Each dot represents one patient, and bars indicate mean with SEM. Table S4. Abstract Memory space B cells play a fundamental role in sponsor defenses against viruses, but to day, their part has been relatively unsettled in the context of SARS-CoV-2. We statement here a longitudinal single-cell and repertoire profiling of the B cell response up to 6?months in mild and severe COVID-19 individuals. Distinct SARS-CoV-2 spike-specific triggered B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory space B cells, including pre-existing cross-reactive seasonal Betacoronavirus-specific clones, were recruited early in the response, neutralizing SARS-CoV-2 RBD-specific clones accumulated with time and mainly contributed to the late, remarkably stable, memory space B cell pool. Highlighting germinal center maturation, these cells displayed clear build up of somatic mutations in their variable region genes over time. Overall, these findings demonstrate that an antigen-driven activation persisted and matured up to 6?months after SARS-CoV-2 illness and AMG-510 may provide long-term safety. (Number?1D; Numbers S1 A and AMG-510 S1B), confirming the S trimetric glycoprotein like a main target of the protecting immune response in individuals. Open in a separate window Number?1 Longitudinal characterization of the humoral response against SARS-CoV-2 in severe and mild COVID-19 individuals (A and B) Anti-SARS-CoV-2 nucleocapsid (N) (A) and AMG-510 spike (S) (B) serum IgG levels were measured by ELISA in 21 severe COVID-19 (S-CoV) and 18 mild COVID-19 (M-CoV) individuals at M0 (white), M3 (light orange), and M6 (dark orange). The dashed collection shows the positivity threshold provided by the manufacturer. (C) Development of anti-SARS-CoV-2?S serum IgG levels over time post sign onset in S-CoV (black dots, dark blue collection) and Rabbit Polyclonal to WEE2 M-CoV (white colored dots, light blue collection) individuals. Continuous lines show linear regression, and coloured area AMG-510 between dashed lines shows error bands (R2?= 0.049 for S-CoV, ns and 0.0061 for M-CoV, ns, Pearson correlation). (D) Correlation between anti-SARS-CoV-2?S serum IgG levels and neutralization potential (% neutralization achieved at a 1/90 dilution) at M6 (n?= 10 S-CoV and 11 M-CoV individuals). The collection represents a simple linear regression (R2 and p value with Pearson correlation are demonstrated) (E) Representative FACS storyline of His-tagged SARS-CoV-2?S staining in gated live CD19+CD38int/?CD27+IgD? B cells at M0 in two representative S-CoV (top storyline) and M-CoV individuals (lower storyline). (F) Overall study design. ANOVA and two-tailed Mann-Whitney checks (A and B). Linear regression with Pearson correlation analysis (D). ???p? 0.001, ??p? 0.01. See also Figure? S1 and Table S1. Open in a separate window Number?S1 Quantification and functional assessment of the anti-SARS-CoV-2 humoral immune response in COVID-19 convalescent individuals, Related to Number?1 (A) Percentage of neutralization shown by individual sera from S-CoV (n?= 10) and M-CoV (n?= 12) individuals at M6 at increasing dilutions. (B) Representative wells for the neutralization assay. Blue places represent SARS-CoV-2 positive cells. (C) Representative results of an anti-SARS-CoV-2?S IgG ELISA on supernatants from sorted SARS-CoV-2 S-specific MBCs (dark dots) and non spike-specific MBCs (white colored dots), as validation of FACS SARS-CoV-2 S-staining. Lines show median value. Dashed line shows the positivity threshold (3 x blank). (DCH) Circulation cytometric gating strategies for the analysis and sorting of major B cell populations from PBMCs of convalescent COVID-19 individuals. (D) Gating strategy to analyze SARS-CoV-2 S-specific B cell human population. Lymphocytes were 1st gated based on morphology, before exclusion of doublets, deceased cells and CD3/CD14 cells. CD19+ cells were next gated before exclusion of CD38hi plasma cells. CD38int/- cells were then divided in four quadrants using CD27 and IgD. Upper remaining quadrant defines memory space B cells (MBCs), lower remaining quadrant double-negative (DN), top right quadrant CD27+IgD+ cells (MZB) and lower right quadrant naive B cells (excluding CD38hi transitional). SARS-CoV-2 S-specific B cells were then analyzed within the B cell human population of interest using a double-staining strategy with anti-His antibodies of a His-tagged SARS-CoV-2?S protein. (E) Gating strategy to independent activated and classical switched B cells using CD71, within the IgD-CD27+ gate (F) Gating strategy to analyze.