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

• DOI: 10.1007/s00216-021-03298-4
• Publication Date: 2021-03-25T22:57:59Z
• Authors: Moria Barlev-Gross; Shay Weiss; Amir Ben-Shmuel; Assa Sittner; Keren Eden; Noam Mazuz; Itai Glinert; Elad Bar-David; Reut Puni; Sharon Amit; Or Kriger; Ofir Schuster; Ron Alcalay; Efi Makdasi; Eyal Epstein; Tal Noy-Porat; Ronit Rosenfeld; Hagit Achdout; Ohad Mazor; Tomer Israely; Haim Levy; Adva Mechaly
• Keywords: 2019-20 coronavirus outbreak; Coronavirus

Public health experts emphasize the need for quick, point-of-care SARS-CoV-2 detection as an effective strategy controlling virus spread. To this end, many "antigen" devices were developed and commercialized. These are mostly based on detecting SARS-CoV-2's nucleocapsid protein. Recently, alerts issued by both FDA CDC raised concerns regarding devices' tendency to exhibit false positive results. In work, we a novel alternative spike-based antigen assay, comprising four high-affinity, specific monoclonal antibodies, directed against different epitopes spike's S1 subunit. The assay's performance was evaluated COVID-19 from nasopharyngeal swabs, compared in-house nucleocapsid-based composed of antibodies nucleocapsid. Detection carried out in cohort 284 qRT-PCR negative swab samples. time resolved fluorescence (TRF) ELISA spike assay displayed very high specificity (99%) accompanied with somewhat lower sensitivity (66% Ct < 25), which more sensitive (85% 25) while less (87% specificity). Despite being outperformed qRT-PCR, suggest that there is room such tests clinical setting, cheap rapid pre-screening tools. Our results further when applying detection, one must consider its intended application (sensitivity vs specificity), taking into consideration might not be optimal target. regard, propose combination antigens contribute validity