for hybridoma, ≥99.7%