Potent human antibodies against SpA5 identified by high-throughput single-cell sequencing of phase I clinical volunteers’ B cells

The drug resistance problem of <i>Staphylococcus aureus</i> needs to be solved urgently. Here, we report the rapid identification of <i>S. aureus</i> human antibodies by high-throughput single-cell RNA and VDJ sequencing of memory B cells derived from 64 volunteers immunized with recombinant five-component <i>S. aureus</i> vaccine (clinical phase I). From 676 antigen-binding IgG1⁺ clonotypes, TOP10 sequences were selected for expression and characterization, with the most potent one, Abs-9, having nanomolar affinity for the pentameric form of the specific antigen <i>S. aureus</i> protein A. Abs-9 also demonstrated strong prophylactic efficacy in mice injected with lethal doses of a wide range of drug-resistant <i>S. aureus</i> strains. Additionally, the potential epitopes were predicted and validated based on Alphafold2 and molecular docking methods. In all, this study screened for a potent strain of antibody that prevents infection with antibiotic-resistant <i>S. aureus</i>, providing important data to guide the design of vaccines based on antibody architecture.