🦠microbiology review

Antigenic drift

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Antigenic drift is a gradual process of genetic mutation in viruses, leading to minor changes in the surface proteins (antigens) that can help the virus evade the immune system. It is commonly seen in RNA viruses such as influenza.

5 Must Know Facts For Your Next Test

  1. Antigenic drift results from small, random mutations in viral RNA.
  2. It leads to new strains of viruses, requiring periodic updates to vaccines.
  3. This process allows viruses to partially escape immunity developed from previous infections or vaccinations.
  4. Influenza A and B viruses undergo antigenic drift frequently, contributing to seasonal flu outbreaks.
  5. Antigenic drift is different from antigenic shift, which involves major changes due to reassortment of viral genes.

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