title: Molecular analysis of avian H7 influenza viruses circulating in Eurasia in 1999-2005: detection of multiple reassortant virus genotypes.
abstract: Avian influenza infections by high and low pathogenicity H7 influenza viruses have caused several outbreaks in European poultry in recent years, also resulting in human infections. Although in some cases the source of H7 strains from domestic poultry was shown to be the viruses circulating in the wild bird reservoir, a thorough characterization of the entire genome of H7 viruses from both wild and domestic Eurasian birds, and their evolutionary relationships, has not been conducted. In our study, we have analysed low pathogenicity H7 influenza strains isolated from wild and domestic ducks in Italy and southern China and compared them with those from reared terrestrial poultry such as chicken and turkey. Phylogenetic analysis demonstrated that the H7 haemagglutinin genes were all closely related to each other, whereas the remaining genes could be divided into two or more phylogenetic groups. Almost each year different H7 reassortant viruses were identified and in at least two different years more than one H7 genotype co-circulated. A recent precursor in wild waterfowl was identified for most of the gene segments of terrestrial poultry viruses. Our data suggest that reassortment allows avian influenza viruses, in their natural reservoir, to increase their genetic diversity. In turn this might help avian influenza viruses colonize a wider range of hosts, including domestic poultry.
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Laura
authors: L
authors: Campitelli
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Angela
authors: A
authors: Di Martino
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Domenico
authors: D
authors: Spagnolo
authors: State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong SAR.
authors: Gavin J D
authors: GJD
authors: Smith
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Livia
authors: L
authors: Di Trani
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Marzia
authors: M
authors: Facchini
authors: Department of Veterinary Public Health and Animal Pathology, Faculty of Veterinary Medicine, University of Bologna, Ozzano Emilia (BO), Italy.
authors: Maria Alessandra
authors: MA
authors: De Marco
authors: Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Parma, Italy.
authors: Emanuela
authors: E
authors: Foni
authors: Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Parma, Italy.
authors: Chiara
authors: C
authors: Chiapponi
authors: Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Brescia, Italy.
authors: Ana Moreno
authors: AM
authors: Martin
authors: State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong SAR.
authors: Honglin
authors: H
authors: Chen
authors: State Key Laboratory of Emerging Infectious Diseases, Department of Microbiology, The University of Hong Kong, Faculty of Medicine Building, 21 Sassoon Road, Pokfulam, Hong Kong SAR.
authors: Yi
authors: Y
authors: Guan
authors: Department of Veterinary Public Health and Animal Pathology, Faculty of Veterinary Medicine, University of Bologna, Ozzano Emilia (BO), Italy.
authors: Mauro
authors: M
authors: Delogu
authors: Department of Infectious, Parasitic and Immune-Mediated Diseases and Department of Food Safety and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Isabella
authors: I
authors: Donatelli
mesh_terms: D000818:Animals; D000956:Antigens, Viral / Q000032:analysis; D001208:Asia; D001483:Base Sequence; D001715:Bird Diseases / Q000821:virology*; D001717:Birds; D004279:DNA, Viral / Q000235:genetics; D005060:Europe; D005814:Genes, Viral; D006801:Humans; D053126:Influenza A Virus, H7N7 Subtype / Q000145:classification / Q000235:genetics*; D005585:Influenza in Birds / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D011200:Poultry; D011201:Poultry Diseases / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics
chemical_list: D000956:Antigens, Viral; D004279:DNA, Viral; D012367:RNA, Viral