Genetic engineering of B cell receptors and uses thereof in antigen-induced antibody secretion

A method of genetically engineering a primary mammalian cell of the B lineage for expression of an engineered B cell receptor (BCR) and for antigen-induced secretion of an antibody of interest or antigen binding fragment thereof or chimera thereof from said cell and or progeny cell thereof, said method comprising a step of contacting a primary mammalian cell of the B lineage with at least one nucleic acid cassette comprising at least one nucleic acid sequence of interest, or with any vector or vehicle comprising said cassette, wherein said nucleic acid sequence of interest comprises at least one nucleic acid sequence coding 5′ to 3′ for (i) at least one variable domain of an immunoglobulin heavy chain or any binding fragment or chimera thereof, and (ii) at least one variable domain of an immunoglobulin light chain or any binding fragment or chimera thereof, and at least one splice donor site (SD), wherein said cassette is flanked on the 5′ and 3′ ends thereof by universal homology arms for integrating by homologous recombination, wherein said universal homology arms target the insertion of said nucleic acid cassette comprising said nucleic acid sequence of interest into a target genomic sequence within the immunoglobulin heavy chain (IgH) locus, downstream to the last segment of the J region of said IgH locus and upstream of an enhancer region of said IgH locus of said heavy chain of said BCR, and wherein said method genetically engineers the primary cell of the B cell lineage to express an engineered BCR and to secrete the antibody of interest or antigen-binding fragment thereof or chimera thereof by antigen-induced activation from said cell and or progeny thereof.