Table 1

Amino acid mutations detected in HA and NA during passage of a duck virus in quaila

VirusAmino acid at position:
P7TDI(3) L(2)N(3) K(2)ENANDSESQΔ67–83I
P10TD(3) G(2)I(2) L(3)N(2) K(3)E(3) K(2)N(3) S(2)A(1) D(4)NDS(2) P(3)E(3) G(2)SQΔ67–83I
P15TD(3) N(2)LKE(3) K(2)NDN(3) D(2)DPGS- (3) Δ39–45(2)Q(3) P(2)Δ67–83I(3) V(2)
P19TdDLKEN(4) S(1)DN(1) D(4)DPGS- (1) Δ39–45(4)Q(1) P(4)Δ67–83I(1) V(4)
  • a Parent virus and viruses passaged in quail were plaque purified in MDCK cells, and the HA and NA genes of five clones for each virus were sequenced. The amino acid changes are shaded. NA, N2 numbering system; HA, H3 numbering system. The numbers in parentheses indicate the numbers of clones that possessed each amino acid out of the five clones sequenced.

  • b After 19 passages, eight amino acid changes accumulated in HA.

  • c A 17-amino-acid deletion in the NA stalk was detected at passage 7 and a 7-amino-acid deletion in the stalk at passage 15, resulting in an amino acid substitution at residue 46.

  • d P19T clones 1, 2, 3, and 5: HA, I3L, N54K, A144D, N159D, N188D, S227P, E325G, and G4S(HA2); NA, Δ39–45, Q46P, Δ67–83, I215I. P19T clone 4: HA, I3L, N54K, A144D, N137S, N188D, S227P, E325G, and G4S(HA2); NA, Δ67–83.