Direct and rapid modification of a porcine xenoantigen gene (GGTA1)

The ability to modify animal genomes rapidly at a specific locus would be valuable both for research purposes and in the development of animals suitable for xenotransplantation. In a proof-of-concept study, we used a unique, homology-dependent strand transferase protein called drosophila recombination-associated protein (DRAP) and DNA oligonucleotides to modify the porcine gene encoding alpha 1,3 galactosyl transferase (GGTA1). This gene is responsible for generating xenotransplantation antigens resulting in hyperacute rejection. Pronuclear injection of DRAP and mutant oligonucleotides yielded piglets with heritable, modified alleles of GGTA1 in a direct, rapid and efficient manner. Cells derived from these piglets had markedly reduced alpha 1,3 galactosyl sugar epitopes. The simplicity of this method should permit rapid sequential or simultaneous modification of the various genes encoding or producing antigens that impose limits on xenotransplantation as they are discovered.