LECTURE: Using Crop Biotechnology to Reduce the Impact of Infectious Diseases in the Developing World

Oral vaccines are a convenient and potentially safer means of implementing universal vaccination programs in the developing world (as well as in economically advanced countries). Vaccines which would not require refrigeration would greatly reduce the cost of such programs. To meet the needs for temperature stable, oral products, we have genetically engineered crops using genes from human pathogens. We have asked the question if these "pharmacrops" would produce subunits of the pathogens that would induce protective oral immune responses. Three human clinical trials have validated the concept of oral immunization when the plant samples are simply eaten as food. I will discuss our current production system that uses genetic containment greenhouses to grow tomatoes, and food process technology to obtain freeze-dried, tomato fruit-derived, temperature-stabile vaccine doses for clinical trials. The importance of working within a strong regulatory framework to ensure that the GM plants are strictly segregated from crops grown for food consumption will be emphasized. Plant-based vaccines build upon a technology base derived from agriculture and food processing. Because it does not require capital intensive pharmaceutical manufacturing facilities, it could be directly transferred to developing countries to establish a sustainable, in-country capacity for vaccine manufacture. One major outcome of this technology transfer would be for self-sufficiency in public health care needs of poor populations, thereby expanding the global capacity for health promotion