Nucleocapsid Specific Diagnostics for the Detection of Divergent SARS-CoV-2 Variants

• DOI: 10.3389/fimmu.2022.926262
• Publication Date: 2022-06-10T05:38:49Z
• Authors: Ariel Isaacs; Alberto A. Amarilla; Julio Aguado; Naphak Modhiran; Eduardo A. Albornoz; Alireza A. Baradar; Christopher L. D....; Jovin J. Y. Choo; Adi Idris; Aroon Supramaniam; Nigel A. J. McMillan; David A. Muller; Paul R. Young; Trent M. Woodruff; Ernst J. Wolvetang; Keith J. Chappell; Daniel Watterson
• Keywords: 0301 basic medicine; 570; Immunology; nucleocapsid; 610; 03 medical and health sciences; diagnostics; Genetics; Humans; immunofluorescence; Nucleocapsid; Pandemics; Science & Technology; SARS-CoV-2; Antibodies, Monoclonal; COVID-19; RC581-607; Nucleocapsid Proteins; Single-Domain Antibodies; immunoplaque assay; Antibodies, Neutralizing; 3. Good health; immunoassays; nanobody; Biochemistry and cell biology; Immunologic diseases. Allergy; Life Sciences & Biomedicine

Since the start of the COVID-19 pandemic, multiple waves of SARS-CoV-2 variants have emerged. Of particular concern is the omicron variant, which harbors 28 mutations in the spike glycoprotein receptor binding and N-terminal domains relative to the ancestral strain. The high mutability of SARS-CoV-2 therefore poses significant hurdles for development of universal assays that rely on spike-specific immune detection. To address this, more conserved viral antigens need to be targeted. In this work, we comprehensively demonstrate the use of nucleocapsid (N)-specific detection across several assays using previously described nanobodies C2 and E2. We show that these nanobodies are highly sensitive and can detect divergent SARS-CoV-2 ancestral, delta and omicron variants across several assays. By comparison, spike-specific antibodies S309 and CR3022 only disparately detect SARS-CoV-2 variant targets. As such, we conclude that N-specific detection could provide a standardized universal target for detection of current and emerging SARS-CoV-2 variants of concern.