14 – EXPRESSION OF RECOMBINANT PROTEINS IN THE MILK OF TRANSGENIC ANIMALS

Over 50 proteins have been expressed in the milk of transgenic animals. This chapter focuses on the status of expression of recombinant proteins in such milk. The chapter discusses the expression of therapeutically useful proteins in mammalian milk, the emphasis being on dairy animals as the production systems of choice. The chapter presents an overview of the expression constructs, milk-specific transgenes, transgene insertion, transgenic animal production, milk, and protein purification. The quality regulatory issues related to this are also discussed. The chapter also states that the mammary bioreactor is capable of most posttranslational modifications and protein folding, and can be used to produce complex proteins. The chapter presents the current status where transgenic dairy animals are providing a bulk protein production system. This system is capable of making proteins available that are either not available today or are only recoverable from other sources. Transgenic production may thus enable a move from “on-demand” patient treatment to prophylaxis and far wider indications and use of many proteins. In addition, the production of proteins in the milk of transgenic dairy animals is highly cost-effective, opening up real possibilities for nutraceutical product development.