Dr. Baltimore’s team is exploring a new way of stimulating the immune system to fight infectious diseases, focusing on HIV. The premise of this project is that for some infections, including HIV, the immune system’s natural responses are inherently inadequate, and the traditional approach of using vaccines to stimulate and boost these responses is likely to be ineffective. As an alternative, Dr. Baltimore and his colleagues propose to "engineer immunity," that is, use genetic engineering methods to produce immune cells that will make specific antibodies to fight off infection.