Abstract
Here, we describe the isolation of 18 unique anti SARS-CoV-2 human single-chain antibodies from an antibody library derived from healthy donors. The selection used a combination of phage and yeast display technologies and included counter-selection strategies meant to direct the selection of the receptor-binding motif (RBM) of SARS-CoV-2 spike protein’s receptor binding domain (RBD2). Selected antibodies were characterized in various formats including IgG, using flow cytometry, ELISA, high throughput SPR, and fluorescence microscopy. We report antibodies’ RBD2 recognition specificity, binding affinity, and epitope diversity, as well as ability to block RBD2 binding to the human receptor angiotensin-converting enzyme 2 (ACE2) and to neutralize authentic SARS-CoV-2 virus infection in vitro. We present evidence supporting that: 1) most of our antibodies (16 out of 18) selectively recognize RBD2; 2) the best performing 8 antibodies target eight different epitopes of RBD2; 3) one of the pairs tested in sandwich assays detects RBD2 with sub-picomolar sensitivity; and 4) two antibody pairs inhibit SARS-CoV-2 infection at low nanomolar half neutralization titers. Based on these results, we conclude that our antibodies have high potential for therapeutic and diagnostic applications. Importantly, our results indicate that readily available non immune (naïve) antibody libraries obtained from healthy donors can be used to select high-quality monoclonal antibodies, bypassing the need for blood of infected patients, and offering a widely accessible and low-cost alternative to more sophisticated and expensive antibody selection approaches (e.g. single B cell analysis and natural evolution in humanized mice).
Keywords: ACE2 competitor; COVID-19; COVID-19 diagnostics; COVID-19 therapeutics; SARS-CoV-2; antibody; antibody cocktail; detecting antibody; neutralizing antibody.
【저자키워드】 COVID-19, neutralizing antibody, SARS-CoV-2, antibody, COVID-19 therapeutics, antibody cocktail, COVID-19 diagnostics, ACE2 competitor, detecting antibody, 【초록키워드】 neutralizing antibody, Evolution, IgG, ACE2, antibody, SARS-COV-2 infection, Infection, diagnostic, SARS-CoV-2 virus, in vitro, monoclonal antibodies, SPR, angiotensin-converting enzyme 2, COVID-19 therapeutics, flow cytometry, ELISA, immune, binding affinity, Spike protein, Receptor binding domain, specificity, Epitopes, fluorescence microscopy, antibody cocktail, mice, SARS-CoV-2 spike protein, therapeutic, Isolation, receptor, virus infection, epitope, receptor-binding motif, yeast, Blood, neutralization titers, binding, Evidence, Combination, Analysis, angiotensin, best, infected patients, healthy donors, naïve, single-chain antibody, authentic SARS-CoV-2 virus, humanized, approach, neutralize, healthy donor, tested, detect, eight, characterized, can be used, unique, recognize, bypassing, inhibit SARS-CoV-2, RBM, single B cell, 【제목키워드】 Human,