Phylogenetic and evolutionary analysis of influenza A H7N9 virus

Muhammed Babakir-Mina, Salvatore Dimonte, Alessandra Lo Presti, Eleonora Cella, Carlo Federico Perno, Marco Ciotti, Massimo Ciccozzi

Research output: Contribution to journalArticlepeer-review


Recently, human infections with the novel avian-origin influenza A H7N9 virus have been reported from various provinces in China. Human infections with avian influenza A viruses are rare and may cause a wide spectrum of clinical symptoms. This is the first time that human infection with a low pathogenic avian influenza A virus has been associated with a fatal outcome. Here, a phylogenetic and positive selective pressure analysis of haemagglutin (HA), neuraminidase (NA), and matrix protein (MP) genes of the novel reassortant H7N9 virus was carried out. The analysis showed that both structural genes of this reassortant virus likely originated from Euro-Asiatic birds, while NA was more likely to have originated from South Korean birds. The Bayesian phylogenetic tree of the MP showed a main clade and an outside cluster including four sequences from China. The United States and Guatemala classical H7N9-isolates appeared homogeneous and clustered together, although they are distinct from other classical Euro-Asiatic and novel H7N9 viruses. Selective pressure analysis did not reveal any site under statistically significant positive selective pressure in any of the three genes analyzed. Unknown certain intermediate hosts involved might be implicated, so extensive global surveillance and bird-to-person transmission should be closely considered in the future.

Original languageEnglish
Pages (from-to)369-376
Number of pages8
JournalNew Microbiologica
Issue number3
Publication statusPublished - 2014


  • Avian flu outbreak
  • Novel influenza virus
  • Pandemic
  • Phylogenetic analysis
  • Re-assortment
  • Selective pressure analysis

ASJC Scopus subject areas

  • Microbiology (medical)


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