Antibody and Vaccine production in Plants

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Antibody and Vaccine production in Plants

• Plant biopharming of monoclonal antibodies
• Virus Research 111 (2005) 93100
• Kisung Ko, Hilary Koprowski
• Plant-produced vaccines promise and reality
• Edward P Rybicki

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PLANT-DERIVED BIOMEDICALS FOR TREATMENT OF
INFECTIOUS DISEASES

PLANT-DERIVED BIOMEDICALS FOR TREATMENT OF CANCER
 
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Antibodies

• Magic bullets
• Therapeutic inhibit target involved in disease
  progression
• Diagnostic
• Prevention of disease
• Cause cytotoxic death of target cells
• Act as carriers for radioisotopes, toxins and
  drugs to site of disease

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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

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Full-size monoclonal antibodies recently
produced in transgenic plants
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Abs expressed in transgenic plants
Constant domains
Variable Light chain
Variable Heavy chain
Recombinant hinge region
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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
• ß 1,2 Xylose and a 1,3 fucose
• Retain in ER, only mannose is attached
• Shorter half-life of Ab

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Glycosylation of Ab
Full-size Ab Large single-chain Ab Camelid
heavy-chain Ab
Minibodies and Fab fragments dont get
glycosylated
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Glycosylation in Golgi
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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

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Production Costs for Antibodies
Production costs
cost in /
gram
hybridomas
1000
transgenic animals
100
transgenic plants
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Source Daniell et al. (2001) TIPS 6, 219-226
E. coli yeast
Tr. animals andanimal cells
Transgenicplants
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Comparison of Mammalian and Plant-produced
Antibodies

• peptide sequence identical
• correct cleavage of Ig-derived signal peptides
• kinetics affinity identical
• stability in seeds gt 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)

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Vaccines

• Hepatitis B virus surface antigen HBsAg
• Norwalk virus capsid
• Vibrio cholerae enterotoxin subunit
• Animal vaccines
• Mink enteritis virus - MEV
• Rabbit haemorrhagic disease virus - RHDV
• Foot and mouth disease virus - FMDV

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Oral vaccines

• First thought edible vaccines good idea
• Banana a day
• Oral vaccination
• Might elicit antigenic tolerance
• ProdiGene - Got contamination of maize and
  soybean harvest in 2002 with transmissible
  gastroenteritis virus TGEV

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Past and Future of PMPs
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Plant produced Vaccines

• HPV L1 forms VLPs can protect
• Measles virus haemagglutinin
• HBsAg
• Porcine TGEV
• Tetanus toxin
• Vacinia virus B5
• Allergy vaccines
• HPV
• HIV gp41
• Newcastle disease virus
• Rotavirus VP7

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Cancer Vaccines

• LSBC - Large Scale Biology Crop
• Individually tailored single chain variable
  region Ab fragments from patients with
  Non-Hodgkin lymphomas
• Colorectal cancer antigen
• Cervical Cancer HPV E7

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Vaccines against biothreat agents

• Biodefence
• Anthrax
• Plague
• Ricin
• Haemorrhagic fever

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PMP Development - Highlights

• Series of plant-derived vaccines from Arizona
  State University have completed clinical trials
• Prodigene has trialled two plant-derived vaccines
• LSBC pipeline of cancer vaccines prior to
  insolvency
• Guardian Bioscience coccidiosis vaccine, CFIA
  phase II ongoing
• Fraunhofer CMB, rabies vaccine trialled in humans
• DowAgro Newcastle disease vaccine, approved Feb
  2006
• Heberbiovac (Cuba) approved antibody for HepB
  vaccine purification

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Current Challenges in Molecular Farming

• yield of recombinant proteins
• real quantitative comparison (TSP vs
  pg/cell/24h)
• protein stability (proteases)
• post-translational modification(s)
• backcrossing in elite lines
• extraction and downstream processing
• QA, QC and substantial equivalence
• clinical trials regulatory approval

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Regulatory Challenges for PMP

• loci of transgene insertion
• expression properties and levels, including PTM
• effects of the transgene on the expression of
  flanking endogenous genes
• master line banking to ensure product consistency
• contamination with animal excreta, pesticides,
  organic fertiliser
• procedures for detection and removal of weeds and
  pests
• cultivation variables

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Roadmap Plants for the Future
Plant production platforms

• Vitamines
• Fatty acids
• Enzymes
• Bio-polymers
• Pigments
• Pharmaceutical products
• Fibers

Health food and quality

• Amino acids
• Oil
• Starch

Plant protection
Efficient agriculture
Stress resistance

• Viruses
• Nematodes
• Fungi
• Insects

• Cold
• Drought
• Salinization

• Bt technology
• Herbicide resistance

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