PLANTIBODIES – “PLENTY ROLES” !!!
The term “plantibodies” was created to describe the products of plants that have been genetically engineered to express antibodies and antibody fragments in planta, with many applications. Antibodies were first produced in tobacco plants, Smith, 1986. Plants are being used in this technology as antibody factories, using their endomembrane and secretory systems to produce large amounts of clinically viable proteins which can later be purified from the plant issues. The purified antibodies have many possible applications, for example, as diagnostic tools, in immunochromatography or in medical therapy.
The prerequisites for plantibody production are:-
Ø Cloned genes encoding specific antibodies
Ø Effective regulatory signals for gene expression in the target plant
Ø Selection procedures for the plants
Plants offer several advantages over other systems for the production of antibodies. They are:-
1) Protein production in plants is cheaper than using fermentation systems. 2) Large-scale production of plants and plant parts such as seeds, is well established 3) Plant storage organs, such as seeds and tubers, can serve as storage systems for the antibodies. 4) Processing of plant material for extraction of food components is widely used. 5) Purification of antibodies is simplified where the plant is a normal human food, since the likelihood of hazardous contaminants is reduced. 6) No contaminated virus or organisms occur in plants that could be transmitted to people. 7) Plants can produce antibodies in large amounts and in stable form through targeting expression to specific compartments in the cell, such as chloroplasts or endoplasmic reticulum.
1)TOXIN-SMELLING FOOD WRAP DEVELOPED: The developers of a Canadian-made, bio-chemical plastic wrap which can generate an image or message over any contaminated food product, called Biowrap, and created by Toxin Alert, a Toronto-area company, the plastic wrap uses a protein-based, anti-body detection system to measure the level of toxins in food. This antibody attracts the pathogens that cause 90 percent of all food poisoning — listeria, E. coli O157:H7, salmonella and campylobacter. The resulting reaction then triggers a vegetable-based dye molded into the wrap in the shape of an X, or any other symbol or word warning.
2) TREATMENT OF DENTAL CARIES: CaroRx™ Planet produced the world’s first clinically tested Plantibody, CaroRx™. It binds specifically to Streptococcus mutans, the bacteria that cause tooth decay, and prevents the bacteria from adhering to teeth. CaroRx™ is currently undergoing Phase II U.S. clinical trials under a U.S. FDA-approved Investigational New Drug (IND) application. The first step in the use of CaroRx™ is to professionally clean the teeth with a commonly used oral antiseptic, and is immediately followed by applying CaroRx™ to the teeth several times over a two-week period. No further treatments are required for 6 months to 1 year. In a published clinical trial the Plantibody was compared to the IgG antibody from which it was derived (mouse Guy’s 13 IgG).
3) IN MAMMALS: JIC’s George Lomonossoff and colleagues in Spain and Italy have succeeded in making a plant produce antibodies which provide piglets with immunity to a transmissible gastroenteritis virus (TGEV) when supplied orally. They have engineered Cowpea Mosaic Virus (CPMV) to produce antibody derivatives which can neutralise TGEV. CPMV infects the leaves of the cowpea plant but is non-infectious to animals. On infection with the modified virus, the host plant accumulates high levels of the antibody derivative. Feeding crude plant extract in the piglets’ milk protects them against intestinal TGEV infection. Furthermore, there is also a significant decrease in the amount of virus in the lungs. Similar systems could therefore be used as methods for producing passive immunization against other diseases. The virus that causes Severe Acute Respiratory Syndrome (SARS) is similar to TGEV; the viral vector system could be used to quickly generate large amounts of material to provide immediate protection to healthcare workers.
4)IN PLANTS: Tobacco engineered to express ScFv`s against the Beet necrotic yellow vein virus gave partial protection to the virus. Full length anti- TMV antibodies gave decreased viral necrotic lesions. ScFv`s engineered against artichoke mottled crinkle virus gave decreased infection and delayed symptoms.
FEW MORE….. The availability of genetically modified plant-derived pharmaceuticals is growing. In 2006, there were a number of clinical trials in humans using such materials. For example: • A gastric lipase produced from maize is being evaluated in a phase II trial for the treatment of cystic fibrosis • A drug for the treatment of traveller’s diarrhoea from maize is in phase I • A hepatitis B vaccine from potato is now in phase I Furthermore, in February 2006 the US Food and Drug Administration approved a new vaccine for the treatment of Newcastle disease in poultry from non-nicotine plant cells.
REFERENCES: · ENCYLOPEDIA OF APPLIED PLANT SCIENCES – Volume 1 A-Gro Edited by – Thomas, Murphy, Murray · PLANT BIOTECHNOLOGY- JOURNAL 6(4) 623-631 · FORUM- A FOODTECH CYBER MAGAZINE · PLANET BIOTECHNOLOGY INC. · FOOD&DRINK WEEKLY