This is a Shannon Award providing partial support for the research projects that fall short of the assigned institute's funding range but are in the margin of excellence. The Shannon Award is intended to provide support to test the feasibility of the approach; develop further tests and refine research techniques; perform secondary analysis of available data sets; or conduct discrete projects that can demonstrate the PI's research capabilities or lend additional weight to an already meritorious application. The abstract below is taken from the original document submitted by the principal investigator. The domestic chicken is a small animal which can be used to produce recombinant pharmaceutical proteins in the egg and other tissues. However, the chicken poses some unique anatomical challenges which make genetic manipulation by microinjection less feasible, and tend to favor retroviral approaches. Chickens produced significant amounts of exogenous protein in vivo when replication-competent avian retroviral vectors were used, but the replication-competent viruses quickly rearranged, deleting the transgenes, and causing fatal tumors which killed most animals. On the other hand, murine retroviral vector systems have not proven very effective for obtaining sustained expression in animals, due to methylation-inactivation during development. Therefore, an alternative retrotransposon vector system (VL30) was developed and used to successfully transfer and express genes in many cell types, including chicken embryos. We will now investigate and optimize methods of gene transfer aimed at obtaining efficient production of pharmaceutical proteins in the avian egg, including: 1) direct gene transfer in embryo, and 2) transduction into embryonic cells ex vivo, together with cell transplantation in embryo. In addition to providing a new method for pharmaceutical protein production, the transgenic technology is also expected to be useful for enhancing the nutritional characteristics of the animal and egg, as well as to provide a new animal model system for investigating genetic disorders and gene therapy. Finally, the results will provide an extra benefit in the form of information about spatial and temporal patterns of expression of VL30 vectors in vivo, relevant to their use for gene therapy in human somatic tissues.