Convergent Evolution of Human-Isolated H7N9 Avian Influenza A Viruses. (9th February 2018)

• Record Type: Journal Article
• Authors: Xiang, Dan; Shen, Xuejuan; Pu, Zhiqing; Irwin, David M; Liao, Ming; Shen, Yongyi
• Is Part Of: Journal of infectious diseases. Volume 217:Number 11(2018)
• Page Start: 1699
• Page End: 1707
• Publication Date: 2018-02-09
• Subjects: H7N9 -- convergent evolution -- human infection -- host shift; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiy082
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract : We detected signals of positive selection and parallel evolution in H7N9 avian influenza virus sequences that occurred during the multiple invasions of this virus into humans. These changes likely reflect adaptations of this virus to the new mammalian (human) environment. Abstract: Background: Avian influenza A virus H7N9 has caused 5 epidemic waves of human infections in China since 2013. Avian influenza A viruses may face strong selection to adapt to novel conditions when establishing themselves in humans. In this study, we sought to determine whether adaptive evolution had occurred in human-isolated H7N9 viruses. Methods: We evaluated all available genomes of H7N9 avian influenza A virus. Maximum likelihood trees were separately reconstructed for all 8 genes. Signals of positive selection and convergent evolution were then detected on branches that lead to changes in host tropism (from avian to human). Results: We found that 3 genes had significant signals of positive selection (all of them P < .05). In addition, we detected 34 sites having significant signals for parallel evolution in 8 genes (all of them P < .05), including 7 well-known sites (Q591K, E627K, and D701N in PB2 gene; R156K, V202A, and L244Q in HA; and R289K in NA) that play roles in crossing species barriers for avian influenza A viruses. Conclusion: Our study suggests that, during infection in humans, H7N9 viruses have undergone adaptive evolution to adapt to their new host environment and that the sites where parallel evolution occurred might play roles in crossing species barriers and respond to the new selection pressures arising from their new host environments.