New roles for an old-trouper vaccine?

New roles for an old-trouper vaccine?

Using a venerable bacterium that is the basis of the widelyused tuberculosis vaccine, scientists at the Albert Einstein College of Medicine in New York City are hoping to develop a multipurpose vaccine effective against several major health problems, such as leprosy, malaria and parasitic diseases. Barry Bloom, William R. Jacobs and Margareta Tuckman report in the June 11 NATURE that they have designed a genetic-material-carrying "vehicle' called a shuttle phasmid that can enter bacillus Calmette-Guerin (BCG) mycobacteria. Tuberculosis vaccines made from the BCG bacteria, which are harmless relatives of those causing leprosy and tuberculosis, have been injected in an estimated 2.5 billion people.

Created with DNA from a bacteriophage (a virus that infectsbacteria) combined with genetic material called a cosmid from the common bacterium Escherichia coli, the shuttle phasmid can infect mycobacteria and grow in E. coli cultures. According to the authors, the phasmic might be used to transfer genes of disease-causing microorganisms into BCG, making a single vaccine that prevents other diseases in addition to tuberculosis. Much of the current vaccine research is concentrating on the vaccinia virus as a carrier of foreign DNA, but the BCG model may avoid rare vaccinia-associated side effects. However, the New York group has yet to show that the inserted genes remain active inside the mycobacteria.