title: Interspecies transmission of an H7N3 influenza virus from wild birds to intensively reared domestic poultry in Italy.
abstract: Since the "bird flu" incident in Hong Kong SAR in 1997, several studies have highlighted the substantial role of domestic birds, such as turkeys and chickens, in the ecology of influenza A viruses. Even if recent evidence suggests that chickens can maintain several influenza serotypes, avian influenza viruses (AIVs) circulating in domestic species are believed to be introduced each time from the wild bird reservoir. However, so far the direct precursor of influenza viruses from domestic birds has never been identified. In this report, we describe the antigenic and genetic characterization of the surface proteins of H7N3 viruses isolated from wild ducks in Italy in 2001 in comparison to H7N3 strains that circulated in Italian turkeys in 2002-2003. The wild and domestic avian strains appeared strictly related at both phenotypic and genetic level: homology percentages in seven of their genes were comprised between 99.8% (for PB2) and 99.1% (for M), and their NA genes differed mainly because of a 23-aminoacid deletion in the NA stalk. Outside this region of the molecule, the NAs of the two virus groups showed 99% similarity. These findings indicate that turkey H7N3 viruses were derived "in toto" from avian influenza strains circulating in wild waterfowl 1 year earlier, and represent an important step towards the comprehension of the mechanisms leading to interspecies transmission and emergence of potentially pandemic influenza viruses.
authors.affiliation: Department of Virology, Istituto Superiore Sanita', Rome, Italy. campitel@iss.it
authors.forename: Laura
authors.initials: L
authors.lastname: Campitelli
authors.forename: Elvira
authors.initials: E
authors.lastname: Mogavero
authors.forename: Maria Alessandra
authors.initials: MA
authors.lastname: De Marco
authors.forename: Mauro
authors.initials: M
authors.lastname: Delogu
authors.forename: Simona
authors.initials: S
authors.lastname: Puzelli
authors.forename: Fabiola
authors.initials: F
authors.lastname: Frezza
authors.forename: Marzia
authors.initials: M
authors.lastname: Facchini
authors.forename: Chiara
authors.initials: C
authors.lastname: Chiapponi
authors.forename: Emanuela
authors.initials: E
authors.lastname: Foni
authors.forename: Paolo
authors.initials: P
authors.lastname: Cordioli
authors.forename: Richard
authors.initials: R
authors.lastname: Webby
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Barigazzi
authors.forename: Robert G
authors.initials: RG
authors.lastname: Webster
authors.forename: Isabella
authors.initials: I
authors.lastname: Donatelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000835:Animals, Wild / Q000821:virology; D001715:Bird Diseases / Q000635:transmission* / Q000821:virology; D004372:Ducks / Q000821:virology*; D019143:Evolution, Molecular; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D009980:Influenza A virus / Q000235:genetics / Q000302:isolation & purification*; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology; D007558:Italy; D008969:Molecular Sequence Data; D009439:Neuraminidase; D010802:Phylogeny; D011201:Poultry Diseases / Q000635:transmission* / Q000821:virology; D014422:Turkeys / Q000821:virology*; D014764:Viral Proteins
chemical_list: D019267:Hemagglutinin Glycoproteins, Influenza Virus; D014764:Viral Proteins; C487630:NA protein, influenza A virus; D009439:Neuraminidase