The hen has long held promise as a low-cost, high-yield bioreactor for the production of human biopharmaceuticals in egg whites using genetic engineering. Recently finding appeared indicating the production of substantial levels of human monoclonal and single chain antibodies (O 3mg and O 150 mg, respectively) in eggs of transgenic hens. These promising findings indicate that the hen is close to becoming a competitive manufacturing platform for the production of human biopharmaceuticals. The most successful method of gene transfer in birds is to use PGC and retroviral vectors injected into the embryos following oviposition. The germline transmission rate of the founder birds is very low. Nevertheless, the transgenic lines demonstrate the stable integration and inheritance of the transgene to subsequent generations. In this review, general avian reproduction and establishment of germ cells will be described for possible routes to gene transfer. Later, the current gene transfer methodologies will be summarized with a focus on PGC gene transfer. Finally, the application of transgenics to poultry will be discussed.
