Reconstructed H3N2 influenza virus predicted from influenza vaccine strains improved cross-protective immunity in mice

Hemagglutinin (HA) protein of influenza virus is a core antigen protein which induces protective antibody in hosts. But HA genes mutate rapidly. Every year, World Health Organization (WHO) selects representative influenza virus strains from the influenza centers worldwide for virus vaccine production. So, the selected influenza vaccine strains, can partly respond to antigen drifts of circulating influenza virus, especially the reconstructed H3N2 which induces the cross reaction. It is reported here using the Immune Epitope Database and the reverse genetic method on how to produce reassortant influenza virus based on the changes of B and D antigenic regions (B antigenic region: 156-160aa,187-198aa; D antigenic region:167-182aa, 201-215aa) of HA protein of seasonal influenza H3N2 vaccine strains over twenty years. In a mouse model, the attenuated reassortant viruses induced neutralization antibodies, cross-reactive T-cell responses, and were protective against different lethal influenza virus challenge. So, through the analysis of the antigenic regions of HA using computer and software methods, the reconstructed rB/D influenza virus mostly induced cross protection in mouse model. Key words: influenza, vaccine strains, antigen epitope, cross-protective.