title: Panorama phylogenetic diversity and distribution of Type A influenza virus.
abstract: BACKGROUND
  Type A influenza virus is one of important pathogens of various animals, including humans, pigs, horses, marine mammals and birds. Currently, the viral type has been classified into 16 hemagglutinin and 9 neuraminidase subtypes, but the phylogenetic diversity and distribution within the viral type largely remain unclear from the whole view.
  
  
  RESULTS
  The panorama phylogenetic trees of influenza A viruses were calculated with representative sequences selected from approximately 23,000 candidates available in GenBank using web servers in NCBI and the software MEGA 4.0. Lineages and sublineages were classified according to genetic distances, topology of the phylogenetic trees and distributions of the viruses in hosts, regions and time.
  
  
  CONCLUSIONS
  Here, two panorama phylogenetic trees of type A influenza virus covering all the 16 hemagglutinin subtypes and 9 neuraminidase subtypes, respectively, were generated. The trees provided us whole views and some novel information to recognize influenza A viruses including that some subtypes of avian influenza viruses are more complicated than Eurasian and North American lineages as we thought in the past. They also provide us a framework to generalize the history and explore the future of the viral circulation and evolution in different kinds of hosts. In addition, a simple and comprehensive nomenclature system for the dozens of lineages and sublineages identified within the viral type was proposed, which if universally accepted, will facilitate communications on the viral evolution, ecology and epidemiology.
authors.affiliation: The Laboratory of Animal Epidemiological Surveillance, China Animal Health & Epidemiology Center, Qingdao, China.
authors.forename: Shuo
authors.initials: S
authors.lastname: Liu
authors.forename: Kang
authors.initials: K
authors.lastname: Ji
authors.forename: Jiming
authors.initials: J
authors.lastname: Chen
authors.forename: Di
authors.initials: D
authors.lastname: Tai
authors.forename: Wenming
authors.initials: W
authors.lastname: Jiang
authors.forename: Guangyu
authors.initials: G
authors.lastname: Hou
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Jinping
authors.initials: J
authors.lastname: Li
authors.forename: Baoxu
authors.initials: B
authors.lastname: Huang