TABLE 3.

Molecular markers for species specificity of H9 HA genes

Amino acid positionFunction/locationAmino acid in:
ChickensQuailDucksa
8Signal peptideTT (A)A
129 (109 HA1)Bottom of globular head/pH of fusion?S (T)S, N, R (K)N, R (K)
166 (146 HA1)Adjacent receptor binding siteQQ, HH
337 (317 HA1)−4 position, HA cleavage siteRK, RT, A, V
339 (319 HA1)−2 position, HA cleavage siteSS (N)D, N, G
475 (135 HA2)Viral membrane-interacting residue?KKN
500 (160 HA2)Viral membrane-interacting residue?RRQ
  • a Includes viruses isolated from domestic ducks, shorebirds, and turkeys.