The production of pharmaceutical proteins from the milk of transgenic animals.

The preparation of recombinant proteins of pharmaceutical interest from the milk of transgenic animals is becoming a reality. No protein has reached the market yet but several have been prepared in large quantities not only from laboratory animals but also from ruminants (goat and sheep) and pigs. Rabbit appears more and more to be an intermediate animal well adapted for the preparation of limited amounts of proteins. Several problems remain to be solved to optimize the method. The expression level of genes of interest associated with milk protein gene control regions is usually unpredictable. The recombinant proteins secreted in milk are not always in a satisfactory biochemical form. Cleavage and glycosylation are not always carried out correctly. The problem of the possible presence of agents pathogenic for humans in proteins extracted from milk is not completely solved. Prions have not been found in mammary glands and other milk pathogens may be controlled using good practice in breeding.