Fig. 1

Identification and location of the desired amino acid residues. a Identification of the conserved amino acids in the second receptor binding site by sequence alignment using BioEdit 7 software. Residues in yellow indicate completely conserved amino acids in the HN protein of NDV, hPIV1–4, PIV5 and SV. Residues in orange show the previously characterized partially conserved amino acid R516, which was pointed out that its side chain was involved in the interaction with thiosialoside in a previous study [10]. The numbers correspond to the amino acid sequences of NDV HN. b The location of the desired amino acid residues. The homology modelling was generated by PyMOL 2.0 based on the crystal structure of NDV HN (PDB ID: 1USR), which shows the structure of the globular head domain of the NDV HN monomer. The residues are shown in space-filling mode