Depending on the specific combination of genetic segments, and notably in the case of a human influenza strain acquiring the Hemagglutinin (HA) and/or Neuraminidase (NA) major surface antigens from animal origin, reassortment events can result in an antigenic shift, defined as the generation of a new virus with antigenic properties drastically different from those of the circulating strains. This evidence concerns the gene XK and influenza.