title: Low-Pathogenic Influenza A Viruses in North American Diving Ducks Contribute to the Emergence of a Novel Highly Pathogenic Influenza A(H7N8) Virus.
abstract: Introductions of low-pathogenic avian influenza (LPAI) viruses of subtypes H5 and H7 into poultry from wild birds have the potential to mutate to highly pathogenic avian influenza (HPAI) viruses, but such viruses' origins are often unclear. In January 2016, a novel H7N8 HPAI virus caused an outbreak in turkeys in Indiana, USA. To determine the virus's origin, we sequenced the genomes of 441 wild-bird origin influenza A viruses (IAVs) from North America and subjected them to evolutionary analyses. The results showed that the H7N8 LPAI virus most likely circulated among diving ducks in the Mississippi flyway during autumn 2015 and was subsequently introduced to Indiana turkeys, in which it evolved high pathogenicity. Preceding the outbreak, an isolate with six gene segments (PB2, PB1, PA, HA, NA, and NS) sharing >99% sequence identity with those of H7N8 turkey isolates was recovered from a diving duck sampled in Kentucky, USA. H4N8 IAVs from other diving ducks possessed five H7N8-like gene segments (PB2, PB1, NA, MP, and NS; >98% sequence identity). Our findings suggest that viral gene constellations circulating among diving ducks can contribute to the emergence of IAVs that affect poultry. Therefore, diving ducks may serve an important and understudied role in the maintenance, diversification, and transmission of IAVs in the wild-bird reservoir.IMPORTANCEIn January 2016, a novel H7N8 HPAI virus caused a disease outbreak in turkeys in Indiana, USA. To determine the origin of this virus, we sequenced and analyzed 441 wild-bird origin influenza virus strains isolated from wild birds inhabiting North America. We found that the H7N8 LPAI virus most likely circulated among diving ducks in the Mississippi flyway during autumn 2015 and was subsequently introduced to Indiana turkeys, in which it evolved high pathogenicity. Our results suggest that viral gene constellations circulating among diving ducks can contribute to the emergence of IAVs that affect poultry. Therefore, diving ducks may play an important and understudied role in the maintenance, diversification, and transmission of IAVs in the wild-bird reservoir. Our study also highlights the importance of a coordinated, systematic, and collaborative surveillance for IAVs in both poultry and wild-bird populations.
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA.
authors.forename: Yifei
authors.initials: Y
authors.lastname: Xu
authors.affiliation: U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA aramey@usgs.gov wan@cvm.msstate.edu.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Ramey
authors.affiliation: Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio, USA.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Bowman
authors.affiliation: National Wildlife Disease Program, Wildlife Services, Animal and Plant Health Inspection Service, U.S. Department of Agriculture, Fort Collins, Colorado, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: DeLiberto
authors.affiliation: National Veterinary Services Laboratories, Veterinary Services, U.S. Department of Agriculture, Ames, Iowa, USA.
authors.forename: Mary L
authors.initials: ML
authors.lastname: Killian
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Krauss
authors.affiliation: Department of Veterinary Preventive Medicine, Ohio State University, Columbus, Ohio, USA.
authors.forename: Jacqueline M
authors.initials: JM
authors.lastname: Nolting
authors.affiliation: National Veterinary Services Laboratories, Veterinary Services, U.S. Department of Agriculture, Ames, Iowa, USA.
authors.forename: Mia Kim
authors.initials: MK
authors.lastname: Torchetti
authors.affiliation: U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA.
authors.forename: Andrew B
authors.initials: AB
authors.lastname: Reeves
authors.affiliation: Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Webby
authors.affiliation: Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Stallknecht
authors.affiliation: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, USA aramey@usgs.gov wan@cvm.msstate.edu.
authors.forename: Xiu-Feng
authors.initials: XF
authors.lastname: Wan
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000821:virology; D001483:Base Sequence; D004196:Disease Outbreaks / Q000662:veterinary*; D004372:Ducks / Q000821:virology*; D019143:Evolution, Molecular; D016679:Genome, Viral / Q000235:genetics*; D009980:Influenza A virus / Q000235:genetics / Q000472:pathogenicity; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology; D010802:Phylogeny; D011201:Poultry Diseases / Q000821:virology; D011995:Recombination, Genetic / Q000235:genetics; D017423:Sequence Analysis, RNA; D014422:Turkeys / Q000821:virology*
keywords: diving duck; evolutionary network; genetic reassortment; highly pathogenic avian influenza; low-pathogenic avian influenza; subtype H7N8; wild birds