Goats, transgenic, milk from

Due to discrimination from species to species, protein A resins can be used to separate monoclonal antibodies from transgenic milk. Autologous antibodies are not adsorbed if the animal is well chosen. For instance, monoclonal humanized IgG expressed in goat milk can be separated. 

Maga, E.A., Shoemaker, C.F., Rowe, J.D., BonDurant, R.H., Anderson, G.B., and Murray, J.D. (2006). Production and processing of milk from transgenic goats expressing human lysozyme in the mammary gland. ]. Dairy Sci. 89,518-524. 

High expression levels of proteins are potentially attained. In many instances, the level of expression exceeds 1 g protein/litre milk. In one case, initial expression levels of 60 g l-1 were observed, which stabilized at 35 g L1 as lactation continued (the expression of the arantitrypsin gene, under the influence of the ovine P-lactoglobulin promoter, in a transgenic sheep). Even at expression levels of 1 g L1, one transgenic goat would produce a similar quantity of product in 1 day as would be likely recoverable from a 50-1001 bioreactor system. 

Figure 12.10 Outline of the production and purification of antithrombin from the milk of transgenic goats. Purification achieves an overall product yield in excess of 50 per cent, with a purity greater than 99 per cent...

Figure 3.8. The production and purification of tPA from the milk of transgenic goats (WAP = murine whey acid). The downstream processing procedure yielded in excess of an 8000-fold purification factor with an overall product yield of 25%. The product was greater than 98% pure, as judged by SDS-electrophoresis...

Proteinaceous drugs such as insulin for diabetes mellitus, growth hormone for hypopituitary dwarfism, and oxytocin in dysfunctional labor are destroyed in the stomach, and therefore are not given orally. The first drug in milk will be obtained from transgenic goat, owned by GTC Bio-... 

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. 

Brian Turner ( ASF Bioresearch Corporation) presented a case study on the purification and characterization of human anti-TNF from the milk of transgenic goats. -A collaboration with Genzyme Transgenics Corporation... 

With successful advances in research, several other recombinant proteins of pharmaceutical interest have been developed from the milk of transgenic animals. In this context, some human proteins have already been expressed with success. Products such as insulin and growth hormone have also been obtained from the milk of transgenic cows, sheep, or goats (Margawati, 2003). 

Until now, only one product derived from transgenic technology, namely goat milk-derived recombinant human antithrombin III, has been submitted for approval in Europe. 

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