Because of the inconsistent efficacy of the current TB vaccine (BCG), the development of improved TB vaccines and TB immunization strategies is an international research priority. Oral vaccines should permit the design of more convenient immunization strategies and allow the implementation of universal vaccination programs throughout the world. Recent advances in plant molecular biology has strongly suggested that oral vaccines, including an oral tuberculosis preparation, can be produced in edible plants. To develop anti-tuberculosis edible vaccines, we have modified two plant expression vectors. Two immunogenic mycobacterial genes - MPT64 and Esat-6 - have been cloned into these vectors and the recombinants have been transformed into the plant pathogen Agrobacterium tumefaciens. In collaboration with scientists at the University of Maryland, the USDAand NIH, we plan to transform Arabidopsis (a model plant system) and tomato plants with the Agrobacterium transformants. Expression of mycobacterial genes in the transformed plants will then be evaluated. If mycobacterial proteins are detected, the transformed plants will be fed to mice and immune responses to the plant-derived mycobacterial antigens will be assessed.
