Antigenic variation

Definition

Antigenic variation is the process by which a pathogen alters its surface proteins to evade a host's immune response. This mechanism enables pathogens to persist in the host and cause chronic or recurrent infections.

5 Must Know Facts For Your Next Test

1. Antigenic variation is a key virulence factor in many bacterial and viral pathogens, allowing them to escape immune detection.
2. Pathogens such as Neisseria gonorrhoeae and Trypanosoma brucei utilize antigenic variation to avoid being targeted by antibodies.
3. Antigenic variation can involve changes in protein structure, glycosylation patterns, or expression of different genes encoding surface antigens.
4. This mechanism complicates vaccine development because it makes it difficult to target a stable antigen.
5. In addition to bacteria and viruses, some eukaryotic pathogens like Plasmodium species (malaria parasites) also exhibit antigenic variation.

Review Questions

• How does antigenic variation contribute to the persistence of an infection within a host?
• Name two pathogens that utilize antigenic variation as a virulence factor.
• Why does antigenic variation pose challenges for vaccine development?

Related terms

Virulence Factor: A molecule produced by pathogens that contributes to the pathogenicity of the organism.

Immune Evasion:

Strategies used by pathogens to avoid detection and destruction by the host's immune system.

Surface Antigen: Molecules present on the surface of pathogens that are recognized by the immune system.