Minimization of viral contamination in human pharmaceuticals produced in the milk of transgenic goats.

The minimization of viral contamination in therapeutic proteins produced in transgenic goats' milk can be achieved by a combinatorial approach. It begins with reduction in the risk in the starting material followed by appropriate clearance/inactivation steps in the purification process. To minimize risk in the starting material, Genzyme Transgenics Corporation (GTC)'s closed goat herds are subjected to routine serological surveillance for known viral diseases, especially those transmitted through milk. Although scrapie is defined as a slow-acting virus of sheep and goats, its incidence in goats in the US is rare (only four cases) and all four were in goats co-mingled with scrapie-infected sheep. All GTC's domestic goats were selected for previous non-exposure to sheep, cows or scrapie. In addition, milk, which is the starting material for transgenic protein production, is categorized as non-infectious for prions. Standard operating procedures are in place at GTC Farm sites to minimize human, animal or vehicular vectoring of viral diseases and the transgenic production animals are milked according to high standard Good Agricultural Practices (GAP). The transgenic protein (ATIII) purification process contains steps that should provide a high level of viral reduction. Validation of viral and prion removal will also be undertaken.