Highly conserved hemagglutinin peptides of H1N1 influenza virus elicit immune response

In the current study, two highly conserved (> 90%) H1N1 hemagglutinin peptides STDTVDTVLEKNVTVTHSVNL (H1) and KVNSVIEKMNTQFTAVGKEF (H2) containing multiple T-cell epitopes have been assessed for their immunogenic potential in vitro, subjecting peripheral blood mononuclear cells from healthy volunteers to repetitive stimulation of chemically synthesised H1 and H2 peptides, and measuring their interferon (IFN)-γ level (ELISA) and proliferation (MTT assay). Further, these peptides were analysed for their binding affinity with 18 different human leukocyte antigen (HLA) class I and II by means of molecular docking. All seven samples tested for H1- and H2-induced IFN-γ secretion were found to have enhanced IFN-γ production. Six (H1) and five (H2) samples have shown proliferative response compared to unstimulated cells. Peptide-induced IFN-γ secretion and proliferation in healthy samples represent the immunogenic potential of these peptides. Further, molecular docking results reveal that the peptides have comparable binding energy to that of native bound peptide for both HLA classes which indicates that these peptides have the capability to be presented by different HLA molecules required for T-cell response. Hence, these conserved immunogenic hemagglutinin peptides are potential candidates for influenza vaccine development.