vaccines

• vaccine: a way of introducing antigens of a dead or weak pathogen into the body to stimulate the production of antibodies and memory cells
• one dose of a vaccine induces a primary immune response
• multiple does of a vaccine can increase the number of antibodies and memory cells in the blood stream through the secondary response
• vaccines are long lasting, as they produce memory cells
• pathogens prepared for viruses are made harmless by:

  • killing
  • weakening
  • purified antigens
  • using inactivated toxins
• attenuated ‘live’ vaccine:

  • bacteria or virus with loe virulence are administered
  • the pathogen will multiply, but only at very low levels
• inactivated ‘dead’ vaccine

  • bacteria or virus re grown in culture and killed using heat or chemicals
  • although the pathogen is dead, it still contains the antigens that can stimulate the immune response
• virus-like particle vaccines:

  • viral proteins derived from the structural proteins of the virus
  • proteins can assemble into particles that resemble the virus, but lack DNA, so can’t replicate