Molecular analysis of avian H7 influenza viruses circulating in Eurasia in 1999-2005: detection of multiple reassortant virus genotypes.
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.
Campitelli
Laura
L
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.
Di Martino
Angela
A
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.
Spagnolo
Domenico
D
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.
Smith
Gavin J D
GJD
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.
Di Trani
Livia
L
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.
Facchini
Marzia
M
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.
De Marco
Maria Alessandra
MA
Department of Veterinary Public Health and Animal Pathology, Faculty of Veterinary Medicine, University of Bologna, Ozzano Emilia (BO), Italy.
Foni
Emanuela
E
Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Parma, Italy.
Chiapponi
Chiara
C
Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Parma, Italy.
Martin
Ana Moreno
AM
Istituto Zooprofilattico Sperimentale of Lombardia and Emilia, Brescia, Italy.
Chen
Honglin
H
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.
Guan
Yi
Y
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.
Delogu
Mauro
M
Department of Veterinary Public Health and Animal Pathology, Faculty of Veterinary Medicine, University of Bologna, Ozzano Emilia (BO), Italy.
Donatelli
Isabella
I
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.
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
D000956:Antigens, Viral; D004279:DNA, Viral; D012367:RNA, Viral