BCR and hemophilia: Xiaolei Pei and colleagues collected serum and PBMCs from 89 patients with hemophilia and analyzed the antibodies of AAV2 or its derived peptides through neutralizing antibody assay, binding antibody assay, BCR flow cytometry, and B cell ELISpot assay and the inhibitory capacity of peptides against AAV2 transduction both in vitro and in vivo.