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Future directions for agricultural biotechnology: 

Future directions for agricultural biotechnology Dr. Kirstin Carroll Outreach in Resource Biotechnology Program Oregon State University

Slide2: 

Lecture Outline What is molecular farming in plants? Why use plants? What are the risks and concerns? Current and evolving regulation

Slide3: 

The use of agricultural plants for the production of useful molecules for non food, feed or fiber applications. Plants are already grown to produce valuable molecules, including many drugs. Molecular farming is different because the plants are genetically engineered (GE) to produce the molecules we want them to. What is 'molecular farming in plants'?

Slide4: 

What is GE? Create recombinant DNA with gene from same or different organism Transfer DNA to plant cell (use either Agrobacterium or ‘ballistic’ transformation) Confirm introduced DNA and expression of foregin protein in plant What is included in the recombinant DNA? On/Off switch Gene of interest Marker gene Environment contaminantion via gene flow Contamination of food supply Secondary metabolite – inctroduct allerginiicty or toxicity

Slide5: 

Plant Products Over 120 pharmaceutical products currently in use are derived from plants. Mainly from tropical forest species Plant derived pharmaceuticals (non-GE)

Slide6: 

Industrial products proteins enzymes modified starches fats oils waxes plastics Pharmaceuticals recombinant human proteins Therapeutic proteins enzymes Antibodies (plantibodies) vaccines 2. Plant-made pharmaceuticals and industrial products (GE) Plant-derived pharmaceuticals (non-GE) Plant Products

Slide7: 

Strategies for ‘Molecular Farming’ Plant gene expression strategies Transient transformation Stable transformation Chloroplast transformation

Slide8: 

Strategies for ‘Molecular Farming’ Plant gene expression strategies Protein quantity and preservation Whole plant Target specific tissues (e.g. seed, root) 2. Location of trans-gene expression?

Slide9: 

Strategies for ‘Molecular Farming’ Plant gene expression system 2. Location of trans-gene expression? 3. Selection of plant species and characteristics Mode of reproduction – self/outcrossing Yield, harvest, production, processing

Slide10: 

Advantages Cost reduction Stability Safety Why use plants? Disadvantages Environment contamination Food supply contamination Health safety concerns

Slide11: 

Cellulase for production of alcohols Avidin – medical diagnostics b-glycoprotein – biomedical diagnostics Plant-derived plastic: Production of polyhydroxyalkanoate (PHA) To date, more costly than fuel-based plastic Examples of Industrial PMPs

Slide12: 

High wax esters Jojoba seeds - gene has been isolated and expressed in Arabidopsis (49-70% oil present as wax) Astaxanthin red pigment in shell-fish. used in aquaculture Compounds to increase flavor and fragrances Examples of Industrial PMPs

Slide13: 

Edible vaccines Advantages: Administered Directly no purification required no hazards assoc. w/injections Production may be grown locally, where needed most no transportation costs Naturally stored Plant-made Vaccines

Slide14: 

Examples of edible vaccines ; pig vaccine in corn, HIV-suppressing protein in spinach, human vaccine for hepatitus B in potato. Plant-made Vaccines

Slide15: 

- Plants can be used to produce monoclonal antibodies Tobacco, corn, potatoes, soy, alfalfa, rice Free from potential contamination of mammalian viruses Examples: cancer, dental caries, herpes simplex virus, respiratory syncytial virus **GE Corn can produce up to 1 kg antibody/acre and can be stored at RT for up to 5 years! Humphreys DP et al. Curr Opin Drug Discover Dev 2001; 4:172-85. Plantibodies

Slide16: 

Therapeutic proteins Blood substitutes – human hemoglobin Proteins to treat diseases CF, HIV, Hypertension, Hepatitis B…..many others **To date, no plant-produced pharmaceuticals are commercially available. Plant made Pharmaceuticals

Slide17: 

LEX System™ Lemna, (duckweed) Dental Caries: CaroRx™ Colds due to Rhinovirus: RhinoRx™ Drug-induced Alopecia: DoxoRx™ Planet Biotechnology Biomass biorefinery based on switchgrass. Produce PHAs in green tissue plants for fuel generation. Current ‘Pharm’ Companies

Slide18: 

Trangenic tobacco PMPs and non-protein substances (flavors and fragrances, medicinals, and natural insecticides) Kentucky Tobacco Research and Development Center Trangenic tobacco GeneWare® Current ‘Pharm’ Companies Controlled Pharming Ventures In collaboration w/Purdue Transgenic corn Converted limestone mine facility

Slide19: 

Transgenic corn Trypsin and Aprotinin Prodigene Current ‘Pharm’ Companies Ventria Bioscience Transgenic rice Lactoferrin Lysozyme

Slide20: 

Genetically engineered Arabidopsis plants can sequester arsenic from the soil. (Dhankher et al. 2002 Nature Biotechnology) Immunogenicity in human of an edible vaccine for hepatitis B (Thanavala et al., 2005. PNAS) Examples of Current Research Expression of single-chain antibodies in transgenic plants. (Galeffi et al., 2005 Vaccine) Plant based HIV-1 vaccine candidate: Tat protein produced in spinach. (Karasev et al. 2005 Vaccine) Plant-derived vaccines against diarrheal diseases. (Tacket. 2005 Vaccine)

Slide21: 

Environment contamination Gene flow via pollen Non-target species near field sites e.g. butterflies, bees, etc Food supply contamination Accident, intentional, gene flow Health safety concerns Non-target organ responses Side-effects Allergenicity Risks and Concerns

Slide22: 

U.S. Regulatory System (existing regulations) Field Testing -permits -notifications Determination of non-regulated status Food safety Feed safety Pesticide and herbicide registration USDA FDA EPA

Slide23: 

Breakdown of Regulatory System: Prodigene Incident 2002 2001 : Field trails of GE corn producing pig vaccine were planted in IA and NB. 2002: USDA discovered “volunteer” corn plants in fields in both IA and NE. Soy was already planted in NE site. $500,000 fine + $3 million to buy/destroy contaminated soy

Slide24: 

USDA Response to Incident Revised regulations so that they were distinct from commodity crops: Designated equipment must be used. At least 5 inspections/yr. Pharm crops must be grown at least 1 mile away from any other fields and planted 28 days before/after surrounding crops

Slide25: 

FDA/USDA Guidance for Industry on Plant-Made Pharmaceuticals Regulations November 2004: Draft Document Other challenges: Industrial hygiene and safety programs Current Evolving Regulations

Slide26: 

www.ucsusa.org ‘Molecular farming’ in the US Since 1995 ~ 300 biopharming plantings USDA has received 16 applications for permits in the last 12 months.

Slide27: 

Concerns: CONTAINMENT – opponents want a guarantee of 0% contamination of the food supply. Full disclosure of field trials, crop, gene, location, etc. Extensive regulatory framework ‘Molecular farming’ opposition

Slide28: 

Physical differences E.g. “purple” maize, GFP Sterility Use male sterile plants Terminator technology? Easily detectable by addition of 'reporter genes' PCR markers (avoid antibiotic resistance markers) Suggested Safeguards for ‘molecular farming’

Slide29: 

4. Chloroplast expression system Increase yield Eliminates potential gene flow Technically difficult (Chlorogen Company) 5. Complete disclosure of DNA sequences 6. Legislate for administration. Suggested Safeguards for ‘molecular farming’

Slide30: 

Use only traditional drug production systems microbial, yeast and fungi mammalian cell culture Use only fully contained production systems: Plant cell cultures Hydroponics (rhizosecretion) Greenhouses Use non-food crops Tobacco, Hemp/Cannabis Alternatives to ‘molecular farming’?

Slide31: 

The expectation is for lower production costs however there is no evidence that pharming will produce cheaper, safe drugs. There are unknown costs associated with containment, litigation and liability, production…..others? Economics