I haven't really studied up on this in years, so I'll tell you what I understand. Hopefully Steve Push will correct me where I'm wrong or out of date.
It is a way of making complex biologics such as glyco-proteins in a cheap manner. This is for high value drugs, not for food. If you want cheap protein, eat tofu or meat. Bacteria can make simple proteins by fermentation fairly readily and cheaply. However, they don't do well making more complex proteins that have side chains on them, such as sugar chains (glyco). Glycoproteins are very common in higher organisms, and many of the biological compounds of interest are glycoproteins. These are currently made by using tissue culture, which is basically done by growing human (or other higher organism) cell lines with the gene inserted for the protein of interest. These higher cells have the processing capability to make more complicated molecules such as glyco-proteins. However, fermentation by tissue culture is fairly expensive, tends to make very small yields, is very susceptible to contamination and tends to be a very tempermental process. However, they have the technology now to put the gene into the mammary glands of mammals, making a transgenic animal who can produce the desired complex protein in their milk. What is interesting about this is that mammary glands are designed to make a very rich exudate loaded with protein. Most other cell lines used in tissue culture can only make very small quantities of protein relative to these mammary glands. Thus transgenic animals can produce very large yields. Plus, they are cheap and easy to maintain relative to a mammalian tissue culture fermentation facility staffed by lots of highly paid humans, using lots of power, reagents, and tending to get contamination ruining the batches of product. Cows, sheep, and goats work cheap, eat cheap and don't tend to have their production effected by contamination (ie. infection in their case). Basically, it is the mammalian equivalent of using a bacteria to produce a drug. While fermentation tends towards micro or milligram per liter yields, transgenic milk production can get into the grams per liter yield ranges. And, the technology keeps getting better. Plus, the recent cloning demonstration will simplify producing herds of high yielding animals, as this was one of the difficult parts of the process, as each producer had to be made individually, and some would yield high levels, and others low levels, now they can make lots of the high yielding animals consistently.
Rman |
