Elucidating the Humoral Immune Response to SARS-CoV-2: Isolation and Characterization of Monoclonal Antibodies from Convalescent COVID-19 Patients

The COVID-19 pandemic has underscored the importance of understanding the intricate mechanisms of the humoral immune response to SARS-CoV-2. This study aimed to elucidate the diversity and specificity of antibodies generated from convalescent COVID-19 patients by isolating and characterizing monoclonal antibodies (mAbs) targeting the SARS-CoV-2 spike protein. Employing cutting-edge technologies, including single-cell analysis and fluorescence-activated cell sorting, we successfully isolated live memory B cells secreting IgG antibodies from the peripheral blood of convalescent patients. A total of 17 mAbs were generated, encompassing various heavy and light variable genes, with only a few common between patients. In vitro assays demonstrated varying degrees of inhibition against wild-type and Omicron strains, highlighting discrepancies between ACE2 competition and actual neutralization capacity. Bio-layer interferometry and in silico docking analyses revealed unique binding motifs and mechanisms of action, with notable differences in neutralization abilities based on epitope specificity. Furthermore, animal experiments using K18-hACE2 transgenic mice demonstrated the therapeutic potential of these mAbs in preventing SARS-CoV-2 infection. This study provides novel insights into the humoral immune response to SARS-CoV-2 and highlights the importance of patient-derived mAbs as therapeutic agents for COVID-19 treatment and prevention.