Identification of oligopeptides mimicking the receptor-binding domain of Hantaan virus envelope glycoprotein from a phage-displayed peptide library

Abstract

Attachment of enveloped viruses to cells is triggered by the receptor-binding domain (RBD) on envelope glycoproteins (GP) binding to receptors located on the cell surface. To date, recognized receptors and RBD of hantaan virus (HTNV) have not been exactly defined. In this study, one monoclonal antibody (MAb) 3G1 possessing high neutralizing activity, which is directed against HTNV envelope glycoprotein G2, was used to determine the crucial motif of RBD. Peptide ligands binding to MAb 3G1 were selected from a 12 amino acid peptide library displayed on filamentous phages. After 3 rounds of selection, the binding capacity between phages and MAb 3G1 was examined byELISA. Afterwards the positive phage clones with high binding activity to MAb 3G1 were chosen and sequenced. The peptide sequences of positive phage clones were compared with that of HTNV 76–118 strain G2. A motif Y/F/WPW(X)HX1–2HY, aligned to the primary sequences of G2 96YPWHTAKCHY105, was identified from the peptide inserts in the 9 positive clones. Positive phages and synthesized peptide containing the motif were bound significantly to virus-susceptible cell (Vero-E6) membranes by ELISA and immunofluorescence assay, respectively. Therefore, the sequence on G2 between amino acid 96 and 105 may be a key motif of HTNV RBD recognized by viral receptors on target cell membranes. Further characterization of the motif would provide useful information in understanding of the cellular entry of HTNV.