Table 2.

Binding of Neu5Ac and of 3′-SL (Neu5Ac2-3Gal-4Glc) to influenza viruses

VirusAssociation constant (mM−1)a
Neu5Acb3′-SL
Chicken H5N1
 Ck/HK/220/97 (CHO158)1.240
 Ck/HK/258/97 (CHO158)1.330
Human H5N1 HK/156/970.530
Duck viruses
 Dk/HK/205/77 (H5N2)0.315
 Dk/HK/698/79 (H5N2)0.515
 Dk/Bavaria/1/77 (H1N1)0.510
 Mallard/MT/61 (H2N2)0.310
 Dk/Hokkaido/7/82 (H3N8)0.810
Human pandemic strain Aichi/2/68 (H3N2)0.20.2
  • a The association constants of virus complexes with Neu5Ac and 3′SL were determined in a competitive binding assay as described in Materials and Methods.

  • b Free Neu5Ac in solution is a mixture of α- and β-anomers. The β-anomer is not present in the natural sialylglycoconjugates and does not bind to influenza virus (26). Represented here are the values for the α-anomer, which were calculated from the binding data (assuming a 5% content of α-anomer in the mixture).