Milk, transgenic animals

More recently, recombinant antibodies (mostly IgGs) have been produced in the milk of transgenic animals [21,22]. In particular, one study with transgenic mice has shown that it is possible to produce a porcine chimeric IgA that can form dimers in the presence of the J chain [23]. However, the production of fully assembled slgA has yet to be reported. 

Table 5.6 Proteins of actual/potential therapeutic use that have been produced in the milk of transgenic animals...

In addition to milk, a range of recombinant proteins have been expressed in various other targeted tissues/fluids of transgenic animals. Antibodies and other proteins have been produced in the blood of transgenic pigs and rabbits. This mode of production, however, is unlikely to be pursued industrially for a number of reasons ... 

Another possible system for the production of therapeutic proteins consists of transgenic animals. Although there is controversy regarding safety and reproducibility, many reports on this subject have been published and some proteins derived from these systems are currently under clinical trials. Parker et al. (2004) purified and characterized human fetoprotein a secreted in transgenic goat milk. This protein, used in the treatment of autoimmune diseases, proved to be identical to the native form by mass spectrometry, circular dichroism, and pharmacokinetic tests. 

Various procedures are used for obtaining humanized or human antibodies. Some of these using microbial or eukaryotic systems of cell expression will be presented further in this chapter. Other means of synthesis of these molecules, such as expression in plants, or even in the milk of transgenic animals, will not be discussed further. 

Modern in vitro fermentation technologies can compete with in vivo production of antibodies regarding concentration and purity of the produced material. In fact, a number of more sophisticated methods of antibody expression have been developed in the last decade the most important are cell culture in protein-free media and the expression in the milk of transgenic animals, in transgenic plants, and in egg yolk. 

The best-known process that uses transgenic animals to produce antibodies is expression in the milk.9 Production of recombinant antibodies in the milk of transgenic animals often presents the advantage of an overexpression level that reaches values as high as several milligrams per milliliters of milk. This is... 

Bovine colostrum as well as milk whey contain essentially bacteria and pyrogenic substances and may contain viruses. Humanized or specifically reconstructed antibodies from transgenic animals can contain traces of endogenous antibodies from the host animal that are very difficult to separate from the newly expressed molecules. 

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