Cover Article

Science China Life Sciences

, Volume 56, Issue 6, pp 485-492

Open Access This content is freely available online to anyone, anywhere at any time.

Environmental connections of novel avian-origin H7N9 influenza virus infection and virus adaptation to the human

  • Jun LiAffiliated withHangzhou Center for Disease Control and Prevention
  • , XinFen YuAffiliated withHangzhou Center for Disease Control and Prevention
  • , XiaoYing PuAffiliated withHangzhou Center for Disease Control and Prevention
  • , Li XieAffiliated withHangzhou Center for Disease Control and Prevention
  • , YongXiang SunAffiliated withXiaoshan Center for Disease Control and Prevention
  • , HaiXia XiaoAffiliated withLaboratory of Protein Engineering and Vaccine, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences
  • , FenJuan WangAffiliated withXiaoshan Center for Disease Control and Prevention
  • , Hua DinAffiliated withHangzhou Center for Disease Control and Prevention
  • , Ying WuAffiliated withCAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences
    • , Di LiuAffiliated withCAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of SciencesNetwork Information Center, Institute of Microbiology, Chinese Academy of Sciences
    • , GuoQiu ZhaoAffiliated withHangzhou Center for Disease Control and Prevention
    • , Jun LiuAffiliated withCAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of SciencesNational Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention Email author 
    • , JingCao PanAffiliated withHangzhou Center for Disease Control and Prevention Email author 

Abstract

A novel H7N9 influenza A virus has been discovered as the causative identity of the emerging acute respiratory infection cases in Shanghai, China. This virus has also been identified in cases of infection in the neighboring area Hangzhou City in Zhejiang Province. In this study, epidemiologic, clinical, and virological data from three patients in Hangzhou who were confirmed to be infected by the novel H7N9 influenza A virus were collected and analyzed. Human respiratory specimens and chicken feces from a contacted free market were tested for influenza virus by real-time reverse transcription PCR (RT-PCR) and sequencing. The clinical features of the three cases were similar featured with high fever and severe respiratory symptoms; however, only one of the patients died. A certain degree of diversity was observed among the three Hangzhou viruses sequenced from human samples compared with other reported H7N9 influenza A viruses. The sequences of the novel avian-origin H7N9 influenza viruses from Hangzhou City contained important amino acid substitutions related to human adaptation. One of the Hangzhou viruses had gained a novel amino acid substitution (Q226I) in the receptor binding region of hemagglutinin. More importantly, the virus sequenced from the chicken feces had a 627E substitution in the PB2 protein instead of the mammalian-adapted 627K substitution that was found in the PB2 proteins from the Hangzhou viruses from the three patients. Therefore, the newly-emerging H7N9 virus might be under adaptation pressure that will help it “jump” from avian to human hosts. The significance of these substitutions needs further exploration, with both laboratory experiments and extensive field surveillance.

Keywords

H7N9 influenza A virus human adaptation epidemiology substitution