Immunology

• How HIV is replicated

  1. Attachment proteins attach to receptors on helper T cell/lymphocyte

  2. Nucleic acid/RNA enters cell

  3. Reverse transcriptase converts RNA to DNA

  4. Viral protein/capsid/enzymes produced

  5. Virus (particles) assembled and released (from cell)
• How an ADC enters and kills the tumour cell

  1. Cell ingests/engulfs the antibody/ADC

  2. Lysosomes fuse with vesicle/phagosome (containing ADC)

  3. Lysozymes breakdown/digest the antibody/ADC to release the drug
• How the human immunodeficiency virus (HIV) is replicated once inside helper T cells (TH cells)


  1. RNA converted into DNA using reverse transcriptase

  2. DNA incorporated/inserted into (helper T cell) DNA/chromosome/genome/nucleus

  3. DNA transcribed into (HIV m)RNA

  4. (HIV mRNA) translated into (new) HIV/viral proteins (for assembly into viral particles)
• How HIV affects the production of antibodies when AIDS develops in a person

  • Less/no antibody produced
  • (Because HIV) destroys helper T cells
  • (So) few/no B cells activated / stimulated
• Role of antibodies in producing a positive result in an ELISA test

  1. (First) antibody binds/attaches /complementary (in shape) to antigen

  2. (Second) antibody with enzyme attached is added

  3. (Second) antibody attaches to antigen

  4. (Substrate/solution added) and colour changes
• Role of antibodies in stimulating phagocytosis

  • Bind to antigen
  • Cause clumping/agglutination