Week 11 Flashcards
What is an overview of current plant derived pharmaceuticals?
Morphine and its derivatives are mainly extracted from poppies by the ton.
Vinblastine and vincristine (anti-cancer drugs) are isolated from the leaves of the Madagascar periwinkle plant.
Artemisinin (anti-malarial) is extracted from the plant Artemisia annua, sweet wormwood
What is an overview of the molecules looked for by the pharmaceutical industry?
METABOLITES (SMALL MOLECULES) AND THE PHARMACEUTICAL INDUSTRY IS LOOKING FOR ALTERNATIVE METHODS OF PRODUCTION.
What exmaples of protein-based pharmaeutical molecules could plants be used to make?
Vaccines, particularly virus-like particles (VLPs).
Antibodies for immunotherapy (cancer treatments, passive
immunisation)
Enzymes for enzyme replacement therapies (e.g. Gaucher’s disease).
What are the advantages of using plants to manufactoring pharmaceuticla proteins?
Produce large biomass
Require minimal inputs
Keep themselves sterile
Have no problem of contamination with animal pathogens
Possibility of edible vaccines?
How can you use plants for protein expression?
Possibility arose from developments in 1980s regarding Agrobacterium-mediated transformation
Followed by the development of transient methods based on the use of plant virus-based vectors and agroinfiltration in the 1990s
What are the categories for plant host for protein farming?
Whole food plant
Whole non-food plant
Unusual plants
What is an overview of whole food plant for protein farming?
e.g. potato, soya, maize
Low risk from plant contaminants
What is an overview of whole non-food plant for protein farming?
e.g. tobacco, Arabidopsis
Low risk of entering food chain
What is an overview of unusual plants for protein farming?
(Duckweed, moss, algae)
Might allow adaptation of traditional microorganism culture techniques
What is an overview of containment when working with plants?
Physical e.g. in containment greenhouses, tissue culture vessels. Problems of expense.
Biological e.g. chloroplast transformation to prevent pollen transfer, use of disabled viral vectors
What is an overview of the different types of stable transformation?
Nuclear transformation – Standard method: genetically modify genome in cell nucleus
Plastid transformation – Modify chloroplast genome, allows better containment, high yield – but a prokaryotic environment
What are the advantages of stable transformation?
Introduced sequence is heritable and true-breeding
(homozygous) lines of plants can be created
Site of expression can be controlled by use of tissue-specific promoters, with no limit on complexity
Well-established technology for creation of plants with different phenotypes such as herbicide resistance
What is an example of a promoter used to maximsie expression levels?
35S promoter from Cauliflower Mosaic Virus. Can be constitutive, tissuespecific
What is an example of a 5’ UTR used to maximsie expression levels?
Cowpea Mosaic Virus RNA-2 5’ UTR with or without translantionenhancing mutation
What is an example of a coding sequence and optional used to maximsie expression levels?
Coding sequence for a protein, fusion protein, synthetic protein
Optional: tag or signal peptide (Nor C- terminal)
What is an example of a 3’ UTR used to maximsie expression levels?
Nopaline synthase (Nos) gene terminator from Agrobacterium tumefaciens TDNA – evolved for plant cell use
What is an early attemot at an edible vaccine?
EDIBLE VACCINE AGAINST NOROVIRUS
What is an overview of the Norovirus?
Small RNA virus which causes intestinal infection
Results in diarrhoea and vomiting particularly in winter and when people are in close contact
58kDa coat protein will self-assemble into particles in heterologous system
Particles will raise antibodies when administered to mice
What is an overview of the pharmancy/lab experince with norovirus?
Cannot grow virus in culture
No vaccine or treatment available
How did they make a norovirus in plants?
Make cassette containing CaMV 35S promoter, translational enhancer, sequence of NV coat protein (CP) and nos terminator
Transform tobacco and potato
Examine expression and aggregation state of CP in regenerated plants
What is an overview the results of a norovirus vaccine in plants?
Expression detected in plants
Expressed protein forms NV particles
What is an overview the mice and human trials of a norovirus vaccine in plants?
Plant-derived particles stimulate mucosal immune response when orally administered to mice
When peeled raw potatoes were fed to human volunteers increased levels of NV antibodies were found
What are the problems with edible norovirus vaccines?
How do you test whether it works?? (As it cant be cultured)
Do you want to eat raw potatoes????
Problems in controlling the dose.
How effective is antibody production in plants?
As early as 1989, it was shown that functional IgG molecules can be synthesised in plants.
IgGs consist of 2 heavy (H) and 2 light (L) chains linked by disulphide bonds
What is an potential advantage of antibody production in plants?
Such molecules have large number of uses in both diagnostics and treatments.
Normally produced in mammalian cells but very expensive
What is an overview of EU sixth framework producing antibodies in plants?
Ran from 2004 to 2012 and involved 33 partners including academic institutions, SMEs and large industry.
Target was the IgG molecule 2G12 which has broad anti=HIV neutralising activity in vitro.
Potential use as a topical microbicide to prevent HIV transmission
What is an overview of the making of antibodies in plants to help reduce transmission of plants?
Transformed with plasmid containing LC and HC genes, linked to selectable and visible markers
High expressers used to generate production lines
Assayed for 2G12 (HIV antibody)
What is the outcome of producing antibodies in plants to help reduce transmission of plants?
Antibodies were substantially similar in physical proterties to mammalian CHO derieved excpet glycan structuture
Indentical in terms of functional properties in all test and efficacious in HIV neutralisation assays
Can be scaled up am pass GMP compliancy
What is an overview of 2G12 production and purification?
GMP compliant downstream processsing achieved
Preclincal toxicology tests approved
Clinical trial plant approved
Phase 1 clinical trials
What is an overview of phase 1 trial plant 2G12 roadmap?
Started in 2008
November 2008, clinical trial application to MHRA
March 2009 initiate clinical trial
Concluded in 2011
What did the 2G12 plant production show?
Plants can produce materials to clinical trial standards
Development of methods to make and extract antibodies
Difficult to devise methods demostrating efficacy
And ability to scale up production
Why is 2G12 plant production not needed?
HIV is now far more treatable by anti-retroviral drugs