title: Mammalian adaptive mutations of the PA protein of highly pathogenic avian H5N1 influenza virus.
abstract: Highly pathogenic H5N1 influenza A viruses continue to circulate among avian species and cause sporadic cases of human infection. Therefore, the threat of a pandemic persists. However, the human cases of H5N1 infection have been limited mainly to individuals in close contact with infected poultry. These findings suggest that the H5N1 viruses need to acquire adaptive mutations to gain a replicative advantage in mammalian cells to break through the species barrier. Many amino acid mutations of the polymerase complex have been reported to enhance H5N1 virus growth in mammalian cells; however, the mechanism for H5N1 virus of adaptation to humans remains unclear. Here, we propose that the PA of an H5N1 influenza virus isolated from a human in Vietnam (A/Vietnam/UT36285/2010 [36285]) increased the ability of an avian H5N1 virus (A/chicken/Vietnam/TY31/2005 [Ck/TY31]) to grow in human lung epithelial A549 cells. The five PA amino acid substitutions V44I, V127A, C241Y, A343T, and I573V, which are rare in H5N1 viruses from human and avian sources, enhanced the growth capability of this virus in A549 cells. Moreover, these mutations increased the pathogenicity of the virus in mice, suggesting that they contribute to adaptation to mammalian hosts. Intriguingly, PA-241Y, which 36285 encodes, is conserved in more than 90% of human seasonal H1N1 viruses, suggesting that PA-241Y contributes to virus adaptation to human lung cells and mammalian hosts.
  
  
  OBJECTIVE
  Many amino acid substitutions in highly pathogenic H5N1 avian influenza viruses have been shown to contribute to adaptation to mammalian hosts. However, no naturally isolated H5N1 virus has caused extensive human-to-human transmission, suggesting that additional, as-yet unidentified amino acid mutations are needed for adaptation to humans. Here, we report that five amino acid substitutions in PA (V44I, V127A, C241Y, A343T, and I573V) contribute to the replicative efficiency of H5N1 viruses in human lung cells and to high virulence in mice. These results are helpful for assessing the pandemic risk of isolates and further our understanding of the mechanism of H5N1 virus adaptation to mammalian hosts.
authors: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors: Reina
authors: R
authors: Yamaji
authors: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan shinya@ims.u-tokyo.ac.jp kawaoka@ims.u-tokyo.ac.jp.
authors: Shinya
authors: S
authors: Yamada
authors: National Institute of Hygiene and Epidemiology, Hanoi, Vietnam.
authors: Mai Q
authors: MQ
authors: Le
authors: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors: Mutsumi
authors: M
authors: Ito
authors: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan.
authors: Yuko
authors: Y
authors: Sakai-Tagawa
authors: Division of Virology, Department of Microbiology and Immunology, Institute of Medical Science, University of Tokyo, Tokyo, Japan Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin, USA Department of Special Pathogens, International Research Center for Infectious Diseases, Institute of Medical Science, University of Tokyo, Tokyo, Japan shinya@ims.u-tokyo.ac.jp kawaoka@ims.u-tokyo.ac.jp.
authors: Yoshihiro
authors: Y
authors: Kawaoka
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D004285:Dogs; D057809:HEK293 Cells; D006801:Humans; D053124:Influenza A Virus, H5N1 Subtype / Q000235:genetics* / Q000472:pathogenicity*; D061985:Madin Darby Canine Kidney Cells; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D014744:Vietnam; D014764:Viral Proteins / Q000235:genetics*; D014774:Virulence
chemical_list: C061290:PA protein, influenza viruses; D014764:Viral Proteins; D012324:RNA-Dependent RNA Polymerase
references: Nat Commun. 2014;5:5021
references: 25289523
references: Lancet. 2008 Apr 26;371(9622):1427-34
references: 18400288
references: J Gen Virol. 2012 Mar;93(Pt 3):531-40
references: 22090209
references: J Virol. 2007 May;81(10):5315-24
references: 17344288
references: N Engl J Med. 2005 Sep 29;353(13):1374-85
references: 16192482
references: J Biol Chem. 2011 Oct 7;286(40):34504-13
references: 21816827
references: Nature. 2009 Apr 16;458(7240):914-8
references: 19194459
references: PLoS Pathog. 2008 Feb 8;4(2):e11
references: 18248089
references: Nature. 2009 Apr 16;458(7240):909-13
references: 19194458
references: J Virol. 2009 Dec;83(23):12325-35
references: 19793828
references: Nat Commun. 2011 Jan 18;2:156
references: 21245837
references: J Gen Virol. 1994 Jan;75 ( Pt 1):29-36
references: 8113737
references: J Virol. 2004 Sep;78(17):9144-53
references: 15308710
references: PLoS One. 2012;7(3):e33383
references: 22438920
references: J Virol. 2010 May;84(9):4395-406
references: 20181719
references: N Engl J Med. 2005 Jan 27;352(4):333-40
references: 15668219
references: J Virol. 2012 Feb;86(3):1750-7
references: 22090127
references: PLoS Pathog. 2007 Oct 5;3(10):1374-9
references: 17922570
references: J Virol. 2013 Mar;87(5):2660-72
references: 23255810
references: Antimicrob Agents Chemother. 1994 Dec;38(12):2827-37
references: 7695269
references: PLoS Pathog. 2010;6(8):e1001034
references: 20700447
references: J Gen Virol. 2007 Feb;88(Pt 2):547-53
references: 17251573
references: J Virol. 2011 Jan;85(1):357-65
references: 20962098
references: J Virol. 2007 Aug;81(16):8515-24
references: 17553873
references: PLoS Pathog. 2009 Jan;5(1):e1000252
references: 19119420
references: J Gen Virol. 2010 May;91(Pt 5):1284-9
references: 20016035
references: J Virol. 2010 Sep;84(17):8607-16
references: 20592084
references: N Engl J Med. 2008 Jan 17;358(3):261-73
references: 18199865
references: J Virol. 2011 Dec;85(24):13271-7
references: 21994462
references: Virus Res. 2011 Jun;158(1-2):124-9
references: 21458512
references: Proc Natl Acad Sci U S A. 1999 Aug 3;96(16):9345-50
references: 10430945
references: Virology. 2010 May 25;401(1):96-106
references: 20211480
references: J Gen Virol. 2011 Jul;92(Pt 7):1645-9
references: 21471324
references: Virol J. 2013;10:243
references: 23886034
references: J Virol. 2005 Sep;79(18):12058-64
references: 16140781
references: Proc Natl Acad Sci U S A. 2001 Jun 5;98(12):6883-8
references: 11371620
references: J Infect Dis. 2012 Jan 15;205(2):262-71
references: 22102733
references: J Virol. 1996 Mar;70(3):1905-11
references: 8627716
references: Nat Struct Mol Biol. 2007 Mar;14(3):229-33
references: 17310249
references: Nat Commun. 2012;3:802
references: 22549831