HIV

• Viruses

  • Viruses are a cellular and very small non living particles that can infect living organisms
  • They are parasitic in nature and must replicate inside the cell to reproduce.
  • They have a variety of shapes and genetic material that can be RNA or DNA
  • How it replicates – viruses enter the cell and uses the cell’s proteins and enzymes to produce viral proteins which assembly into viral particles
• Explain the effects that a destroyed helper T- cell has on a specific

  immune response ?

  Destroyed helper T-cells would contribute to the following:

  • Less Helper T-cells produced
  • Reduce/ no stimulation of B-cells
  • No plasma cells, no antibodies produced
  • Phagocytosis would not be stimulated
  • Weaken immune system -> increase risk of exposure to infectious disease
• Define monoclonal antibodies

  Antibodies are produced by plasma cells which are all clones of one B-cell, hence the name monoclonal (one clone).

  They are useful because they can be produced outside the body and they are reactive with only one type of antigen.
• Production of monoclonal antibodies

  Monoclonal antibodies (mAbs) are produced by introducing an antigen to a mouse and then fusing polyclonal B-cells from the mouse's spleen to rapidly dividing myeloma (tumour) cells.

  A) antibodies

  B) spleen

  C) tumour

  D) hybridoma

  E) antibodies

  
• Use of monoclonal antibodies

  1. To target medication to specific cell types by attaching a therapeutic drug to an antibody (radioimmunotherapy).
  2. Pregnancy testing.
  3. Medical diagnosis by identifying proteins or antigen presence using the ELISA test.
• Radioimmunotherapy

  • Links radioactive atoms to monoclonal antibodies that deliver the radioactivity by being complimentary and only binding to antigens only found on cancer cells.
  • Doctors can concentrate radiation at tumour sites, reducing the amount of radiation that reaches healthy tissue.
  • Doctors can also use it to find tumours that may have spread in the body to target therapy where it is needed.
• Cancer immunotherapy

  A) toxin

  B) active drug

  
• Pregnancy test

  1. hCG is a hormone present in early stages of pregnancy
  2. If pregnant - hCG in urine binds to mobile antibodies which are bound to a coloured bead
  3. The mobile antibodies bound to hCG will then bind to an immobilised antibody to create the first “blue line”
  4. The second line is a control line

  A) early stage of pregnancy

  B) binds to antibodies bound to coloured beads

  C) immobilised antibody to create the first “blue line”

  D) second line is control line

  
• The ELISA test

  • The ELISA test stands for enzyme linked immunosorbent assay.
  • It uses monoclonal antibodies to detect the presence and quantity of a protein.
  • It is very sensitive so can detect very small amounts of a molecule.
  • This technique can be used to detect HIV, as well as drug and allergen tests.
• The ELISA test steps

  1. The substrate to be tested is added to the base of a beaker
  2. Excess is washed off
  3. Antibodies are added (from patient sample). If complimentary it will bind to the substrate.
  4. Excess is washed off
  5. A second monoclonal antibody, complimentary to the first antibody, is added. This antibody is also attached to an enzyme.
  6. Excess is washed off
  7. The substrate for the enzyme, which is colourless, is added.
  8. This substrate produces coloured products in the presence of the enzyme.
• label the ELISA diagram

  A) HIV antigen

  B) plasma

  C) antibody

  D) substrate

  
• ELISA tests indirect and direct

  Direct - this just involves one antibody binding to an antigen – used to look for

  the presence of an antigen in a sample.

  Indirect - this uses multiple antibodies and can be used to look for antibodies

  that are complimentary to a specific antigen in a sample
• Direct ELISA