Plants produce antibodies by being genetically engineered to express the necessary protein components, often the heavy and light chains, which are then assembled within the plant cells.
Genetic Engineering for Antibody Production
Producing antibodies in plants involves introducing the genes that code for the antibody's protein chains into the plant's genome. Antibodies, typically found in animals, are complex proteins composed of heavy and light chains. Plants naturally do not produce these proteins. To make them, scientists modify plants using genetic engineering techniques.
The Process: Creating Transgenic Plants
The process often involves these key steps:
- Gene Isolation: The genes encoding the specific antibody's heavy and light chains are identified and isolated.
- Vector Construction: These genes are inserted into a suitable DNA vector, often derived from Agrobacterium tumefaciens, a bacterium that can naturally transfer DNA into plant cells.
- Plant Transformation: The vector is used to introduce the antibody genes into plant cells. This can be done by Agrobacterium-mediated transformation or other methods like gene gun technology.
- Selection: Plants that have successfully integrated the antibody genes into their DNA (transgenic plants) are selected, typically using antibiotic or herbicide resistance markers included in the vector.
- Regeneration: Whole plants are regenerated from the transformed cells.
Assembling the Antibody
Once the genes are in the plant, the plant's cellular machinery reads the genes and produces the corresponding heavy and light protein chains. For a functional antibody, both chains must be present and assemble correctly.
A common method for achieving the expression of both chains, as highlighted by researchers, is through breeding:
- Separate Expression: Scientists can create different lines of transgenic plants – one line engineered to produce the antibody's heavy chain and another line engineered to produce the antibody's light chain.
- Crossing Plants: Plants highly expressing each heavy or light chain can be selected and crossed to generate transgenic lines expressing both heavy and light chains.
This crossing approach ensures that the offspring inherit the genes for both chains from their parents, allowing the plant to produce and assemble the complete antibody molecule.
Advantages of Plant Production (Molecular Farming)
Producing antibodies in plants, a field known as molecular farming, offers several advantages:
- Scalability: Plants can be grown in large quantities relatively easily, allowing for scalable antibody production.
- Cost-Effectiveness: Compared to mammalian cell culture, plant cultivation can be less expensive.
- Safety: Plants pose a lower risk of contamination by human or animal pathogens compared to animal cell systems.
- Glycosylation: Plants can perform post-translational modifications like glycosylation (adding sugar molecules), which are important for antibody function and stability. As mentioned in the reference, the crossing approach can be used to express multiple antibodies and antigens with glycomodification.
Summary of Production Steps
| Step | Description | Outcome |
|---|---|---|
| Gene Introduction | Genes for antibody heavy and light chains are introduced into plant cells. | Transgenic plant cells with antibody genes |
| Plant Regeneration | Whole plants are grown from transformed cells. | Transgenic plants |
| Separate Chain Lines | Develop parent lines expressing high levels of either heavy or light chains. | Parent plants (Heavy Chain Expresser, Light Chain Expresser) |
| Plant Crossing | Plants highly expressing each heavy or light chain can be selected and crossed to generate transgenic lines expressing both heavy and light chains. | Offspring plants expressing both chains & assembling antibodies |
| Antibody Extraction | Antibodies are extracted and purified from the plant biomass. | Purified plant-produced antibodies |
This process allows plants to serve as bio-factories for producing therapeutic or diagnostic antibodies.
