Recent progress on technologies and applications of transgenic poultry

Abstract

Manipulation of the poultry genome has the potential to improve poultry production and offer a powerful bioreactor for the production of pharmaceutical and industrial proteins in eggs. However, before realizing this, the methods for producing transgenic poultry must become routine. The direct modification of an embryo with DNA or viral vectors is possible, but this approach does not have the ability to make locus-specific modifications to the genome. To overcome this problem, several cell-based protocols, which use mainly blastodermal cells (BDCs), embryonic stem cells (ESCs), primordial germ cells (PGCs) and spermatogonial stem cells (SSCs) have been developed to generate transgenic chickens. At present, the complete system for isolating, expanding, transfecting, selecting and re-expanding embryonic stem cell cultures and the subsequent production of high-grade somatic chimeras has been reported, but germline chimeras with transgenic progeny have not yet been achieved. Although the use of viral systems can achieve highly efficient gene transfer, the potential safety issues may limit their practical application. Among the many possible permutations and combinations of target cell and gene transfer methods described in this review, targeting SSCs in vitro using non-viral-based gene transfer and re-injecting them to cock testis is the most efficient and cost-effective strategy to produce transgenic poultry. Key words: Genetic modification, embryo, blastodermal cells, primordial germ cells, stem cells, viral vector.