Antigenic drift

Definition

Antigenic drift refers to the gradual accumulation of mutations in the genes encoding viral surface proteins, leading to changes in the antigenic properties of a virus. This process allows viruses, especially RNA viruses, to evade the host immune response, making it harder for the immune system to recognize and respond to the virus over time.

5 Must Know Facts For Your Next Test

1. Antigenic drift is most commonly associated with influenza viruses, where small mutations can lead to seasonal epidemics.
2. The accumulation of mutations during antigenic drift can reduce the effectiveness of vaccines developed against previous strains of the virus.
3. Antigenic drift occurs continuously over time, leading to variations that may escape recognition by pre-existing antibodies.
4. Unlike antigenic shift, which can result in significant changes and new subtypes, antigenic drift involves more subtle changes within the same viral strain.
5. The ability of a virus to undergo antigenic drift contributes to its persistence in populations and its potential for re-emergence.

Review Questions

• How does antigenic drift contribute to the challenges faced in vaccine development for certain viruses?
  • Antigenic drift presents significant challenges for vaccine development because it leads to gradual changes in viral surface proteins. As mutations accumulate, previously developed vaccines may become less effective since they target specific antigens that no longer match those present on circulating virus strains. This necessitates ongoing surveillance and potential updates to vaccines to ensure they remain effective against newly emerged variants.
• Compare and contrast antigenic drift with antigenic shift and explain their implications for viral adaptation.
  • Antigenic drift and antigenic shift are both processes that lead to changes in viral antigens but differ significantly in their mechanisms and outcomes. Antigenic drift involves small, gradual mutations that occur over time within a single strain, leading to minor changes that can help the virus evade immune detection. In contrast, antigenic shift results from genetic reassortment between different viral strains, leading to significant changes and potentially creating a novel subtype. Both processes enhance viral adaptation but through different pathways and with varying impacts on public health.
• Evaluate the role of antigenic drift in the emergence of new viral strains and its impact on global health.
  • Antigenic drift plays a critical role in the emergence of new viral strains by allowing viruses like influenza to subtly alter their antigenic profile over time. This ongoing evolution can lead to seasonal outbreaks and complicate efforts at disease control and prevention. The ability of these viruses to evade existing immunity increases their transmission potential and poses challenges for public health responses, including vaccine effectiveness. Thus, understanding antigenic drift is essential for preparing for future outbreaks and maintaining effective surveillance systems.

Related terms

Mutation: A change in the nucleotide sequence of a genome, which can lead to alterations in protein structure and function.

Antigenic shift: A major change in the antigenic properties of a virus that occurs when two different strains exchange genetic material, often resulting in a new subtype.

Viral evolution: The process by which viruses adapt and change over time through mechanisms like mutation, recombination, and selection.