SBIR-STTR Award

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 occurring 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 GenPhann, to generate a mouse from which human MAbs can readily be isolated. In addition, the heavy chain mutation will also be introduced into transgenic immunodeficient mice under development, to eliminate residual antibody synthesis and to provide a more efficient host for engraftment of human tissues.Awardee's statement of the potential commercial applications of the research:Transgenic mice incapable of expressing endogenous immunoglobulins will enable the generation of therapeutic human monoclonal antibodies from human immunoglobulin transgenes, by eliminating competition from murine antibodies. The inactivated immunoglobulin loci will also be bred with transgenic immuno-deficient mutants to improve their usefulness as hosts for xenografts.National Institute of Allergy and Infectious Diseases (NIAID)

Monoclonal antibodies have been shown to represent an important class of therapeutic proteins with applications in various disease states. We will inactivate the endogenous mouse immunoglobulin (Ig) repertoire to ensure the generation of purely human antibodies from human Ig transgenics, enabling the production of therapeutic human monoclonal antibodies from mice. Human antibodies will provide a safer and more effective alternative to the rodent antibodies now being developed and used as therapeutic agents. Inactivation of the Ig heavy chain and one of the light chain loci (kappa) has been carried out in Phase I. The goal of Phase II is to provide a completely null Ig background in the form of mice and ES cells homozygous for inactivation of all three Ig loci (heavy chain, kappa and lambda light chain), into which will be introduced, respectively, the human Ig minilocus and yeast artificial chromosome (YAC) transgenes under development at GenPharm. The generation of a fully null Ig genotype will enable the synthesis of human antibodies in the absence of competition from mouse Igs. The null Ig genotype will also eliminate the extremely time-consuming breeding programs currently required for introducing transgenes into the Ig deficient backgrounds, considerably accelerating the rate at which transgene function can be assessed. In addition, the Ig-deficient mice also provide a potentially valuable model system for the in vivo analysis of B cell development and function.Awardee's statement of the potential commercial applications of the research: Transgenic mice and ES cell lines will be developed which are incapable of expressing endogenous immunoglobulins. They will enable the generation of therapeutic human monoclonal antibodies from mice bearing human immunoglobulin minilocus or YAC transgenes by eliminating competition from murine antibodies. Human monoclonal antibodies may be particularly important for therapeutic applications such as treating cancers, cardiovascular diseases, septic shock and immunosuppressive diseases.National Institute of Allergy and Infectious Diseases (NIAID)