A look at how various pathogens emply antigenic variation to evade the adaptive immune response, including specific examples (such as the 'flu).
Antigenic variation is an immune evasion mechanism employed by numerous pathogens to avoid the host immune response. The goal of this variation is to avoid the adaptive immune response.
One form of antigenic variation occurs across the population of a pathogen, so that people who have previously suffered from one strain are not protected against further infections from different strains of the same pathogen. This is most elegantly employed by the influenzae virus, which has 2 major surface proteins ...
Reviews antigenic variation, a mechanism that some pathogens (including influenza) use to escape the immune system