Since 1997,highly pathogenic avian influenza (HPAI) H5N1 viruses have caused serious outbreaks in poultry and markets,In human,overall mortality in HPAI H5N1 infection exceeds 60％,but human to human transmission is limited and has been only reported within family members[7,8].There is much concern as to whether H5N1 can enhance its transmission among humans through genetic variation.Further,there is an urgent need to discover the potential mutations in viral proteins that are responsible for inter-human transmission.
