ABSTRACT
Gene(s) of interest can be modified and reintroduced into animals to create new breeds with desired traits by the technique of transgenesis. The major strategies to generate transgenic animals have gone from pronuclear injection, embryonic stem cells, and nuclear transfer to the latest lentiviral delivery.[13,14] Somatic cell nuclear transfer, a cloning technology introduced in 1996 that involves the injection of nuclei of genetically modified somatic cells into the enucleated oocytes, allows precise targeting of genomes in virtually any animal species. Transgenic animals from all major livestock species have been generated by somatic cell nuclear transfer, but this technique suffers from low efficiency and high technical demands.[13] The lentiviral delivery of transgenes is highly efficient in introducing foreign gene(s) into the germline by taking advantage of the ability of lentivirus to integrate into both dividing and nondividing cells.[13,14] Therefore, it will be economically possible for genetic manipulation of livestock in the future.
