Vaccination of SARS-CoV-2-infected individuals expands a broad range of clonally diverse affinity-matured B cell lineages

Vaccination of SARS-CoV-2 convalescent individuals generates broad and potent antibody responses. Here, we isolate 459 spike-specific monoclonal antibodies (mAbs) from two individuals who were infected with the index variant of SARS-CoV-2 and later boosted with mRNA-1273. We characterize mAb genetic features by sequence assignments to the donors' personal immunoglobulin genotypes and assess antibody neutralizing activities against index SARS-CoV-2, Beta, Delta, and Omicron variants. The mAbs used a broad range of immunoglobulin heavy chain (IGH) V genes in the response to all subdomains of the spike examined, with similar characteristics observed in both donors. IGH repertoire sequencing and B cell lineage tracing at long-term time points reveals extensive evolution of SARS-CoV-2 spike-binding antibodies from acute infection until vaccination five months later. These results demonstrate that highly polyclonal repertoires of affinity-matured memory B cells are efficiently recalled by vaccination, providing a basis for potent antibody responses observed in convalescent persons following vaccination.

Mark Chernychev, Mrunal Sakharkar, Ruth I. Connor, Haley L. Dugan, Daniel J. Sheward, C. G. Rappazzo, Aron Ståhlmarck, Mattias N. E. Forsell, Peter F. Wright, Martin Corcoran, Ben Murrell, Laura M. Walker, Gunilla B. Karlsson Hedestam