Citation
- Authors: Sokal A. et al.
- Year: 2021
- Journal: Cell 184 1201-1213
- Applications: in vitro / DNA / FectoPRO
- Cell type: Expi293F
Description: Human embryonic kidney Fibroblast
Known as: Expi 293-F, Expi, HEK-293 Expi
Method
The plasmids coding for the recombinant proteins were transiently transfected in Expi293F™ cells (Thermo Fischer) using FectoPRO® DNA transfection reagent (Polyplus), according to the manufacturer’s instructions. The cells were incubated at 37°C for 5 days and then the culture was centrifuged and the supernatant was concentrated. The proteins were purified from the supernatant by affinity and size-exclusion chromatography (SEC). The first purification step was performed using StrepTactin columns (IBA) (SARS-CoV-2 S, OC43 S) or His-Trap™ Excel columns (GE Healthcare) (HKU1 S, SARS-CoV-2 RBD). The different S ectodomains were further purified using a Superose6 10/300 colum (GE Healthcare) equilibrated in PBS, while a Superdex200 10/300 column was used for SARS-CoV-2 RBD.
Abstract
Memory B cells play a fundamental role in host defenses against viruses, but to date, their role has been relatively unsettled in the context of SARS-CoV-2. We report here a longitudinal single-cell and repertoire profiling of the B cell response up to 6 months in mild and severe COVID-19 patients. Distinct SARS-CoV-2 spike-specific activated B cell clones fueled an early antibody-secreting cell burst as well as a durable synchronous germinal center response. While highly mutated memory 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 largely contributed to the late, remarkably stable, memory B cell pool. Highlighting germinal center maturation, these cells displayed clear accumulation 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 infection and may provide long-term protection.