Texas researchers have developed a vaccine in mice against the deadly toxin Ricin, which has been used in the past as a biological weapon. Ricin is a protein produced by castor beans, making it one of the simplest and cheapest bioweapons to produce. Ricin can be administered in foods, water and through the air, and a single Ricin molecule inside a cell is enough to shut down protein synthesis and kill it. But researchers at the University of Texas Southwestern Medical Center at Dallas say that by removing snippets of the Ricin DNA, they were able to develop two strains of mutated Ricin that stimulate an immune response in mice, but cause no harm. The researchers say they believe one or both of the strains would be safe for use in humans. According to the UT team, Iraq is known to have stockpiles of Ricin as part of its bioweapons program, while at least one group associated with Al Qaeda is thought to have experimented with the toxin.