Development of Plant-produced E2 Protein for Use as a Green Vaccine Against Classical Swine Fever Virus

Abstract

Plants are promising host systems for recombinant protein production. However, progress in the commercialization of plant-made proteins (PMPs) has been slow. Only one PMP drug is commercially available. In this study, we explored the possibility of using plants to produce E2 of classical swine fever virus (CSFV) and the use of this plant-produced E2 as a vaccine. We designed high-level expression vectors for transgenic plants by considering the transcription, translation, and storage of E2 in the cell. We incorporated a cellulosebinding domain sequence into the expression vector as an affinity tag for cost-effective, one-step purification. Using this vector, we generated multiple lines of transgenic Arabidopsis thaliana plants expressing a fusion protein of E2 from CSFV at high levels (0.7% of total soluble proteins). ER-targeted E2 fusion protein was successfully purified via a one-step purification process using amorphous cellulose resin. Arabidopsis-produced E2 was recognized by an antibody that detects CSFV antigen. Finally, antisera from mice immunized with E2 fusion protein reacted strongly to the antigens in a CSFV antibody detection kit. Therefore, we propose that plant-produced E2 fusion proteins could be further developed for use as a green vaccine against CSFV in animals.