TARGETED INACTIVATION OF MURINE IMMUNOGLOBULIN LOCI

IMMUNO-DEFICIENT MOUSE STRAINS HAVE PLAYED AN IMPORTANT ROLE IN THE ANALYSIS OF THE IMMUNE SYSTEM AND ARE POTENTIALLY VALUABLE IN THE DEVELOPMENT OF ANIMAL MODELS FOR HUMAN DISEASE. A BROAD SPECTRUM OF NATURALLY OCCURING MURINE IMMUNODEFICIENCIES HAVE BEEN DISCOVERED. HOWEVER, NO DEFECTS WHICH FULLY AND SELECTIVELY LIMIT THE SYNTHESIS OF IMMUNOGLOBULINS HAVE BEEN IDENTIFIED. THE GOAL OF PHASE I IS TO GENERATE SUCH AN IMMUNE DEFICIENCY BY MEANS OF TARGETED INACTIVATION OF MURINE IMMUNOGLOBULIN HEAVY AND KAPPA LIGHT CHAIN GENES IN EMBRYONIC STEM (ES) CELLS, FOLLOWED BY DERIVATION OF MICE CARRYING THE INACTIVATED LOCI. THE UTILITY OF THE RESULTING MUTATIONS RESIDES IN PART IN THEIR USE AS A NULL BACKGROUND FOR THE EXPRESSION OF IMMUNOGLOBULIN TRANSGENES, AND IN THEIR POTENTIAL FOR COMBINATION WITH OTHER IMMUNO- DEFICIENCIES TO GENERATE SUPERIOR IMMUNO-DEFICIENT MICE. SPECIFICALLY, IN PHASE II, THE INACTIVATED IMMUNOGLOBULIN LOCI WILL BE BRED INTO MICE EXPRESSING HUMAN IMMUNOGLOBULIN TRANSGENES, UNDER DEVELOPMENT AT GENPHARM, TO GENERATE A MOUSE FROM WHICH HUMAN MABS CAN READILY BE ISOLATED. IN ADDITION, THE HEAVY CHAIN MUTATION WILL ALSO BE INTRODUCED INTO TRANSGENIC IMMUNO-DEFICIENT MICE UNDER DEVELOPMENT, TO ELIMINATE RESIDUAL ANTIBODY SYNTHESIS AND TO PROVIDE A MORE EFFICIENT HOST FOR ENGRAFTMENT OF HUMAN TISSUES.