B cells produce antibodies (Ab), play an essential role in the immune system and are important therapeutic targets. As hybridomas, B cells are also key for biotechnological production of recombinant monoclonal immunoglobulin (Ig) reagents. The possibility of engineering the B-cell genome for Ig production has potentially far-reaching interests in human health through vaccines, cancer, auto-immunity, infectious or genetic diseases and biomedical diagnosis applications. However, primary B-cells remain difficult to modify genetically. Gene editing technology is not commonly used in B cells to induce the production of a desired Ab instead of the cells’s own Ig. We have recently discovered a new system for efficient gene delivery to human and murine B-cells, which we propose to exploit for CRISPR/cas9 genome editing. Three laboratories will collaborate to develop tools and therapeutically-relevant applications in human and murine models. The efforts will initially be focused on editing the Ig heavy chain gene locus. One goal is to precisely redirect antibody specificity by induced antigenic-specificity replacement (iASR). Well-described Ab will be used to test iASR strategies in vitro and in vivo. Another goal is to modify IgH constant region to force a specific class switch recombination (iCSR). This strategy will be developed to generate IgM Abs for diagnostics and blood cell typing. Overall this project’s ambition is to overcome technological limitations to obtain an efficient platform for B-cell enginering and vectored antibody therapy.