Biotechnology and Genetic Engineering

Plasmids and Bacterial Gene Transfer

• Functionality of Plasmids

  • Plasmids serve as a method for horizontal gene transfer among bacteria, allowing traits not present in chromosomal DNA to be shared.
  • They can carry genes that are advantageous, such as those coding for enzymes that provide resistance to antibiotics (e.g., penicillin, ampicillin).

• Mechanism of Transfer

  • When bacteria containing certain plasmids die, their plasmids are liberated into the environment.
  • Neighboring bacteria can uptake these plasmids and gain the encoded traits.

Genetic Engineering with Plasmids

• Using Restriction Enzymes

  • Genetic engineers manipulate plasmids by isolating them in a solution with restriction enzymes to cleave specific DNA segments.
  • Desired gene segments can be inserted, with the use of repair enzymes, which join these segments at their sticky ends, creating recombined plasmids.

• Transformation Process

  • New plasmids containing inserted genes are introduced to bacterial cultures under conditions favorable for uptake through their cell wall and membrane.
  • Not all bacteria absorb the plasmids; thus, a selective method is employed using antibiotics (e.g., ampicillin, amoxicillin).
  • Only bacteria that successfully incorporated the antibiotic resistance genes from the plasmids thrive in the selective culture, allowing for the propagation of bacteria that express desirable traits, such as insulin or growth hormone production.

Gene Insertion in Eukaryotes

• Methods Overview

  • Insertion of DNA into eukaryotic cell nuclei can be performed via two primary methods: vector methods and vectorless methods.

• Vectorless Method: Electroporation

  • This technique does not depend on an intermediary organism to transfer DNA between species, allowing direct delivery into target cells.

• Vector Method

  • Typically involves using a vector (often a virus) to deliver DNA into cells for therapeutic purposes.

Biopharmaceuticals: Examples and Applications

• Monoclonal Antibodies Production

  • Monoclonal antibodies are produced by injecting an antigen into an animal, which then generates antibodies.
  • B cells that produce these antibodies are harvested and fused with fast-growing tumor cells to create hybridomas that can be cultured in large amounts.

• Gene Therapy

  • Gene therapy is employed to treat diseases by delivering therapeutic genes using vectors.
  • Example: Luxturna, a gene therapy product that uses a viral vector to deliver a functional copy of a gene to treat certain genetic disorders (specifically, mutations causing vision loss).

Immune System Function and Vaccines

• Immune Response

  • The immune system recognizes and responds to pathogens through various types of white blood cells, notably through antibody production by B cells.
  • Antibodies bind specifically to pathogens, neutralizing or marking them for destruction.

• Vaccination Mechanism

  • Vaccines stimulate the immune system by introducing weakened or inactivated parts of pathogens (like proteins or sugars) to elicit an immune response without causing disease.
  • This process results in memory cells that allow for a rapid and effective response to future infections by the same pathogen.

Modern Vaccine Technologies

• mRNA Vaccines
  • Some vaccine candidates for diseases such as COVID-19 use mRNA technology, incorporating the genetic code for key viral components (like the spike protein) to instruct host cells to produce the target protein.
  • This prompts the body to generate a corresponding immune response, including the production of antibodies.

Gene Therapy and Genetic Engineering Products

• Delivery Vector

  • Often, a virus serves as a vector, helping to deliver genes into an individual’s cells, which can correct genetic defects or deficiencies.

• Recombinant Proteins

  • Recombinant proteins such as insulin, human growth hormone, and clotting factors (e.g., Factor VIII for hemophilia) can be produced by inserting the respective genes into bacterial hosts for mass production.

Monoclonal Antibodies Characteristics

• Structure

  • Monoclonal antibodies consist of four polypeptide chains (two heavy and two light chains) with specific regions for binding antigens.
  • Antigen-binding fragments (Fab) are crucial for recognizing and binding to target antigens.

• Types of Monoclonal Antibodies

  • Starting with murine (mouse) antibodies - those ending with “-omab” are fully mouse-derived.
  • Chimeric antibodies (e.g., ending with “-ximab”) are partly human and partly mouse.
  • Humanized antibodies (ending with “-zumab”) have a majority human sequence with minimal mouse components.
  • Fully human antibodies (ending with “-umab”) are entirely human-derived.

• Biosimilars

  • Biosimilars are products that are highly similar but not identical to FDA-approved biologics due to variability in biological production.
  • Interchangeable products are biosimilars that can be substituted for the original without physician intervention, ensuring effectiveness and safety.

Safety and Regulatory Considerations

• Safety Monitoring
  • Continuous assessment of immune responses and safety are crucial during therapy with biopharmaceutical products.
  • Understanding how these products function is essential for patient management and safety assessment, especially in biopharmaceutical applications.