Vaccination Overview

Vaccination

• Vaccination is a procedure that exposes the immune system to a harmless pathogen variant, stimulating long-term defense.
• Vaccines are harmless pathogen variants that stimulate the immune system's defense mechanisms.
• Effective vaccines have low side effects, protect against natural pathogen variants, stimulate both antibody and cell-mediated responses, create long-term immunological memory, require few doses/boosters, and are inexpensive, stable, and easy to administer.
• Common administration routes are subcutaneous, intramuscular, and intradermal injections; oral vaccines exist for a limited number of diseases.
• Vaccine types include:
  • Killed/inactivated: Harmless, recognizable antigens, need multiple doses.
  • Live attenuated: Long-lasting, fewer boosters, risk of reversion to pathogenicity.
  • Toxoid: Purified toxin elicits an immune response.
  • Genetically modified: Microbial antigen genes create proteins for immunity.
  • Naked DNA: Contains pathogen DNA to trigger cellular immunity.
• Herd immunity occurs when a large portion of a population is vaccinated reducing disease incidence.

Recombinant DNA

• Recombinant DNA is a laboratory-created DNA molecule combining genetic material from different sources.
• Recombinant DNA technology allows scientists to manipulate DNA to create new sequences or desired genes.
• Plasmids are small DNA rings with accessory genes outside the bacterial chromosome.
• Vectors are agents like plasmids or viruses that carry modified genetic material.
• Genes are discrete units of hereditary information encoded in DNA.
• Restriction enzymes cut DNA at specific sequences.
• DNA ligase joins DNA fragments.

Vaccine Development Concerns

• Scientists must ensure vaccine safety and effectiveness.
• Recombinant DNA technology can isolate a pathogen gene, insert it into a vector, and produce a vaccine protein without causing disease.

Vaccine Production Methods

• Scientists use various methods to create vaccines, including but not limited to inactivating the pathogen to create a harmless vaccine.

Bacterial vs. Human DNA

• Bacterial DNA is usually a single circular chromosome in the cytoplasm.
• Human DNA is organized into linear chromosomes within a nucleus.

Importance of Plasmids and Bacterial Cells

• Plasmids, naturally occurring vectors, make introducing foreign DNA into bacteria simple, allowing manipulation and controlled gene replication.

Recombinant DNA Procedure

• Restriction enzymes (scissors) cut DNA at specific sequences.
• Plasmids are cut with the same restriction enzyme, creating openings for insertion.
• The gene of interest is placed into the plasmid.
• DNA ligase (glue) joins the fragments.
• The result is recombinant DNA.

Molecular Tools

• Restriction enzymes cut DNA (scissors).
• DNA ligase joins DNA (glue).

Guidelines for Creating New Plasmids

• Use one restriction enzyme that cuts the plasmid ring and the viral gene. Do not cut too many small fragments. Ensure sticky ends.
• Do not remove more than 20 base pairs.
• Do not interrupt the origin of replication (ori) and antibiotic resistance gene.

Restriction Enzyme Use

• Plasmids and DNA to insert must be cut with the same restriction enzyme to create complementary sticky ends for joining.

HaeIII Usage

• HaeIII is not ideal for recombinant DNA work as it produces blunt ends, hard to join.

Molecular Tools in Lab Activity

• Restriction enzymes & DNA ligase act as molecular scissors and glue.

Edible Vaccines

• Advantages: Easy, affordable and accessible administration.
• Disadvantages: Immune tolerance concerns and efficiency/safety research needed.

Comparing Plasmids

• Restriction digestion and gel electrophoresis can compare the primary vs. engineered plasmid. Observe the number of restriction sites before and after alteration.

Recurring Chickenpox

• Chickenpox can be reactivated from a latent state in the spinal cord later in life, triggering shingles.

Annual Flu Vaccine Need

• Flu viruses constantly mutate, requiring yearly vaccine updates to maintain immune protection.