A method of treating or preventing H5N1 influenza by administering to a person in need thereof a pharmacologically effective amount of 5-acetamido-4-guanidino-9-O-hexanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid, 5-acetamido-4-guanidino-9-O-decanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid, 5-acetamido-4-guanidino-9-O-dodecanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid or 5-acetamido-4-guanidino-9-O-tetradecanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid. A method of preventing H5N1 influenza by administering to a person in need thereof a pharmacologically effective amount of 5-acetamido-4-guanidino-9-O-octanoyl-2,3,4,5-tetradeoxy-7-O-methyl-D-glycero-D-galacto-non-2-enopyranosoic acid.
