AAB-seq: An antigen-specific and affinity-readable high-throughput BCR sequencing method

B-cell receptor (BCR) sequencing is a powerful antibody discovery tool but current methodology is often inefficient, and lead generation often requires the production and testing of numerous antibody candidates, and it is difficult to provide affinity information for their antibodies at the same time. Here, we introduce AAB-seq (antigen affinity-readable High-throughput BCR sequencing), an efficient antibody screening tool to identify antigen binding affinity of thousands of paired BCRs. It employs fluorophore and DNA barcode-labeled antigen and secondary antibody targeting Ig light chain to label B cells and uses high throughput single cell BCR sequencing and surface protein profiling to obtain the ratio of surface bound antigen to surface BCR in thousands of B-cells. Using AAB-seq, we accurately identified valuable candidate antibodies 1743-3 and 1743-13 from SARS-CoV-2 RBD immunized mouse, providing a basis for further development of SARS-CoV-2 antibody drugs. Thus, AAB-seq allows high throughput identification of antibody sequences paired with antigen affinity, which improves the screening efficiency of functional antibodies and provides an effective solution for the rapid discovery and development of new therapeutic monoclonal antibodies. ### Competing Interest Statement The authors declare the following competing interests: Weiyang Shi has filed apatent (PCTxxx) based on the echnique described in this paper. All other authors declare no competing interests.