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.

Mechanistic Insight into Bunyavirus-Induced Membrane Fusion from Structure-Function Analyses of the Hantavirus Envelope Glycoprotein Gc

“…There are also data on Gc residues that affect binding of neutralizing antibodies for various other hantaviruses. Although often such epitopes are conformational and cannot be mimicked by peptides, the epitope of the neutralizing murine Mabs 3G1 and 3D8 [39] against Hantaan virus have been respectively mapped by peptide scanning to residues 96–105 [40] and 242–248 [41]. The 3G1 epitope thus maps to the bc loop and largely overlaps with that of scFv A5, whereas the 3D8 epitope maps to the i strand, at the opposite side (Fig 1C).…”

Identification of a novel B-cell epitope of Hantaan virus glycoprotein recognized by neutralizing 3D8 monoclonal antibody

“…However, little research has been done on the binding sites of 3G1 and 3D8 mAbs. So far only one epitope 96 YPWHTAKCHY 105 recognized by 3G1 mAb has been identified by the phage-displayed peptide library (Lü et al , 2009). The binding sites of 3D8 mAb remain unclear.…”

“…Some neutralizing mAbs directed against the receptor-binding domain (RBD) can block the interaction between RBD and the receptors for the virus. The epitopes binding to these neutralizing mAbs might be mimicking crucial motifs of RBD (Lü et al , 2009). However, whether the RBD overlaps the epitopes of the 3D8 mAb needs further investigations.…”