TABLE 1.

Affinity of the H5N1 influenza viruses to sialyl substrates

VirusaChanges in HA receptor binding sitebAffinity for sialyl substratec
Fetuinp6′SLp3′SL
HK/03 (E2/E1)S133, N2230.18 ± 0.035.78 ± 0.82c1.05 ± 0.21
VN/04 (E2/E1)S133, S2230.13 ± 0.03>1001.21 ± 0.05
VN/05 (C1/E1)A133, S2230.15 ± 0.08>1000.12 ± 0.02d
TK/06 (E2/E1)S133, N2230.15 ± 0.0610.34 ± 1.40c0.44 ± 0.05
  • a Virus abbreviations: HK/03, A/HK/213/03; VN/04, A/VN/1203/04; VN/05, A/VN/JP36-2/05; TK/06, A/Turkey/65-596/06. Virus passage history is indicated in parentheses after the virus as follows: C, passaged in MDCK cells; E, passaged in embryonated chicken eggs (e.g., E2/E1, virus was passaged twice in embryonated chicken eggs prior to arrival at St. Jude's Children's Research Hospital; it was subsequently passaged once in eggs prior to the experiments).

  • b Changes in conserved residues. H5 numbering was used.

  • c The dissociation constant Kdiss = mean ± standard error × tα,n−1 (μM sialic acid), where tα is Student's coefficient with probability α = 0.95, from four independent experiments. Fetuin possesses both α2,3- and α2,6-linked SA, while p3′SL and p6′SL are synthetic sialosaccharides with α2,3 and α2,6 linkages, respectively.

  • d Significantly different from the value for other viruses (P < 0.05 by analysis of variance).