Monoclonal antibodies for the S2 subunit of spike of SARS-CoV-1 cross-react with the newly-emerged SARS-CoV-2

Abstract

Background: A novel coronavirus, SARS-CoV-2, which emerged at the end of 2019 and causes COVID-19, has resulted in worldwide human infections. While genetically distinct, SARS-CoV-1, the aetiological agent responsible for an outbreak of severe acute respiratory syndrome (SARS) in 2002-2003, utilises the same host cell receptor as SARS-CoV-2 for entry: angiotensin-converting enzyme 2 (ACE2). Parts of the SARS-CoV-1 spike glycoprotein (S protein), which interacts with ACE2, appear conserved in SARS-CoV-2. Aim: The cross-reactivity with SARS-CoV-2 of monoclonal antibodies (mAbs) previously generated against the S protein of SARS-CoV-1 was assessed. Methods: The SARS-CoV-2 S protein sequence was aligned to those of SARS-CoV-1, Middle East respiratory syndrome (MERS) and common-cold coronaviruses. Abilities of mAbs generated against SARS-CoV-1 S protein to bind SARS-CoV-2 or its S protein were tested with SARS-CoV-2 infected cells as well as cells expressing either the full length protein or a fragment of its S2 subunit. Quantitative ELISA was also performed to compare binding of mAbs to recombinant S protein. Results: An immunogenic domain in the S2 subunit of SARS-CoV-1 S protein is highly conserved in SARS-CoV-2 but not in MERS and human common-cold coronaviruses. Four murine mAbs raised against this immunogenic fragment could recognise SARS-CoV-2 S protein expressed in mammalian cell lines. In particular, mAb 1A9 was demonstrated to detect S protein in SARS-CoV-2infected cells and is suitable for use in a sandwich ELISA format. Conclusion: The cross-reactive mAbs may serve as useful tools for SARS-CoV-2 research and for the development of diagnostic assays for COVID-19.

Beyond Shielding: The Roles of Glycans in SARS-CoV-2 Spike Protein

“…74 In this respect, several SARS-CoV-2 antibodies targeting the S protein have been identified (Table S11). 61,62,[64][65][66][67][68][75][76][77][78][79] The majority of these antibodies recognizes epitopes on the RBD, while only a few have been shown to address other antigenic regions within the NTD and CD ( Figure S12). Among the RBD antibodies, B38 interacts with the RBM at the RBD/ACE2 interface, 64 whereas S309 and CR3022 target the side/bottom part of the RBD.…”

“…61,62,65 In addition, 4A8 and 1A9 have been found to engage with the NTD and CD, respectively. 67,68 Analysis of the glycan shield effective on these epitopes is provided in Section 3 of SI. .…”

Laboratory-Based Resources for COVID-19 Diagnostics: Traditional Tools and Novel Technologies. A Perspective of Personalized Medicine

“…The full research cycle takes at least 1.5–2 h and requires special laboratory equipment (automatic ELISA analyzer or (in simplified format) microplate spectrophotometer, thermostatic shaker and tablet washing device) [ 23 , 49 , 50 , 51 , 52 , 53 ].…”

“…However, a potential cross-reactivity cannot be completely ruled out when conducting ELISA tests. False-positive results may occur in the case of infection caused by another type of β-coronavirus, if nucleocapsid N is used as an antigen in test systems [ 46 , 49 , 50 , 51 , 52 ]. According to manufacturers, most of the serological ELISA tests have a specificity of more than 99% and a sensitivity of 96% or more [ 54 , 55 ].…”

Virus isolation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for diagnostic and research purposes

“…24 Numerous SARS-CoV antibodies (including examples against all major structural proteins) have been shown to also bind the corresponding SARS-CoV-2 antigens, including the relatively genetically diverse Spike. 15,[25][26][27] This allows repurposing of these antibodies for several applications including immunofluorescence, Western blot and enzyme-linked immunosorbent assay (ELISA). 25…”