Influenza A viruses are negative strand RNA viruses with a segmented genome that belong to the family of orthomyx-oviridae. Both influenza A and B viruses can infect humans and cause annual influenza epidemics which result in significant mobidity and mortality worldwide.
There are 16 hemagglutinin (HA) and 9 neuraminidase(NA) subtypes of the influenza A virus that infect a wide variety of species [1]. The introduction of avian virus
genes into the human population can happen at any time and may give rise to a new pandemic. There is even the
possibility of a direct infection of humans by avian viruses,
as evidenced by the emergence of the highly pathogenic
avian influenza viruses ofthe H5N1 subtype that were
capable of infecting and killing humans