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Lecture 38 Plantibodies. ANTIBODIES PRODUCED FROM PLANTS. Functional antibodies can be produced from plants Targeted to intercellular space, chloroplast, seeds and tubers Benefit for topical immunotherapy Can be produced from plants in large quantities. Contd.
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ANTIBODIESPRODUCED FROM PLANTS • Functional antibodies can be produced from plants • Targeted to intercellular space, chloroplast, seeds and tubers • Benefit for topical immunotherapy • Can be produced from plants in large quantities Contd...
Plantibodies provides increased stability • e.g: Secretory Ig A • Plants can assemble complex secretory antibodies • e.g: Construction of tobacco plants expressing 4 transgenes • Quadruple transgenics efficiently assembled secretory immunoglobulins • (Smith & Glick, 2000)
Anti-rabies virus mAb • After exposure treated with Ab • Used to be made in horses • First mAb made in transgenic plants • 4 genes – 2 H, 2 L • Transgenic plant for each one and crossing plants • Later used single binary vector with two promoters
Full-size monoclonal antibodies recently produced in transgenic plants
Abs expressed in transgenic plants Constant domains Variable Light chain Variable Heavy chain Recombinant hinge region
Functional Abs • Need to be properly folded and assembled • Need disulfide bond formation and glycosylation • Down stream processing: • Purification of Ab mostly with Protein A or G • Glycosylation is different in plants • β 1,2 Xylose and α 1,3 fucose • Retain in ER, only mannose is attached • Shorter half-life of Ab
Glycosylation of Ab Full-size Ab Large single-chain Ab Camelid heavy-chain Ab Minibodies and Fab fragments don’t get glycosylated
Antibodies: a compelling success story • high specificity: in vitro and in vivo diagnostics • low toxicity: therapeutic applications • high drug approval rates (24 approved mAbs) • major products in biotechnology (~240 in clinical trials) • inherently stable human proteins • injectable, topical and oral applications • applicable for chronic conditions • potential long-lasting benefits
Production Costs for Antibodies Production costs cost in $ / gram hybridomas 1000 transgenic animals 100 transgenic plants 10 Source: Daniell et al. (2001) TIPS 6, 219-226 E. coli & yeast Transgenicplants Tr. animals andanimal cells
Comparison of Mammalian and Plant-produced Antibodies • peptide sequence: identical • correct cleavage of Ig-derived signal peptides • kinetics & affinity: identical • stability in seeds > 30 months • antibody types: plant system more versatile (sIgA) • post-translational processing: different • core glycan identical, terminal sugar different plus xylose & fucose • antigenicity & clearance: apparently identical (shorter half-life)