Immunity and vaccination

• Passive Immunity is the introduction of antibodies into individuals from an outside source.
• Active Immunity results from stimulating the body’s own immune system.
• Natural active immunity results from an individual becoming infected with a disease under normal circumstances.
• Artificial active immunity is established using vaccines. The vaccine induces an immune response in an individual without causing them to experience the symptoms of the disease. If an individual is vaccinated, they are exposed to a weakened or dead version of the pathogen. The antigens are still present, and this stimulates the person to produce their own antibodies in response.
• Features of an effective vaccination program include:

  • Economically available in large enough quantities to immunise most of the population.
  • Minimal side effects
  • Resources to produce, store and transport the vaccine need to be available
  • There must be resources to administer the vaccine
  • It must be possible to immunise the majority of the vulnerable population.
• Herd Immunity occurs when a sufficiently large proportion of the population has vaccinated, to make it difficult for the pathogen to spread.
• Vaccination Ethics:

  For a vaccine to be produced, it often involves the use of animal testing and can cause side effects and long-term harm.

  Vaccines cannot be made compulsory but are only effective if the majority of a population is vaccinated.
• HIV can lead to AIDS.
• HIV has a lipid envelope on the outside with attachment proteins embedded in it. Inside is a protein layer called a capsid that contains two single strands of RNA.
• The presence of reverse transcriptase means that HIV is able to make DNA from RNA. It belongs to a category of viruses called retroviruses.
• HIV is a virus so it can not replicate itself. It uses a complex process to replicate.
• 1. HIV enters the bloodstream and circulates around the body.
• 2. A protein on the HIV binds to a protein called CD4, most frequently found on helper T cells.
• 3. The protein capsid fuses with the cell-surface membrane.
• 4. The RNA and enzymes of HIV enter the helper T cell.
• 5. The HIV reverse transcriptase converts the virus’s RNA into DNA.
• 6. The newly made DNA is moved in to the helper T cells nucleus where it is inserted into the cell’s DNA.
• 7. The HIV DNA in the nucleus creates messenger RNA using the cell’s membranes.
• 8. This mRNA contains the instructions for making new viral proteins and moving the RNA to go in to the new HIV.
• 9. The mRNA passes out of the nucleus through a nuclear pore and uses the cell’s protein synthesis mechanisms to make HIV particles.
• 10. The HIV particles break away from the helper T cell with a piece of is cell-surface membrane surrounding them which forms the lipid envelope.
• HIV causes AIDS by killing or interfering with the functioning of helper T cells which also stops B cells being stimulated so the body can not produce an adequate immune response, making the body more susceptible to other infections.
• ELISA testing - Makes use of antibodies to detect the presence of a protein in a sample and the quantity. It can be used to detect HIV and the pathogens of diseases including tuberculosis and hepatitis.
• Antibiotics are ineffective against HIV and other viruses because they do not have cell walls so there are no metabolic mechanisms or cell structures the antibiotics can disrupt.