Antigenic Variation

• What is antigenic variation?

  • When some pathogens can change their surface antigens
  • So different antigens are formed due to changes in the genes of a pathogen
• What happens when you are infected for the 2nd time due to mutating pathogens?

  • The memory cells produced from the first infection will not recognise the different antigens
  • The primary response takes time to remove infection so you become ill again
• Why does antigenic variation make the development of vaccines difficult?

  • Pathogens mutate and change their surface antigens
  • So when you're infected for the second time the memory cells will not recognise the different antigens