Protective Immunity Against Homologous and Heterologous Influenza Virus Lethal Challenge by Immunization with New Recombinant Chimeric HA2-M2e Fusion Protein in BALB/C Mice

Influenza is an acute and highly contagious respiratory disease. The error prone RNA polymerase and segmented nature of the influenza A virus genome allow antigenic drift and shift, respectively. Therefore, most influenza vaccines are inefficient along time and against different viral subtypes. In this study, for the first time, protection properties of a new recombinant fusion of HA2 and M2e peptides originated from influenza virus A/Brisbane/59/2007-like (H1N1) in BALB/c mice model were investigated. After immunization of the BALB/c mice, the protection property of fusion peptide was determined by a neutralizing assay test. For further study, mice were lethal challenged by the (mouse adapted, A/PR8/34 [H1N1]) and heterologous (mouse adapted, A/Brisbane/10/2007 [H3N2]) influenza virus subtypes. Then, the lung viral titers, body weight, and survival rate of the immunized mice were monitored. The results showed that immunization by the M2e-HA2 recombinant fusion peptide provides strong protection against homologous challenge and an infirm protection against heterologous. These protections against homologous and heterologous influenza A virus challenges meant the universal nature of these recombinant peptides in an immunity manner against influenza A virus. However, more studies are needed to optimize this recombinant construction, and this experiment recommends HA2-M2e fusion peptide as a universal influenza A vaccine candidate.