Engineering the chloroplast genome for hyperexpression of human therapeutic proteins and vaccine antigens.

The chloroplast genome is ideal for engineering because it offers a number of attractive advantages, including high-level gene expression, the feasibility of expressing multiple genes or pathways in a single transformation event, and transgene containment due to lack of pollen transmission. The chloroplast-based expression system is suitable for hyperexpression of foreign proteins, oral delivery of vaccine antigens and therapeutic proteins, via both leaves and fruits. Through the refinement of expression vectors and use of chaperones, chloroplasts produce up to 47% of foreign protein in the total cellular protein in transgenic tissues. This chapter describes various techniques for creating chloroplast transgenic plants and their biochemical and molecular characterization. Suitable examples for application of chloroplast genetic engineering in human medicine are provided.