Researchers from the National Institute for Medical Research in London report a new vaccine for tuberculosis based on DNA taken from the organism that causes the disease. Between one-third and a half of the world's population carry Mycobacterium tuberculosis, the bacteria which causes the disease. Existing vaccines haven't stopped TB, and resistant strains are emerging. The researchers used DNA and produced a vaccine that boosted the immune response in test mice, helping to clear the bacterium, the scientists write in Nature .