Spike vs nucleocapsid SARS-CoV-2 antigen detection: application in nasopharyngeal swab specimens

• Published in: Analytical and bioanalytical chemistry 2021-05, Vol.413 (13), p.3501-3510
• Main Authors: Barlev-Gross, Moria, Weiss, Shay, Ben-Shmuel, Amir, Sittner, Assa, Eden, Keren, Mazuz, Noam, Glinert, Itai, Bar-David, Elad, Puni, Reut, Amit, Sharon, Kriger, Or, Schuster, Ofir, Alcalay, Ron, Makdasi, Efi, Epstein, Eyal, Noy-Porat, Tal, Rosenfeld, Ronit, Achdout, Hagit, Mazor, Ohad, Israely, Tomer, Levy, Haim, Mechaly, Adva
• Format: Article
• Language: English
• Subjects: Analysis; Analytical Chemistry; Antigens; Assaying; Biochemistry; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Commercialization; Coronavirus Nucleocapsid Proteins - analysis; Coronaviruses; COVID-19; COVID-19 - diagnosis; COVID-19 Serological Testing - methods; Enzyme-linked immunosorbent assay; Enzyme-Linked Immunosorbent Assay - methods; Epitopes; Fluorescence; Food Science; Humans; Laboratory Medicine; Methods; Monitoring/Environmental Analysis; Monoclonal antibodies; Nucleocapsids; Phosphoproteins - analysis; Polymerase chain reaction; Public health; Research Paper; SARS-CoV-2 - isolation & purification; Sensitivity; Sensitivity and Specificity; Severe acute respiratory syndrome coronavirus 2; Specimen Handling; Spike Glycoprotein, Coronavirus - analysis; Spikes
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-021-03298-4

Public health experts emphasize the need for quick, point-of-care SARS-CoV-2 detection as an effective strategy for controlling virus spread. To this end, many “antigen” detection devices were developed and commercialized. These devices are mostly based on detecting SARS-CoV-2’s nucleocapsid protein. Recently, alerts issued by both the FDA and the CDC raised concerns regarding the devices’ tendency to exhibit false positive results. In this work, we developed a novel alternative spike-based antigen assay, comprising four high-affinity, specific monoclonal antibodies, directed against different epitopes on the spike’s S1 subunit. The assay’s performance was evaluated for COVID-19 detection from nasopharyngeal swabs, compared to an in-house nucleocapsid-based assay, composed of novel antibodies directed against the nucleocapsid. Detection of COVID-19 was carried out in a cohort of 284 qRT-PCR positive and negative nasopharyngeal swab samples. The time resolved fluorescence (TRF) ELISA spike assay displayed very high specificity (99%) accompanied with a somewhat lower sensitivity (66% for Ct