Archives of Virology

, Volume 156, Issue 1, pp 37–51 | Cite as

Pathogenicity of two Egyptian H5N1 highly pathogenic avian influenza viruses in domestic ducks

  • J. L. Wasilenko
  • A. M. Arafa
  • A. A. Selim
  • M. K. Hassan
  • M. M. Aly
  • A. Ali
  • S. Nassif
  • E. Elebiary
  • A. Balish
  • A. Klimov
  • D. L. Suarez
  • D. E. Swayne
  • M. J. Pantin-Jackwood
Original Article


Domestic ducks have been implicated in the dissemination and evolution of H5N1 highly pathogenic avian influenza (HPAI) viruses. In this study, two H5N1 HPAI viruses belonging to clade 2.2.1 isolated in Egypt in 2007 and 2008 were analyzed for their pathogenicity in domestic Pekin ducks. Both viruses produced clinical signs and mortality, but the 2008 virus was more virulent, inducing early onset of neurological signs and killing all ducks with a mean death time (MDT) of 4.1 days. The 2007 virus killed 3/8 ducks with a MDT of 7 days. Full-genome sequencing and phylogenetic analysis were used to examine differences in the virus genes that might explain the differences observed in pathogenicity. The genomes differed in 49 amino acids, with most of the differences found in the hemagglutinin protein. This increase in pathogenicity in ducks observed with certain H5N1 HPAI viruses has implications for the control of the disease, since vaccinated ducks infected with highly virulent strains shed viruses for longer periods of time, perpetuating the virus in the environment and increasing the possibility of transmission to susceptible birds.



The authors appreciate the assistance provided by Diane Smith, Ronald Graham and Roger Brock in conducting these studies. The authors also thank the SAA sequencing facility at SEPRL and the FSIS histopathology laboratory at Russell Research Center-USDA for technical assistance. They also thank the Naval Medical Research Unit No. 3 (NAMRU3), Egypt, for help providing one of the viruses. Funding was given by the US Department of Agriculture, ARS, Current Research Information System project #6612-32000-048.

Supplementary material

705_2010_813_MOESM1_ESM.eps (608 kb)
Supplementary material 1 (EPS 607 kb)
705_2010_813_MOESM2_ESM.eps (602 kb)
Supplementary material 2 (EPS 602 kb)
705_2010_813_MOESM3_ESM.eps (611 kb)
Supplementary material 3 (EPS 611 kb)
705_2010_813_MOESM4_ESM.eps (613 kb)
Supplementary material 4 (EPS 612 kb)
705_2010_813_MOESM5_ESM.eps (528 kb)
Supplementary material 5 (EPS 527 kb)
705_2010_813_MOESM6_ESM.eps (609 kb)
Supplementary material 6 (EPS 609 kb)
705_2010_813_MOESM7_ESM.eps (604 kb)
Supplementary material 7 (EPS 603 kb)
705_2010_813_MOESM8_ESM.eps (530 kb)
Supplementary material 8 (EPS 530 kb)
705_2010_813_MOESM9_ESM.eps (595 kb)
Supplementary material 9 (EPS 595 kb)
705_2010_813_MOESM10_ESM.doc (58 kb)
Supplementary material 10 (DOC 58 kb)


  1. 1.
    Aiki-Raji CO, Aguilar PV, Kwon YK, Goetz S, Suarez DL, Jethra AI, Nash O, Adeyefa CA, Adu FD, Swayne D, Basler CF (2008) Phylogenetics and pathogenesis of early avian influenza viruses (H5N1), Nigeria. Emerg Infect Dis 14:1753–1755CrossRefPubMedGoogle Scholar
  2. 2.
    Aly MM, Arafa A, Hassan MK (2008) Epidemiological findings of outbreaks of disease caused by highly pathogenic H5N1 avian influenza virus in poultry in Egypt during 2006. Avian Dis 52:269–277CrossRefPubMedGoogle Scholar
  3. 3.
    Arafa A, Suarez DL, Hassan MK, Aly MM (2010) Phylogenetic analysis of hemagglutinin and neuraminidase genes of highly pathogenic avian influenza H5N1 Egyptian strains isolated from 2006 to 2008 indicates heterogeneity with multiple distinct sublineages. Avian Dis 54:345–349CrossRefPubMedGoogle Scholar
  4. 4.
    Baigent SJ, McCauley JW (2001) Glycosylation of haemagglutinin and stalk-length of neuraminidase combine to regulate the growth of avian influenza viruses in tissue culture. Virus Res 79:177–185CrossRefPubMedGoogle Scholar
  5. 5.
    Beard CW (1970) Avian influenza antibody detection by immunodiffusion. Avian Dis 14:337–341CrossRefPubMedGoogle Scholar
  6. 6.
    Bender C, Hall H, Huang J, Klimov A, Cox N, Hay A, Gregory V, Cameron K, Lim W, Subbarao K (1999) Characterization of the surface proteins of influenza A (H5N1) viruses isolated from humans in 1997–1998. Virology 254:115–123CrossRefPubMedGoogle Scholar
  7. 7.
    Bingham J, Green DJ, Lowther S, Klippel J, Burggraaf S, Anderson DE, Wibawa H, Hoa DM, Long NT, Vu PP, Middleton DJ, Daniels PW (2009) Infection studies with two highly pathogenic avian influenza strains (Vietnamese and Indonesian) in Pekin ducks (Anas platyrhynchos), with particular reference to clinical disease, tissue tropism and viral shedding. Avian Pathol 38:267–278CrossRefPubMedGoogle Scholar
  8. 8.
    Bosch FX, Garten W, Klenk HD, Rott R (1981) Proteolytic cleavage of influenza virus hemagglutinins: primary structure of the connecting peptide between HA1 and HA2 determines proteolytic cleavability and pathogenicity of Avian influenza viruses. Virology 113:725–735CrossRefPubMedGoogle Scholar
  9. 9.
    Brown JD, Stallknecht DE, Beck JR, Suarez DL, Swayne DE (2006) Susceptibility of North American ducks and gulls to H5N1 highly pathogenic avian influenza viruses. Emerg Infect Dis 12:1663–1670PubMedGoogle Scholar
  10. 10.
    Capua I, Alexander DJ (2008) Avian influenza vaccines and vaccination in birds. Vaccine 26(Suppl 4):D70–D73CrossRefPubMedGoogle Scholar
  11. 11.
    Cattoli G, Monne I, Fusaro A, Joannis TM, Lombin LH, Aly MM, Arafa AS, Sturm-Ramirez KM, Couacy-Hymann E, Awuni JA, Batawui KB, Awoume KA, Aplogan GL, Sow A, Ngangnou AC, El Nasri Hamza IM, Gamatie D, Dauphin G, Domenech JM, Capua I (2009) Highly pathogenic avian influenza virus subtype H5N1 in Africa: a comprehensive phylogenetic analysis and molecular characterization of isolates. PLoS One 4:e4842CrossRefPubMedGoogle Scholar
  12. 12.
    Chen GW, Chang SC, Mok CK, Lo YL, Kung YN, Huang JH, Shih YH, Wang JY, Chiang C, Chen CJ, Shih SR (2006) Genomic signatures of human versus avian influenza A viruses. Emerg Infect Dis 12:1353–1360PubMedGoogle Scholar
  13. 13.
    Chen H, Deng G, Li Z, Tian G, Li Y, Jiao P, Zhang L, Liu Z, Webster RG, Yu K (2004) The evolution of H5N1 influenza viruses in ducks in southern China. Proc Natl Acad Sci USA 101:10452–10457CrossRefPubMedGoogle Scholar
  14. 14.
    Conenello GM, Zamarin D, Perrone LA, Tumpey T, Palese P (2007) A single mutation in the PB1–F2 of H5N1 (HK/97) and 1918 influenza A viruses contributes to increased virulence. PLoS Pathog 3:1414–1421CrossRefPubMedGoogle Scholar
  15. 15.
    Craig JV, Dean WF, Havenstein GB, Kruger KK, Nestor KE, Purchase GH, Siegel PB, van Wicklen GL (1999) Guidelines for poultry husbandry. In: Science FoASoFA (ed) Guide for the care and use of agricultural animals in agricultural research and teaching. Savoy, IL, pp 55–66Google Scholar
  16. 16.
    Ducatez MF, Olinger CM, Owoade AA, De Landtsheer S, Ammerlaan W, Niesters HG, Osterhaus AD, Fouchier RA, Muller CP (2006) Avian flu: multiple introductions of H5N1 in Nigeria. Nature 442:37CrossRefPubMedGoogle Scholar
  17. 17.
    Ducatez MF, Olinger CM, Owoade AA, Tarnagda Z, Tahita MC, Sow A, De Landtsheer S, Ammerlaan W, Ouedraogo JB, Osterhaus AD, Fouchier RA, Muller CP (2007) Molecular and antigenic evolution and geographical spread of H5N1 highly pathogenic avian influenza viruses in western Africa. J Gen Virol 88:2297–2306CrossRefPubMedGoogle Scholar
  18. 18.
    FAO (2009) H5N1 HPAI Global Overview. Issue No. 14, August 2009.
  19. 19.
    Felsenstein J (1985) Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39:783–791CrossRefGoogle Scholar
  20. 20.
    Gilbert M, Chaitaweesub P, Parakamawongsa T, Premashthira S, Tiensin T, Kalpravidh W, Wagner H, Slingenbergh J (2006) Free-grazing ducks and highly pathogenic avian influenza, Thailand. Emerg Infect Dis 12:227–234PubMedGoogle Scholar
  21. 21.
    Gilbert M, Xiao X, Pfeiffer DU, Epprecht M, Boles S, Czarnecki C, Chaitaweesub P, Kalpravidh W, Minh PQ, Otte MJ, Martin V, Slingenbergh J (2008) Mapping H5N1 highly pathogenic avian influenza risk in Southeast Asia. Proc Natl Acad Sci USA 105:4769–4774CrossRefPubMedGoogle Scholar
  22. 22.
    Gonzalez S, Ortin J (1999) Distinct regions of influenza virus PB1 polymerase subunit recognize vRNA and cRNA templates. EMBO J 18:3767–3775CrossRefPubMedGoogle Scholar
  23. 23.
    Guionie O, Guillou-Cloarec C, Courtois D, Bougeard BS, Amelot M, Jestin V (2010) Experimental infection of Muscovy ducks with highly pathogenic avian influenza virus (H5N1) belonging to clade 2.2. Avian Dis 54:538–547CrossRefPubMedGoogle Scholar
  24. 24.
    Guo YJ, Krauss S, Senne DA, Mo IP, Lo KS, Xiong XP, Norwood M, Shortridge KF, Webster RG, Guan Y (2000) Characterization of the pathogenicity of members of the newly established H9N2 influenza virus lineages in Asia. Virology 267:279–288CrossRefPubMedGoogle Scholar
  25. 25.
    Ha Y, Stevens DJ, Skehel JJ, Wiley DC (2001) X-ray structures of H5 avian and H9 swine influenza virus hemagglutinins bound to avian and human receptor analogs. Proc Natl Acad Sci USA 98:11181–11186CrossRefPubMedGoogle Scholar
  26. 26.
    Hatta M, Gao P, Halfmann P, Kawaoka Y (2001) Molecular basis for high virulence of Hong Kong H5N1 influenza A viruses. Science 293:1840–1842CrossRefPubMedGoogle Scholar
  27. 27.
    Honda A, Mizumoto K, Ishihama A (1999) Two separate sequences of PB2 subunit constitute the RNA cap-binding site of influenza virus RNA polymerase. Genes Cells 4:475–485CrossRefPubMedGoogle Scholar
  28. 28.
    Hulse-Post DJ, Sturm-Ramirez KM, Humberd J, Seiler P, Govorkova EA, Krauss S, Scholtissek C, Puthavathana P, Buranathai C, Nguyen TD, Long HT, Naipospos TS, Chen H, Ellis TM, Guan Y, Peiris JS, Webster RG (2005) Role of domestic ducks in the propagation and biological evolution of highly pathogenic H5N1 influenza viruses in Asia. Proc Natl Acad Sci USA 102:10682–10687CrossRefPubMedGoogle Scholar
  29. 29.
    Hulse-Post DJ, Franks J, Boyd K, Salomon R, Hoffmann E, Yen HL, Webby RJ, Walker D, Nguyen TD, Webster RG (2007) Molecular changes in the polymerase genes (PA and PB1) associated with high pathogenicity of H5N1 influenza virus in mallard ducks. J Virol 81:8515–8524CrossRefPubMedGoogle Scholar
  30. 30.
    Hulse DJ, Webster RG, Russell RJ, Perez DR (2004) Molecular determinants within the surface proteins involved in the pathogenicity of H5N1 influenza viruses in chickens. J Virol 78:9954–9964CrossRefPubMedGoogle Scholar
  31. 31.
    Ives JA, Carr JA, Mendel DB, Tai CY, Lambkin R, Kelly L, Oxford JS, Hayden FG, Roberts NA (2002) The H274Y mutation in the influenza A/H1N1 neuraminidase active site following oseltamivir phosphate treatment leave virus severely compromised both in vitro and in vivo. Antiviral Res 55:307–317CrossRefPubMedGoogle Scholar
  32. 32.
    Jiao P, Tian G, Li Y, Deng G, Jiang Y, Liu C, Liu W, Bu Z, Kawaoka Y, Chen H (2008) A single-amino-acid substitution in the NS1 protein changes the pathogenicity of H5N1 avian influenza viruses in mice. J Virol 82:1146–1154CrossRefPubMedGoogle Scholar
  33. 33.
    Joannis T, Lombin LH, De Benedictis P, Cattoli G, Capua I (2006) Confirmation of H5N1 avian influenza in Africa. Vet Rec 158:309–310CrossRefPubMedGoogle Scholar
  34. 34.
    Katz JM, Lu X, Tumpey TM, Smith CB, Shaw MW, Subbarao K (2000) Molecular correlates of influenza A H5N1 virus pathogenesis in mice. J Virol 74:10807–10810CrossRefPubMedGoogle Scholar
  35. 35.
    Kaverin NV, Rudneva IA, Ilyushina NA, Varich NL, Lipatov AS, Smirnov YA, Govorkova EA, Gitelman AK, Lvov DK, Webster RG (2002) Structure of antigenic sites on the haemagglutinin molecule of H5 avian influenza virus and phenotypic variation of escape mutants. J Gen Virol 83:2497–2505PubMedGoogle Scholar
  36. 36.
    Kawaoka Y, Nestorowicz A, Alexander DJ, Webster RG (1987) Molecular analyses of the hemagglutinin genes of H5 influenza viruses: origin of a virulent turkey strain. Virology 158:218–227CrossRefPubMedGoogle Scholar
  37. 37.
    Keawcharoen J, van Riel D, van Amerongen G, Bestebroer T, Beyer WE, van Lavieren R, Osterhaus AD, Fouchier RA, Kuiken T (2008) Wild ducks as long-distance vectors of highly pathogenic avian influenza virus (H5N1). Emerg Infect Dis 14:600–607CrossRefPubMedGoogle Scholar
  38. 38.
    Kim JK, Seiler P, Forrest HL, Khalenkov AM, Franks J, Kumar M, Karesh WB, Gilbert M, Sodnomdarjaa R, Douangngeun B, Govorkova EA, Webster RG (2008) Pathogenicity and vaccine efficacy of different clades of Asian H5N1 avian influenza A viruses in domestic ducks. J Virol 82:11374–11382CrossRefPubMedGoogle Scholar
  39. 39.
    Kim JK, Negovetich NJ, Forrest HL, Webster RG (2009) Ducks: the “Trojan horses” of H5N1 influenza. Influenza Other Resp Viruses 3:121–128CrossRefGoogle Scholar
  40. 40.
    Kimura M (1980) A simple method for estimating evolutionary rates of base substitutions through comparative studies of nucleotide sequences. J Mol Evol 16:111–120CrossRefPubMedGoogle Scholar
  41. 41.
    Li KS, Guan Y, Wang J, Smith GJ, Xu KM, Duan L, Rahardjo AP, Puthavathana P, Buranathai C, Nguyen TD, Estoepangestie AT, Chaisingh A, Auewarakul P, Long HT, Hanh NT, Webby RJ, Poon LL, Chen H, Shortridge KF, Yuen KY, Webster RG, Peiris JS (2004) Genesis of a highly pathogenic and potentially pandemic H5N1 influenza virus in eastern Asia. Nature 430:209–213CrossRefPubMedGoogle Scholar
  42. 42.
    Li ML, Rao P, Krug RM (2001) The active sites of the influenza cap-dependent endonuclease are on different polymerase subunits. EMBO J 20:2078–2086CrossRefPubMedGoogle Scholar
  43. 43.
    Li Z, Jiang Y, Jiao P, Wang A, Zhao F, Tian G, Wang X, Yu K, Bu Z, Chen H (2006) The NS1 gene contributes to the virulence of H5N1 avian influenza viruses. J Virol 80:11115–11123CrossRefPubMedGoogle Scholar
  44. 44.
    Lin T, Wang G, Li A, Zhang Q, Wu C, Zhang R, Cai Q, Song W, Yuen KY (2009) The hemagglutinin structure of an avian H1N1 influenza A virus. Virology 392:73–81CrossRefPubMedGoogle Scholar
  45. 45.
    Londt BZ, Nunez A, Banks J, Nili H, Johnson LK, Alexander DJ (2008) Pathogenesis of highly pathogenic avian influenza A/turkey/Turkey/1/2005 H5N1 in Pekin ducks (Anas platyrhynchos) infected experimentally. Avian Pathol 37:619–627CrossRefPubMedGoogle Scholar
  46. 46.
    Long JX, Peng DX, Liu YL, Wu YT, Liu XF (2008) Virulence of H5N1 avian influenza virus enhanced by a 15-nucleotide deletion in the viral nonstructural gene. Virus Genes 36:471–478CrossRefPubMedGoogle Scholar
  47. 47.
    Matrosovich M, Zhou N, Kawaoka Y, Webster R (1999) The surface glycoproteins of H5 influenza viruses isolated from humans, chickens, and wild aquatic birds have distinguishable properties. J Virol 73:1146–1155PubMedGoogle Scholar
  48. 48.
    Mukaigawa J, Nayak DP (1991) Two signals mediate nuclear localization of influenza virus (A/WSN/33) polymerase basic protein 2. J Virol 65:245–253PubMedGoogle Scholar
  49. 49.
    Ohuchi M, Ohuchi R, Feldmann A, Klenk HD (1997) Regulation of receptor binding affinity of influenza virus hemagglutinin by its carbohydrate moiety. J Virol 71:8377–8384PubMedGoogle Scholar
  50. 50.
    OIE (2008) OIE Report Ref: 7012, Report Date: 07/07/2008, Country: Egypt.
  51. 51.
    Owoade AA, Gerloff NA, Ducatez MF, Taiwo JO, Kremer JR, Muller CP (2008) Replacement of sublineages of avian influenza (H5N1) by reassortments, sub-Saharan Africa. Emerg Infect Dis 14:1731–1735CrossRefPubMedGoogle Scholar
  52. 52.
    Pantin-Jackwood MJ, Suarez DL, Spackman E, Swayne DE (2007) Age at infection affects the pathogenicity of Asian highly pathogenic avian influenza H5N1 viruses in ducks. Virus Res 130:151–161CrossRefPubMedGoogle Scholar
  53. 53.
    Pantin-Jackwood MJ, Swayne DE (2009) Pathogenesis and Pathobiology of avian influenza virus infection in birds. Rev Scientifique et Tech (Int Office Epizootics) 28:113–136Google Scholar
  54. 54.
    Perk S, Banet-Noach C, Golender N, Simanov L, Rozenblut E, Nagar S, Pokamunski S, Pirak M, Tendler Y, Garcia M, Panshin A (2007) Molecular characterization of the glycoprotein genes of H5N1 influenza A viruses isolated in Israel and the Gaza Strip during 2006 outbreaks. Virus Genes 35:497–502CrossRefPubMedGoogle Scholar
  55. 55.
    Pfeiffer DU, Minh PQ, Martin V, Epprecht M, Otte MJ (2007) An analysis of the spatial and temporal patterns of highly pathogenic avian influenza occurrence in Vietnam using national surveillance data. Vet J 174:302–309CrossRefPubMedGoogle Scholar
  56. 56.
    Pfeiffer J, Pantin-Jackwood M, To TL, Nguyen T, Suarez DL (2009) Phylogenetic and biological characterization of highly pathogenic H5N1 avian influenza viruses (Vietnam 2005) in chickens and ducks. Virus Res 142:108–120CrossRefPubMedGoogle Scholar
  57. 57.
    Portela A, Digard P (2002) The influenza virus nucleoprotein: a multifunctional RNA-binding protein pivotal to virus replication. J Gen Virol 83:723–734PubMedGoogle Scholar
  58. 58.
    Puthavathana P, Auewarakul P, Charoenying PC, Sangsiriwut K, Pooruk P, Boonnak K, Khanyok R, Thawachsupa P, Kijphati R, Sawanpanyalert P (2005) Molecular characterization of the complete genome of human influenza H5N1 virus isolates from Thailand. J Gen Virol 86:423–433CrossRefPubMedGoogle Scholar
  59. 59.
    Reed LaHM (1938) A simple method of estimating fifty percent endpoints. Am J Hyg 27:493–497Google Scholar
  60. 60.
    Saitou N, Nei M (1987) The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4:406–425PubMedGoogle Scholar
  61. 61.
    Salzberg SL, Kingsford C, Cattoli G, Spiro DJ, Janies DA, Aly MM, Brown IH, Couacy-Hymann E, De Mia GM, Dung do H, Guercio A, Joannis T, Maken Ali AS, Osmani A, Padalino I, Saad MD, Savic V, Sengamalay NA, Yingst S, Zaborsky J, Zorman-Rojs O, Ghedin E, Capua I (2007) Genome analysis linking recent European and African influenza (H5N1) viruses. Emerg Infect Dis 13:713–718PubMedGoogle Scholar
  62. 62.
    Schmidtke M, Zell R, Bauer K, Krumbholz A, Schrader C, Suess J, Wutzler P (2006) Amantadine resistance among porcine H1N1, H1N2, and H3N2 influenza A viruses isolated in Germany between 1981 and 2001. Intervirology 49:286–293CrossRefPubMedGoogle Scholar
  63. 63.
    Seo SH, Hoffmann E, Webster RG (2002) Lethal H5N1 influenza viruses escape host anti-viral cytokine responses. Nat Med 8:950–954CrossRefPubMedGoogle Scholar
  64. 64.
    Shaw M, Cooper L, Xu X, Thompson W, Krauss S, Guan Y, Zhou N, Klimov A, Cox N, Webster R, Lim W, Shortridge K, Subbarao K (2002) Molecular changes associated with the transmission of avian influenza a H5N1 and H9N2 viruses to humans. J Med Virol 66:107–114CrossRefPubMedGoogle Scholar
  65. 65.
    Sims LD (2007) Experience in control of avian influenza in Asia. Dev Biol (Basel) 130:39–43Google Scholar
  66. 66.
    Smith GJ, Naipospos TS, Nguyen TD, de Jong MD, Vijaykrishna D, Usman TB, Hassan SS, Nguyen TV, Dao TV, Bui NA, Leung YH, Cheung CL, Rayner JM, Zhang JX, Zhang LJ, Poon LL, Li KS, Nguyen VC, Hien TT, Farrar J, Webster RG, Chen H, Peiris JS, Guan Y (2006) Evolution and adaptation of H5N1 influenza virus in avian and human hosts in Indonesia and Vietnam. Virology 350:258–268CrossRefPubMedGoogle Scholar
  67. 67.
    Stevens J, Blixt O, Tumpey TM, Taubenberger JK, Paulson JC, Wilson IA (2006) Structure and receptor specificity of the hemagglutinin from an H5N1 influenza virus. Science 312:404–410CrossRefPubMedGoogle Scholar
  68. 68.
    Stevens J, Blixt O, Chen LM, Donis RO, Paulson JC, Wilson IA (2008) Recent avian H5N1 viruses exhibit increased propensity for acquiring human receptor specificity. J Mol Biol 381:1382–1394CrossRefPubMedGoogle Scholar
  69. 69.
    Subbarao EK, London W, Murphy BR (1993) A single amino acid in the PB2 gene of influenza A virus is a determinant of host range. J Virol 67:1761–1764PubMedGoogle Scholar
  70. 70.
    Suzuki H, Saito R, Masuda H, Oshitani H, Sato M, Sato I (2003) Emergence of amantadine-resistant influenza A viruses: epidemiological study. J Infect Chemother 9:195–200CrossRefPubMedGoogle Scholar
  71. 71.
    Swayne DE (2006) Principles for vaccine protection in chickens and domestic waterfowl against avian influenza: emphasis on Asian H5N1 high pathogenicity avian influenza. Ann N Y Acad Sci 1081:174–181CrossRefPubMedGoogle Scholar
  72. 72.
    Swayne DE, Halvorson DA (2008) Influenza. In: Saif YM, Glisson JR, Fadly AM, McDougald LR, Nolan L (eds) Diseases of poultry, 12th edn. Blackwell, Ames, IowaGoogle Scholar
  73. 73.
    Tamura K, Dudley J, Nei M, Kumar S (2007) MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0. Mol Biol Evol 24:1596–1599CrossRefPubMedGoogle Scholar
  74. 74.
    Tang Y, Wu P, Peng D, Wang X, Wan H, Zhang P, Long J, Zhang W, Li Y, Wang W, Zhang X, Liu X (2009) Characterization of duck H5N1 influenza viruses with differing pathogenicity in mallard (Anas platyrhynchos) ducks. Avian Pathol 38:457–467CrossRefPubMedGoogle Scholar
  75. 75.
    Toyoda T, Adyshev DM, Kobayashi M, Iwata A, Ishihama A (1996) Molecular assembly of the influenza virus RNA polymerase: determination of the subunit-subunit contact sites. J Gen Virol 77(Pt 9):2149–2157CrossRefPubMedGoogle Scholar
  76. 76.
    WHO (2008) Toward a unified nomenclature system for highly pathogenic avian influenza virus (H5N1). Emerg Infect Dis 14:e1Google Scholar
  77. 77.
    WHO (2009) Continuing progress towards a unified nomenclature for the highly pathogenic H5N1 avian influenza viruses: divergence of clade 2.2 viruses. Influenza Other Respir Viruses 3:59–62CrossRefGoogle Scholar
  78. 78.
    WHO (2009) H5N1 avian influenza: timeline of major events.
  79. 79.
    Yamada S, Suzuki Y, Suzuki T, Le MQ, Nidom CA, Sakai-Tagawa Y, Muramoto Y, Ito M, Kiso M, Horimoto T, Shinya K, Sawada T, Kiso M, Usui T, Murata T, Lin Y, Hay A, Haire LF, Stevens DJ, Russell RJ, Gamblin SJ, Skehel JJ, Kawaoka Y (2006) Haemagglutinin mutations responsible for the binding of H5N1 influenza A viruses to human-type receptors. Nature 444:378–382CrossRefPubMedGoogle Scholar

Copyright information

© US Government 2010

Authors and Affiliations

  • J. L. Wasilenko
    • 1
  • A. M. Arafa
    • 2
  • A. A. Selim
    • 2
  • M. K. Hassan
    • 2
  • M. M. Aly
    • 2
  • A. Ali
    • 3
  • S. Nassif
    • 3
  • E. Elebiary
    • 3
  • A. Balish
    • 4
  • A. Klimov
    • 4
  • D. L. Suarez
    • 1
  • D. E. Swayne
    • 1
  • M. J. Pantin-Jackwood
    • 1
  1. 1.Exotic and Emerging Avian Viral Diseases Unit, Southeast Poultry Research LaboratoryUnited States Department of Agriculture, Agricultural Research ServiceAthensUSA
  2. 2.National Laboratory for Veterinary Quality Control on Poultry ProductionGizaEgypt
  3. 3.Central Laboratory for Evaluation of Veterinary Biologics (CLEVB)CairoEgypt
  4. 4.Influenza DivisionNational Center for Immunization and Respiratory Diseases, Centers for Disease Control and PreventionAtlantaUSA

Personalised recommendations