HIGH-LEVEL AND STABLE ACCUMULATION OF SINGLE-CHAIN FV ANTIBODIES IN PLANT-STORAGE ORGANS

In order to explore transgenic plants for large-scale production of ph armaceutical proteins as recombinant antibodies, we tried to optimize the accumulation and stability of functionally active single-chain Fv antibodies in transgenic tobacco plants. Two different single-chain Fv antibodies were used for our studies, which were expressed in differe nt plant organs and plant cell compartments. For ubiquitous expression in tobacco plants transcription of the single-chain Fv genes was cont rolled by the strong CaMV 35S promoter. For storage-organ-specific exp ression we used two seed-specific Vicia faba promoters from the legumi n B4 and the unknown seed protein gene. Summing up our results plant e xpression systems where the recombinant antibody fragments are retaine d in the endoplasmic reticulum provide not only high accumulation leve ls of active antibodies in leaves and seeds but also allow short- and long-term storage of highly active immunoglobulins in harvested plant material at room temperature.