Currently, a new trend in development of vaccines against influenza with broader spectrum of efficacy is focused on conserved antigens of influenza virus. The HA2 glycopolypeptide (HA2 gp) is one of conserved antigens, potentially suitable as immunogens inducing cross-protection against influenza. We selected two distinct domains of HA2 gp originating from influenza A virus (IAV) of H3 subtype for induction of antiviral immune response: the ectodomain (EHA2) comprising aa 23-185 and the fusion peptide (FP) comprising N-terminal aa 1-38. BALB/c mice were immunized with three doses of EHA2 and FP, respectively, and subsequently challenged with 2 LD50 of IAV of homologous (H3) or heterologous (H7) HA subtype. Both peptides induced significant antibody response and protected mice against the lethal infection. The most efficient protection was achieved with EHA2 against homologous virus.
Keywords: influenza A virus; cross-protection; HA2 glycopolypeptide; HA2 ectodomain; fusion peptide; mice; vaccine.