DefinitionThis section has been translated automatically.
Antigenic drift refers to slow, continuous and random changes of immunity-forming surface structures (antigens) of pathogenic microorganisms.
General informationThis section has been translated automatically.
An example of this is influenza viruses in which, for example, point mutations occur in the genes that code for haemagglutinin and another surface protein, neuraminidase.
Such mutations, which occur every 2-3 years, mainly alter the protein segments that are important for the binding of neutralizing antibodies. These are only insufficiently effective. Other mutations affect epitopes that are recognized by T cells and in particular by CD8 T cells.
This antigenic drift of the virus leads to the selection of antigenic variants. These can now be attacked less efficiently by the host's immune defenses. The result is a new infection, despite previous illness or vaccination, which is relatively mild (there is usually still a certain cross-reaction with antibodies and T cells that were produced against the earlier variant of the virus) because most people have a certain residual immunity.
