A novel strain, B/Gifu/2/73, differs from other influenza B viruses in the receptor binding specificities toward sialo-sugar chain linkage.

We reported in a previous paper (1. Xu et al, J. Biochem., 115, 202-207, 1994) that every human influenza B virus isolate determined, including B/Lee/40, B/Setagaya/3/56, B/Tokyo/7/66, B/Kagoshima/1/68, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90, restrictively recognizes lacto-series gangliosides containing Neu5Ac alpha 2-6Gal linkage. We found in this study a novel strain, B/Gifu/2/73, that showed remarkable receptor binding specificities to both Neu5Ac alpha 2-3 Gal and Neu5Ac alpha 2-6Gal linkages of lacto-series gangliosides. The amino acid sequence of the hemagglutinin (HA) in strain B/Gifu/2/73 was compared with that of B/Lee/40, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90. Substitution of His116, Ala121, Arg141, Pro211, His253, and His271 in the HA1 subunit of strain B/Gifu/2/73 for Asn116, Thr121, Gly141, Gln211, Gln253, and Gln271 in the HA1 of the four strains above was found, indicating that these amino acid changes in the HA1 of B/Gifu/2/73 may play an important role in recognition of Neu5Ac alpha 2-3Gal and Neu5Ac alpha 2-6Gal linkages in the receptor sialo-sugar chains.