Influenza viruses are important pathogens responsible for flu epidemics and pandemics. The socio-economic impact of seasonal flu is very significant and the rapid rate of virus evolution necessitates the development of new vaccines every year. Another major challenge is the emergence of novel strains that are highly pathogenic for humans. Examples include H7N9 and H5N1 (emerged from birds) which have mortality rates of up to 30% and 60%, respectively. Research is underway to develop of a universal flu vaccine that would provide long-lasting protection and be effective against emergent...