TABLE 2

Amino acids at NA residues of A(H7N9) viruses that are critical for MAb binding

Residue no.aAmino acids located in NA of:
AH/13Viruses isolated in 2016–2017b
247SS (4.7), P (94.7), P/L (0.6)c
250GG (100)
251PP (100)
253DD (100)
334NN (99.4), D (0.6)
345NN (97), I (2.4), N/I (0.6)
368SS (100)
370AA (89.3), T (10.1), I (0.6)
371SS (100)
373SS (100)
400NN (100)
434KK (100)
  • a N9 numbering is based on the G70C NA.

  • b A total of 169 full-length NA sequences of human A(H7N9) viruses isolated between 1 October 2016 and 20 October 2017 (GISAID) were compared with the sequence of AH/13 at 12 antigenically critical residues. Numbers in parentheses represent the percentages of A(H7N9) isolates bearing each residue in NA.

  • c A mixed sequence was present at positions 247 and 345.