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Article

A Reliable Indirect ELISA Protocol for Detection of Human Antibodies Directed to SARS-CoV-2 NP Protein

1
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, P.O. Box 128442, Jeddah 21362, Saudi Arabia
2
Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, P.O. Box 80324, Jeddah 21589, Saudi Arabia
*
Authors to whom correspondence should be addressed.
Equally contributed to this work.
Academic Editor: Nuno Taveira
Diagnostics 2021, 11(5), 825; https://doi.org/10.3390/diagnostics11050825
Received: 20 April 2021 / Accepted: 30 April 2021 / Published: 2 May 2021
(This article belongs to the Collection Diagnostic Virology)
A few months ago, the availability of a reliable and cost-effective testing capacity for COVID-19 was a concern for many countries. With the emergence and circulation of new SARS-CoV-2 variants, another layer of challenge can be added for COVID-19 testing at both molecular and serological levels. This is particularly important for the available tests principally designed to target the S gene/protein where multiple mutations have been reported. Herein, the SARS-CoV-2 NP recombinant protein was utilized to develop a simple and reliable COVID-19 NP human IgG ELISA. The optimized protocol was validated against a micro-neutralization (MN) assay, in-house S-based ELISA, and commercial chemiluminescence immunoassay (CLIA). The developed assay provides 100% sensitivity, 98.9% specificity, 98.9% agreement, and high overall accuracy with an area under curve equal to 0.9998 ± 0.0002 with a 95% confidence interval of 0.99 to 1.00. The optical density values of positive samples significantly correlated with their corresponding MN titers. The assay specifically detects IgG antibodies to the SARS-CoV-2 NP protein and does not cross-detect IgG to the viral S protein. Moreover, it does not cross-react with antibodies related to other coronaviruses (e.g., the Middle East respiratory syndrome coronavirus or human coronavirus HKU1). The availability of this reliable COVID-19 NP IgG ELISA protocol is highly valuable for its diagnostic and epidemiological applications. View Full-Text
Keywords: COVID-19; SARS-CoV-2; ELISA; serology; seroprevalence; nucleocapsid COVID-19; SARS-CoV-2; ELISA; serology; seroprevalence; nucleocapsid
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MDPI and ACS Style

Faizo, A.A.; Alandijany, T.A.; Abbas, A.T.; Sohrab, S.S.; El-Kafrawy, S.A.; Tolah, A.M.; Hassan, A.M.; Azhar, E.I. A Reliable Indirect ELISA Protocol for Detection of Human Antibodies Directed to SARS-CoV-2 NP Protein. Diagnostics 2021, 11, 825. https://doi.org/10.3390/diagnostics11050825

AMA Style

Faizo AA, Alandijany TA, Abbas AT, Sohrab SS, El-Kafrawy SA, Tolah AM, Hassan AM, Azhar EI. A Reliable Indirect ELISA Protocol for Detection of Human Antibodies Directed to SARS-CoV-2 NP Protein. Diagnostics. 2021; 11(5):825. https://doi.org/10.3390/diagnostics11050825

Chicago/Turabian Style

Faizo, Arwa A., Thamir A. Alandijany, Ayman T. Abbas, Sayed S. Sohrab, Sherif A. El-Kafrawy, Ahmed M. Tolah, Ahmed M. Hassan, and Esam I. Azhar. 2021. "A Reliable Indirect ELISA Protocol for Detection of Human Antibodies Directed to SARS-CoV-2 NP Protein" Diagnostics 11, no. 5: 825. https://doi.org/10.3390/diagnostics11050825

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