Diversification of the VH3‐53 immunoglobulin gene segment by somatic hypermutation results in neutralization of SARS‐CoV‐2 virus variants

• Published in: European journal of immunology Vol. 54; no. 7; pp. e2451056 - n/a
• Main Authors: Bruhn, Matthias, Obara, Maureen, Salam, Abdus, Costa, Bibiana, Ziegler, Annett, Waltl, Inken, Pavlou, Andreas, Hoffmann, Markus, Graalmann, Theresa, Pöhlmann, Stefan, Schambach, Axel, Kalinke, Ulrich
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.07.2024
• Subjects: Affinity maturation; Antibodies, Monoclonal - immunology; Antibodies, Neutralizing - immunology; Antibodies, Viral - immunology; B cells; B-Lymphocytes - immunology; Cell differentiation; Clonotype; Convalescence; COVID-19; COVID-19 - immunology; COVID-19 Vaccines - immunology; CXCR3 protein; Diversification; Humans; Immunoglobulin Variable Region - genetics; Immunoglobulin Variable Region - immunology; Immunoglobulins; Immunologic Memory - immunology; Immunological memory; Lymphocytes B; Memory B Cells - immunology; Memory cells; Monoclonal antibodies; Monoclonal antibody; Neutralization breadth; RNA viruses; SARS-CoV-2 - immunology; Sequence analysis; Severe acute respiratory syndrome coronavirus 2; Somatic hypermutation; Somatic Hypermutation, Immunoglobulin - genetics; Spike Glycoprotein, Coronavirus - genetics; Spike Glycoprotein, Coronavirus - immunology; Transcriptomics; Vaccination; VH3‐53; Virus variants; Virus variants; Clonotype; Somatic hypermutation; Neutralization breadth; Affinity maturation; B cells; Monoclonal antibody; VH3‐53; Diversification
• ISSN: 0014-2980; 1521-4141; 1521-4141
• DOI: 10.1002/eji.202451056

COVID‐19 induces re‐circulating long‐lived memory B cells (MBC) that, upon re‐encounter with the pathogen, are induced to mount immunoglobulin responses. During convalescence, antibodies are subjected to affinity maturation, which enhances the antibody binding strength and generates new specificities that neutralize virus variants. Here, we performed a single‐cell RNA sequencing analysis of spike‐specific B cells from a SARS‐CoV‐2 convalescent subject. After COVID‐19 vaccination, matured infection‐induced MBC underwent recall and differentiated into plasmablasts. Furthermore, the transcriptomic profiles of newly activated B cells transiently shifted toward the ones of atypical and CXCR3+ B cells and several B‐cell clonotypes massively expanded. We expressed monoclonal antibodies (mAbs) from all B‐cell clones from the largest clonotype that used the VH3‐53 gene segment. The in vitro analysis revealed that some somatic hypermutations enhanced the neutralization breadth of mAbs in a putatively stochastic manner. Thus, somatic hypermutation of B‐cell clonotypes generates an anticipatory memory that can neutralize new virus variants. Affinity maturation enhances the potency and neutralization breadth of antibodies. We describe an immunodominant B‐cell clonotype, in which some clones with specific somatic hypermutations gained the ability to neutralize certain SARS‐CoV‐2 variants. Our results support the concept that B cells form an anticipatory memory to counteract viral immune escape.