How are Antibodies Produced by Biotechnology?

Antibodies are produced by biotechnology through the isolation, cloning, and expression of antibody genes in host cells, followed by harvesting and purification. Here's a more detailed breakdown:

Steps in Antibody Production via Biotechnology

1. Gene Isolation and Cloning:

   • Researchers identify and isolate the genes that encode the desired antibody. These genes typically include those for both the heavy and light chains of the antibody.
   • These genes are then cloned into specifically designed expression vectors. These vectors are circular DNA molecules that contain the necessary genetic elements to drive the production of the antibody protein within a host cell.

2. Introduction into Host Cells (Transformation/Transfection):

   • The expression vectors containing the antibody genes are introduced into host cells. This process can be achieved using various methods, including:
     • Transformation: Commonly used for bacterial host cells.
     • Transfection: Commonly used for mammalian host cells.
   • The chosen host cell acts as a miniature factory, replicating the vector and producing the antibody protein. Commonly used host cells include:
     • Bacteria (e.g., E. coli): Offers rapid growth and cost-effective production but may lack the ability to perform complex post-translational modifications required for some antibodies.
     • Yeast (e.g., Pichia pastoris): Provides a balance between cost-effectiveness and the ability to perform some post-translational modifications.
     • Mammalian cells (e.g., CHO cells, NS0 cells): Capable of producing antibodies with correct folding and glycosylation, which are crucial for their function. Glycosylation is the addition of sugar molecules to the protein.

3. Antibody Production and Secretion:

   • Once inside the host cells, the antibody genes are transcribed and translated, resulting in the production of the antibody protein.
   • In some cases, the antibodies are secreted from the host cells into the surrounding medium.

4. Harvesting and Purification:

   • The antibodies are harvested from the culture medium or from within the host cells (depending on the expression system).
   • Various purification techniques are used to isolate and purify the antibodies. These techniques often include:
     • Affinity chromatography: This highly selective method uses a ligand that specifically binds to the antibody of interest, allowing it to be separated from other proteins. Protein A or Protein G are common affinity ligands.
     • Ion exchange chromatography: Separates proteins based on their charge.
     • Size exclusion chromatography: Separates proteins based on their size.

Examples of Antibody Production

• Monoclonal Antibody Production: Hybridoma technology, while not strictly biotechnology, paved the way for recombinant antibody production. Nowadays, monoclonal antibodies are frequently produced by engineering a stable CHO cell line to express the antibody of interest.

• Recombinant Antibody Fragments: Techniques allow the production of antibody fragments like Fab or scFv (single-chain variable fragment). These smaller fragments retain the antigen-binding specificity of the parent antibody but offer advantages such as improved tissue penetration.

Benefits of Biotechnology in Antibody Production

• Scalability: Biotechnology enables the production of large quantities of antibodies.
• Specificity: Recombinant technologies allow precise control over antibody specificity and affinity.
• Purity: Purification techniques result in highly pure antibody preparations.
• Humanization: Antibody sequences can be engineered to resemble human antibodies, reducing the risk of immune reactions.

In summary, biotechnology allows for the production of antibodies with high specificity, purity, and in large quantities, through gene cloning, expression in host cells, and sophisticated purification methods.