B cell responses to SARS-CoV-2.

This chapter provides an overview of B cell responses in COVID-19, highlighting the structure of SARS-CoV-2 and its impact on B cell immunity. It explores the production and maturation of SARS-CoV-2-specific B cells, with a focus on the two distinct phases of the humoral immune response: the extrafollicular (EF) phase and the germinal center (GC) phase. Furthermore, the interplay between B cells, follicular T helper cells, CD4+ T cells, and plasma cells is discussed, emphasizing their collaborative role in mounting an effective humoral immune response against SARS-CoV-2. The concept of immunological memory is explored, highlighting the roles of plasma cells and B memory cells in providing long-term protection. The chapter delves into the antibody response during SARS-CoV-2 infection, categorizing the types of antibodies generated. This includes a detailed analysis of neutralizing antibodies, such as those directed against the receptor-binding domain (RBD) and the N-terminal domain (NTD), as well as non-neutralizing antibodies. The role of mucosal antibodies, cross-reactive antibodies, and auto-reactive antibodies is also discussed. Factors influencing the dynamics of anti-SARS-CoV-2 antibodies are examined, including the duration and strength of the humoral response. Additionally, the chapter highlights the impact of the Omicron variant on humoral immune responses and its implications for vaccine efficacy and antibody-mediated protection.