Deletion of the alpha(1,3)galactosyl transferase (GGTA1) gene and the prion protein (PrP) gene in sheep

Nuclear transfer offers a cell-based route for producing precise genetic mo difications in a range of animal species. Using sheep, we report reproducib le targeted gene deletion at two independent loci in fetal fibroblasts. Vit al regions were deleted from the alpha (1,3)galactosyl transferase (GGTA1)g ene, which may account for the hyperacute rejection of xenografted organs, and from the prion protein (PrP) gene, which is directly associated with sp ongiform encephalopathies in humans and animals. Reconstructed embryos were prepared using cultures of targeted or nontargeted donor cells. Eight preg nancies were maintained to term and four PrP-/+ lambs were born. Although t hree of these perished soon after birth, one survived for 12 days. These da ta show that lambs carrying targeted gene deletions can be generated by nuc lear transfer.