Sheep, transgenic

Female sheep, transgenic for the human factor IX gene, have been cloned. The human gene is coupled to the promoter for the ovine (sheep) milk protein /S-Iactoglobulin thus they secrete large amounts of human factor IX in their milk, which can be purified for human therapy. 

Niemann H, Halter R, Carnwath J, et al. Expression of human blood clotting factor VIII in the mammary gland of transgenic sheep. Transgenic Res., 1999 8(3) 237-347. 

Animal cell culture (particularly CHO and BHK cell lines) Transgenic animals (focus thus far is upon sheep and goats) Plant-based expression systems (various)... 

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. 

Animals like Tracy are known as transgenic animals because they contain genes from two different animals. Tracy was transgenic because she carried human DNA inserted into her own sheep DNA. 

Transgenic animals (focus thus far is upon sheep and goats)... 

Varley, J Birch, J. (1999). Reactor design for large scale suspension animal cell culture. Cytotechnology 29(3), 177-205. Wright, G. et al. (1991). High level expression of active human -antitrypsin in the milk of transgenic sheep. Bwj Technology 9, 830-834. 

Wright, G. et al. (1991). High level expression of active human a-1-antitrypsin in the milk of transgenic sheep. Bioj... 

Transgenic pig. rabbit, and sheep by micro injection of foreign DNA iiitu egg nuclei. 

Transgenic animals Complex posttranslational processing not done by cell culture Sheep, goats, and pigs Development in its infancy Regulation issues Transfer of disease/virus... 

Transgenic animals can also secrete proteins such as blood clotting factors needed by human hemophilia sufferers in their milk (Suraokar and Bradley, 2000). On these lines, Polly, a genetically altered sheep was created at the Roslin Institute in Scotland to produce milk that contained the protein used to treat human hemophilia (Pettus, 2006). 

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). 

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