This study analyzed the genetic evolution of neuraminidases(NAs)of influenza A subtype N9 viruses with the aim of determining the genetic origin of the novel avian A/H7N9 influenza virus.The NA sequences of influenza A subtype N9 viruses available from NCBI were used to construct a phylogenetic tree using the programs ClustalX 2.0and MEGA 6.0.This analysis indicated that the novel avian A/H7N9 influenza virus is located in the modern Eurasian phylogenetic cluster.This cluster was then further analyzed by es...