Three mutations switch H7N9 influenza to human-type receptor specificity
Glycan binding analyses of Sh2 H7N9 mutant HAs, V186N G226S (A) and V186N N224K G228S (B). The mean signal and standard error were calculated from six independent replicates on both the PAA (left column) and the sialoside array (right column). Tissue binding to either chicken or human tracheal sections is observed by HRP-staining (right column). In the PAA array, white open circles represent α2–3 linked sialylated di-LacNAc (3’SLNLN), black closed circles represent α2–6 linked sialylated di-LacNAc (6’SLNLN), and non-sialylated di-LacNAc (LNLN) are represented in asterisks. In the sialoside array α2–3 linked sialosides are shown in white bars (glycans 11 to 79 on the x axis) and α2–6 linked sialosides in black (glycans 80 to 135). Glycans 1 to 10 are non-sialylated controls (see also S1 Table). The sialoside array, ELISA-like assay and tissue binding experiments shown are representative of three independent assays performed with different batches of HA proteins.