Cereal crops as viable production and storage systems for pharmaceutical scFv antibodies

This report describes the stable expression of a medically important antibo dy in the staple cereal crops rice and wheat. We successfully expressed a s ingle-chain Fv antibody (ScFvT84.66) against carcinoembryonic antigen (CEA) , a well characterized tumor-associated marker antigen. scFv constructs wer e engineered for recombinant antibody targeting to the plant cell apoplast and ER. Up to 30 mu g/g of functional recombinant antibody was detected in the leaves and seeds of wheat and rice. We confirmed that transgenic dry se eds could be stored for at least five months at room temperature, without s ignificant loss of the amount or activity of scFvT84.66. Our results repres ent the first transition from model plant expression systems, such as tobac co and Arabidopsis, to widely cultivated cereal crops, such as rice and whe at, for expression of an antibody molecule that has already shown efficacy in clinical applications. Thus, we have established that molecular pharming in cereals can be a viable production system for such high-value pharmaceu tical macromolecules. Our findings provide a strong foundation for exploiti ng alternative uses of cereal crops both in industrialized and developing c ountries.