title: Antigenic, genetic, and pathogenic characterization of H5N1 highly pathogenic avian influenza viruses isolated from dead whooper swans (Cygnus cygnus) found in northern Japan in 2008.
abstract: In April and May 2008, whooper swans (Cygnus cygnus) were found dead in Hokkaido in Japan. In this study, an adult whooper swan found dead beside Lake Saroma was pathologically examined and the identified H5N1 influenza virus isolates were genetically and antigenically analyzed. Pathological findings indicate that the swan died of severe congestive edema in the lungs. Phylogenetic analysis of the HA genes of the isolates revealed that they are the progeny viruses of isolates from poultry and wild birds in China, Russia, Korea, and Hong Kong. Antigenic analyses indicated that the viruses are distinguished from the H5N1 viruses isolated from wild birds and poultry before 2007. The chickens vaccinated with A/duck/Hokkaido/Vac-1/2004 (H5N1) survived for 14 days after challenge with A/whooper swan/Hokkaido/1/2008 (H5N1), although a small amount of the challenge virus was recovered from the tissues of the birds. These findings indicate that H5N1 highly pathogenic avian influenza viruses are circulating in wild birds in addition to domestic poultry in Asia and exhibit antigenic variation that may be due to vaccination.
authors.affiliation: Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18 Nishi 9, Kita-ku, Sapporo, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Okamatsu
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Tanaka
authors.forename: Naoki
authors.initials: N
authors.lastname: Yamamoto
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Sakoda
authors.forename: Takashi
authors.initials: T
authors.lastname: Sasaki
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Tsuda
authors.forename: Norikazu
authors.initials: N
authors.lastname: Isoda
authors.forename: Norihide
authors.initials: N
authors.lastname: Kokumai
authors.forename: Ayato
authors.initials: A
authors.lastname: Takada
authors.forename: Takashi
authors.initials: T
authors.lastname: Umemura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kida
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000276:immunology / Q000821:virology; D046090:Anseriformes / Q000276:immunology / Q000821:virology*; D000940:Antigenic Variation; D002642:Chick Embryo; D002645:Chickens; D053124:Influenza A Virus, H5N1 Subtype / Q000145:classification / Q000235:genetics* / Q000276:immunology / Q000472:pathogenicity*; D005585:Influenza in Birds / Q000276:immunology / Q000473:pathology / Q000821:virology*; D007564:Japan; D008168:Lung / Q000473:pathology / Q000821:virology; D008969:Molecular Sequence Data; D010802:Phylogeny; D014774:Virulence