HUMAN FACTOR-IX TRANSGENIC SHEEP PRODUCED BY TRANSFER OF NUCLEI FROM TRANSFECTED FETAL FIBROBLASTS

Ovine primary fetal fibroblasts were cotransfected with a neomycin res istance marker gene (neo) and a human coagulation factor IX genomic co nstruct designed for expression of the encoded protein in sheep milk. Two cloned transfectants and a population ol neomycin (G418)-resistant cells were used as donors for nuclear transfer to enucleated oocytes. Six transgenic lambs were liveborn: Three produced from cloned cells contained factor IX and neo transgenes, whereas three produced from th e uncloned population contained the marker gene only. Somatic cells ca n therefore be subjected to genetic manipulation in vitro and produce viable animals by nuclear transfer. Production of transgenic sheep by nuclear transfer requires fewer than half the animals needed for pronu clear microinjection.