title: Limited Antigenic Diversity in Contemporary H7 Avian-Origin Influenza A Viruses from North America.
abstract: Subtype H7 avian-origin influenza A viruses (AIVs) have caused at least 500 confirmed human infections since 2003 and culling of >75 million birds in recent years. Here we antigenically and genetically characterized 93 AIV isolates from North America (85 from migratory waterfowl [1976-2010], 7 from domestic poultry [1971-2012], and 1 from a seal [1980]). The hemagglutinin gene of these H7 viruses are separated from those from Eurasia. Gradual accumulation of nucleotide and amino acid substitutions was observed in the hemagglutinin of H7 AIVs from waterfowl and domestic poultry. Genotype characterization suggested that H7 AIVs in wild birds form diverse and transient internal gene constellations. Serologic analyses showed that the 93 isolates cross-reacted with each other to different extents. Antigenic cartography showed that the average antigenic distance among them was 1.14 units (standard deviation [SD], 0.57 unit) and that antigenic diversity among the H7 isolates we tested was limited. Our results suggest that the continuous genetic evolution has not led to significant antigenic diversity for H7 AIVs from North America. These findings add to our understanding of the natural history of IAVs and will inform public health decision-making regarding the threat these viruses pose to humans and poultry.
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, the United States.
authors: Yifei
authors: Y
authors: Xu
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, the United States.
authors: Elizabeth
authors: E
authors: Bailey
authors: Exotic and Emerging Avian Viral Diseases Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, US Department of Agriculture, Agricultural Research Service, Athens, Georgia, the United States.
authors: Erica
authors: E
authors: Spackman
authors: Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, the United States.
authors: Tao
authors: T
authors: Li
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, the United States.
authors: Hui
authors: H
authors: Wang
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, the United States.
authors: Li-Ping
authors: LP
authors: Long
authors: National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service, US Department of Agriculture, Fort Collins, Colorado, the United States.
authors: John A
authors: JA
authors: Baroch
authors: Mississippi Field Station, National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service, US Department of Agriculture, Mississippi State, Mississippi, the United States.
authors: Fred L
authors: FL
authors: Cunningham
authors: Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, the United States.
authors: Xiaoxu
authors: X
authors: Lin
authors: Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland, the United States.
authors: Richard G
authors: RG
authors: Jarman
authors: National Wildlife Research Center, Wildlife Services, Animal and Plant Health Inspection Service, US Department of Agriculture, Fort Collins, Colorado, the United States.
authors: Thomas J
authors: TJ
authors: DeLiberto
authors: Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi, the United States.
authors: Xiu-Feng
authors: XF
authors: Wan
mesh_terms: D000818:Animals; D000940:Antigenic Variation / Q000235:genetics / Q000276:immunology; D000956:Antigens, Viral / Q000235:genetics / Q000276:immunology; D002642:Chick Embryo; D002645:Chickens; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics / Q000276:immunology; D006801:Humans; D057920:Influenza A Virus, H7N3 Subtype / Q000235:genetics / Q000276:immunology; D005585:Influenza in Birds / Q000453:epidemiology / Q000235:genetics / Q000276:immunology; D009656:North America
chemical_list: D000956:Antigens, Viral; D019267:Hemagglutinin Glycoproteins, Influenza Virus