SARS-CoV-2 sculpts the immune system to induce sustained virus-specific naïve-like and memory B cell responses

de Campos-Mata, L.; Tejedor Vaquero, S.; Tacho-Pinot, R.; Pinero, J.; Grasset, E. K.; Arrieta Aldea, I.; Rodrigo Melero, N.; Carolis, C.; Horcajada, J. P.; Cerutti, A.; Villar-Garcia, J.; Magri, G.

SARS-CoV-2 infection induces virus-reactive memory B cells expressing unmutated antibodies, which hints at their emergence from naive B cells. Yet, the dynamics of virus-specific naive B cells and their impact on immunity and immunopathology remain unclear. Here, we longitudinally studied moderate to severe COVID-19 patients to dissect SARS-CoV-2-specific B cell responses overtime. We found a broad virus-specific antibody response during acute infection, which evolved into an IgG1-dominated response during convalescence. Acute infection was associated with increased mature B cell progenitors in the circulation and the unexpected expansion of virus-targeting naive-like B cells that further augmented during convalescence together with virus-specific memory B cells. In addition to a transitory increase in tissue-homing CXCR3+ plasmablasts and extrafollicular memory B cells, most COVID-19 patients showed persistent activation of CD4+ and CD8+ T cells along with transient or long-lasting changes of key innate immune cells. Remarkably, virus-specific antibodies and the frequency of naive B cells were among the major variables defining distinct immune signatures associated with disease severity and inflammation. Aside from providing new insights into the complexity of the immune response to SARS-CoV-2, our findings indicate that the de novo recruitment of mature B cell precursors into the periphery may be central to the induction of antiviral immunity.