Tricking bacteria to produce Vaccines.

http://www.sciencedaily.com/releases/2009/02/090223221427.htm

I stumbled upon this article on science daily. Bacteria grows Polysaccharides on their cell surface. Polysaccharides are chains of sugar. These Sugars can be recognized by the body as foreign and then eliminated. The Sugars would be linked with proteins that would be injected into the body.
Scientists have learned they can modify the Sugars on the surface by the specific bateria and then have the bacteria produce that mutant Sugar on its cell surface. What this mean is the scientist could make a large quantity of cheap vaccines this way.

Once the Sugars are extracted from the bacteria they are tied to proteins and administered to the patient. Very good article.