A Stabilized, Monomeric, Receptor Binding Domain Elicits High-Titer Neutralizing Antibodies Against All SARS-CoV-2 Variants of Concern

Ahmed, S and Khan, MS and Gayathri, S and Singh, R and Kumar, S and Patel, UR and Malladi, SK and Rajmani, RS and van Vuren, PJ and Riddell, S and Goldie, S and Girish, N and Reddy, P and Upadhyaya, A and Pandey, S and Siddiqui, S and Tyagi, A and Jha, S and Pandey, R and Khatun, O and Narayan, R and Tripathi, S and McAuley, AJ and Singanallur, NB and Vasan, SS and Ringe, RP and Varadarajan, R (2021) A Stabilized, Monomeric, Receptor Binding Domain Elicits High-Titer Neutralizing Antibodies Against All SARS-CoV-2 Variants of Concern. In: Frontiers in Immunology, 12 .

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Abstract

Saturation suppressor mutagenesis was used to generate thermostable mutants of the SARS-CoV-2 spike receptor-binding domain (RBD). A triple mutant with an increase in thermal melting temperature of ~7°C with respect to the wild-type B.1 RBD and was expressed in high yield in both mammalian cells and the microbial host, Pichia pastoris, was downselected for immunogenicity studies. An additional derivative with three additional mutations from the B.1.351 (beta) isolate was also introduced into this background. Lyophilized proteins were resistant to high-temperature exposure and could be stored for over a month at 37°C. In mice and hamsters, squalene-in-water emulsion (SWE) adjuvanted formulations of the B.1-stabilized RBD were considerably more immunogenic than RBD lacking the stabilizing mutations and elicited antibodies that neutralized all four current variants of concern with similar neutralization titers. However, sera from mice immunized with the stabilized B.1.351 derivative showed significantly decreased neutralization titers exclusively against the B.1.617.2 (delta) VOC. A cocktail comprising stabilized B.1 and B.1.351 RBDs elicited antibodies with qualitatively improved neutralization titers and breadth relative to those immunized solely with either immunogen. Immunized hamsters were protected from high-dose viral challenge. Such vaccine formulations can be rapidly and cheaply produced, lack extraneous tags or additional components, and can be stored at room temperature. They are a useful modality to combat COVID-19, especially in remote and low-resource settings. Copyright © 2021 Ahmed, Khan, Gayathri, Singh, Kumar, Patel, Malladi, Rajmani, van Vuren, Riddell, Goldie, Girish, Reddy, Upadhyaya, Pandey, Siddiqui, Tyagi, Jha, Pandey, Khatun, Narayan, Tripathi, McAuley, Singanallur, Vasan, Ringe and Varadarajan.

Item Type:	Journal Article
Publication:	Frontiers in Immunology
Publisher:	Frontiers Media S.A.
Additional Information:	The copyright for this article belongs to the Author.
Keywords:	addavax; epitope; gamma interferon; immunoglobulin G; immunoglobulin G1; ketamine; monoclonal antibody; neutralizing antibody, antibody titer; Article; bacterium culture; binding assay; cell infiltration; clinical article; dissociation constant; electroporation; enzyme linked immunosorbent assay; expression vector; female; flow cytometry; fluorometry; freeze drying; genetic transfection; heat tolerance; histopathology; human; hybridoma; IC50; immunization; immunogenicity; isothermal titration calorimetry; melting point; melting temperature; mouse; nonhuman; protein structure; receptor binding; Severe acute respiratory syndrome coronavirus 2; surface plasmon resonance; thermostability; variant of concern; virus neutralization; virus replication
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Biological Sciences > Microbiology & Cell Biology Division of Biological Sciences > Centre for Infectious Disease Research Autonomous Societies / Centres > Society for Innovation and Development
Date Deposited:	12 Jan 2022 05:46
Last Modified:	12 Jan 2022 05:46
URI:	http://eprints.iisc.ac.in/id/eprint/70930

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