Performance of the rapid high-throughput automated electrochemiluminescence immunoassay targeting total antibodies to the SARS-CoV-2 spike protein receptor binding domain in comparison to the neutralization assay

Resman Rus, Katarina (author), Korva, Miša (author), Knap, Nataša (author), Avšič-Županc, Tatjana (author), Poljak, Mario (author)

Background: Neutralization tests (NT) are the gold standard for detecting and quantifying anti-SARS-CoV-2 neutralizing antibodies (NAb), but their complexity restricts them to research settings or reference laboratories. Antibodies against S protein receptor binding domain (RBD) have been shown to confer a neutralizing activity against SARS-CoV-2. Assays quantitatively measuring anti-S1-RBD-SARS-CoV-2 antibodies could be of great value for NAb screening of potential donors for convalescent-phase plasma therapy, assessing natural or vaccine-induced immunity, stratifying individuals for vaccine receipt, and documenting vaccine response. Methods: Elecsys Anti-SARS-CoV-2 S (Elecsys-S), a high-throughput automated electrochemiluminescence double-antigen sandwich immunoassay for quantitative measurement of pan-anti-S1-RBD-SARS-CoV-2 antibodies, was evaluated against NT on 357 patients with PCR-confirmed SARS-CoV-2 infection. NT was performed in a BSL-3 laboratory using a Slovenian SARS-CoV-2 isolate; the NT titer ≥1:20 was considered positive. Results: Elecsys-S detected pan-anti-S1-RBD-SARS-CoV-2 antibodies in 352/357 (98.6 %) samples. NAb were identified by NT in 257/357 (72 %) samples. The Elecsys-S/NT agreement was moderate (Cohen’s kappa 0.56). High NT titer antibodies (≥1:160) were detected in 106/357 (30 %) samples. Elecsys-S’s pan-anti-S1-RBD-SARS-CoV-2 antibody concentrations correlated with individual NT titer categories (the lowest concentrations were identified in NT-negative samples and the highest in samples with NT titer 1:1,280), and the Elecsys-S cutoff value for reasonable prediction of NAb generated after natural infection was established (133 BAU/mL). Conclusion: Although NT should remain the gold standard for assessing candidates for convalescent-phase plasma donors, selected commercial anti-SARS-CoV-2 assays with optimized cutoff, like Elecsys-S, could be used for rapid, automated, and large-scale screening of individuals with clinically relevant NAb levels as suitable donors.

• Language: English
• Keywords: SARS-CoV-2, immunoassay, antibody, electrochemiluminescence, neutralization
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: MF - Faculty of Medicine
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 4 str.
• Numbering: Vol. 139, art. 104820
• PID: 20.500.12556/RUL-138707
• UDC: 616.9
• ISSN on article: 1873-5967
• DOI: 10.1016/j.jcv.2021.104820
• COBISS.SI-ID: 61792771
• Publication date in RUL: 10.08.2022

Record is a part of a journal

• Title: Journal of clinical virology
• Publisher: Elsevier
• ISSN: 1873-5967
• COBISS.SI-ID: 23214341

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: SARS-CoV-2, imunski test, protitelesa