From recombinant proteins to plant-made-pharmaceuticals
The plant-based production of biopharmaceuticals has attracted interest because plants, compared to traditional platforms for the production of recombinant proteins, are inexpensive, highly scalable and safe. The number of products in development is increasing as tools and strategies have been developed to accumulate recombinant proteins with specific glycan modifications in various plant species and organs. Different platforms have been established including transient expression systems, contained systems based on cultured plant cells, and stable transgenic plants accumulating recombinant proteins in leaves, seeds, fruits or tubers/roots. Plant systems appear particularly suitable for the production of antibodies that are required in large amounts. Antibody 2G12 for example is one of a small number of human IgG monoclonal antibodies exhibiting potent and broad HIV-1-neutralizing activity in vitro, and the ability to prevent HIV-1 infection in animal models. We have expressed this antibody in tobacco and maize, which could facilitate inexpensive, large-scale production. The specific antigen-binding function of the antibody purified from both plant species was verified by surface plasmon resonance analysis, and in vitro cell assays demonstrated that the HIV-neutralizing properties of the plant-produced antibody were equivalent to or better than those of its CHO-derived counterpart. Clinical studies with plant-derived antibody are being initiated.