One way flu viruses change is called “antigenic drift.” Drift consists of small changes (or mutations) in the genes of influenza viruses that can lead to changes in the surface proteins of the virus, HA (hemagglutinin) and NA (neuraminidase).
What is antigenic shift and antigenic drift in influenza?
Influenza strains are constantly mutating. A small change to the genetic makeup of influenza strains is referred to as antigenic drift, while a major change is called antigenic shift.
How does antigenic drift occur?
Antigenic drift: A subtle change in the surface glycoprotein (either hemagglutinin or neuraminidase) caused by a point mutation or deletion in the viral gene. This results in a new strain that requires yearly reformulation of the seasonal influenza vaccine.
When does antigenic drift occur?
Antigenic drift is a natural process whereby mutations (mistakes) occur during replication in the genes encoding antigens that produce alterations in the way they appear to the immune system (antigenic changes) (Figure 1).
Which type of mutation occur of antigenic drift?
20 Antigenic drift is caused by point mutations in the HA and NA genes that are driven by immune pressure and the infidelity inherent in the replication of RNA genomes.