This translates into total annual requirements of hundreds of kilograms of any given monoclonal antibody. We have expressed a broad range of monoclonal antibodies in transgenic animals, including mouse antibodies, both partially humanized and fully human antibodies, fusion proteins containing antibody molecules linked to enzymes for in vivo targeting, antibodies comprised of a single light chain, and hybrid molecules containing ligands attached to an immunoglobulin-like scaffold. Genzyme Transgenics has successfully produced over 20 monoclonal antibodies or Ig fusions in the milk of transgenic animals. These are among the most complex recombinant proteins to be expressed transgenically. They require stable integration of two gene constructs, simultaneous synthesis of two proteins in the same cells in roughly equal proportions, and proper assembly into tetrameric protein complexes.
Goats are an ideal dairy species.
They have reasonably short gestation and maturation times, produce large volumes of milk with a high protein content, and are generally accepted as a source of dietary milk. They are relatively easy to breed and maintain. Goat milk has been extensively characterized biochemically, and this makes it more straightforward to develop protein purification procedures. The breeds of goats that we use are prodigious milk producers, yielding an average of 2.5 liters of milk per day. A typical goat can produce 800 or more liters of milk over a 10-month lactation period.