Transgenic pea seeds as bioreactors for the production of a single-chain Fv fragment (scFV) antibody used in cancer diagnosis and therapy

Field pea (Pisum sativum L.) appears well suited for the production of high -value molecules such as recombinant antibodies, with well-established agri cultural practices world-wide and seeds that are easily stored and distribu ted. In order to evaluate the suitability of this grain legume for the prod uction of biologically active antibodies, we transformed peas with a cDNA e ncoding the single-chain Fv fragment scFvT84.66. This scFv is derived from the monoclonal antibody T84.66, which recognises the well-characterised tum our-associated carcinoembryonic antigen. The antibody is useful for in vitr o immunodiagnosis and in vivo imaging of human cancers. We expressed scFvT8 4.66 cDNA under the control of the seed-specific legumin A promoter. We tar geted the antibody to the endoplasmic reticulum for better stability and hi gh accumulation. Transgenic plants produced up to 9 mu g per gram fresh wei ght of functional scFvT84.66 in their seeds. The transgene was stably inher ited and expressed in the progeny, and the antibody remained active after s torage in dried transgenic seeds for two months at room temperature. Our re sults demonstrate the suitability of grain legume seeds to produce biologic ally active recombinant antibodies, and the utility of field pea seeds as p roduction vehicles for recombinant pharmaceutical macromolecules.