Additionally, the H5N1 strain NIBRG-14 (a 6:2 reverse genetics reassortment containing HA, with the polybasic cleavage site deleted, and NA from A/Vietnam/1194/2004) and a swine H1N1 influenza isolate were included in the panel, as these strains represent potential pandemic-causing viruses. The gene discussed is XK; the disease is influenza.