Host Systems

The three host systems.

Soybean

Soybeans (Glycine max) represent our host system for production of seed-based pharmaceuticals. Soybeans contain nearly 40% protein by weight and represent one of the richest natural sources of protein in the world. Seed specific promoters and regulatory elements can be used to target protein accumulation to various stable subcellular locations within the seed. Despite being technically challenging and relatively time consuming, the advantages of using soybeans as a host are well worth the extended times need for transformation and regeneration. Seeds and soy-based intermediates (e.g. soy meal, soy powder, etc.) can be stored for extended periods of time without a requirement for a cold chain, offering a platform technology that is practical and feasible for producing vaccines for Developing countries. We have stored soybeans containing a vaccine antigen for >4 years under ambient laboratory conditions and shown that these stored seeds contained as much vaccine antigen as fresh seeds harvested four years earlier (see Oakes et al link here). Soybeans are also inexpensive to grow, and are well-tolerated for the majority of human and animal populations.

Tobacco

Tobacco is used as a model system to evaluate novel promoters, regulatory elements, and expression construct design. Tobacco transformation is relatively inexpensive compared with soybean transformation, and the generation time is also much quicker than soybean. These factors allow for a cost-effective evaluation of novel elements and gene design before moving into the soybean system.

Arabidopsis

Arabidopsis is also used as a model system to evaluate novel promoters, regulatory elements, and expression cassette design. Transformation of Arabidopsis is perhaps technically the most simple of all higher plants, and the generation time is only 6-8 weeks long. The Arabidopsis system also allows us to evaluate and improve expression cassette design before moving into the soybean system.

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