active/passive immunity

• types of immunity:

  • active
  • passive
• vaccine - an attenuated pathogen with antigens is injected into the body
• vaccines stimulate the production of antibodies and memory cells
• doses of vaccines:

  • one dose = induces primary immune response
  • multiple doses = increases number of antibodies and memory cells through secondary immune response
• how pathogens prepared for vaccines:

  • killed but antigens left unaffected
  • attenuated
  • purified antigens removed from pathogen
  • using inactivated toxins - harmless but trigger same immune response
• active immunity:

  • antibodies made by own immune response after being exposed to antigens
  • natural -> pathogen with antigens enters body naturally
  • artificial -> vaccine introduces antigens
  • long term -> memory cells produced
• passive immunity:

  • antibodies made by a different organism is given to own body
  • natural -> baby receives antibodies through placenta
  • artificial -> antibodies injected to destroy toxins
  • short term -> no memory cells produced + antibodies break down after response
• antigenic variability - different strains of a pathogen will have different antigens on the surface
• antigenic variability:

  if antigens are different:

  • memory cells do not recognise the antigens
  • so memory cells not activated
  • antibodies made previously are not complementary
  • so body must undergo primary immune response = symptoms