The Generation of Transgenic Mice Expressing Human Antibody Repertoires

Introduction of exogenous genes into the mouse germline, even followed by tissue specific expression, has been achieved for many transgenes. In addition, gene targeting in embryonic stem cells has silenced undesirable loci. Although several companies offer the production of transgenic mice by DNA microinjection and/or embryonic stem (ES) cell manipulation, only partial information is available regarding preparative methodologies. Here we provide detailed protocols, all routinely used in our laboratories, of DNA purification, ES cell maintenance and the introduction of large gene loci on yeast artificial chromosomes (YACs) into ES cells by protoplast fusion. These methods resulted in transgenic and knock-out animals and several mouse strains with single authentic copies of a human Ig loci integrated randomly in a mouse chromosome; the largest region being over 1000 kb.