title: Age is not a determinant factor in susceptibility of broilers to H5N2 clade 2.3.4.4 high pathogenicity avian influenza virus.
abstract: In 2014-2015, the US experienced an unprecedented outbreak of H5 clade 2.3.4.4 highly pathogenic avian influenza (HPAI) virus. The H5N2 HPAI virus outbreak in the Midwest in 2015 affected commercial turkey and layer farms, but not broiler farms. To assess any potential genetic resistance of broilers and/or age-related effects, we investigated the pathogenesis and transmission of A/turkey/Minnesota/12582/2015 (H5N2) (Tk/MN/15) virus in commercial 5-week-old broilers, 8-week-old broilers, and >30-week-old broiler breeders. The mean bird lethal dose (BLD50) was 5.0 log10mean egg infectious dose (EID50) for all age groups. The mean death time (MDT) was statistically not different among the three age groups, ranging between 3.2 and 4.8 days. All broilers that became infected shed high levels of virus with transmission to contacts and demonstrated severe pathology. Mortality and virus shedding results indicated that age is not a determinant factor in susceptibility of broilers to H5N2 clade 2.3.4.4 HPAI virus. Previously, the Tk/MN/15 virus had a BLD50of 3.6 log10EID50and MDT of 2 days in White Leghorn chickens and a BLD50of 5.0 log10EID50and MDT of 5.9 days in turkeys, suggesting that the broiler breed is less susceptible to Midwestern H5N2 virus than the layer breed but similarly susceptible to turkeys. Therefore, genetic resistance of broilers to infection may have accounted only partially for the lack of affected broiler farms in the Midwestern outbreaks, with other contributing factors such as fewer outside to on farm exposure to contacts, type of production management system or enhanced biosecurity.
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA.
authors.forename: Kateri
authors.initials: K
authors.lastname: Bertran
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA.
authors.forename: Dong-Hun
authors.initials: DH
authors.lastname: Lee
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA.
authors.forename: Charles
authors.initials: C
authors.lastname: Balzli
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA.
authors.forename: Mary J
authors.initials: MJ
authors.lastname: Pantin-Jackwood
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA.
authors.forename: Erica
authors.initials: E
authors.lastname: Spackman
authors.affiliation: Exotic and Emerging Avian Viral Diseases Research Unit, Southeast Poultry Research Laboratory, US National Poultry Research Center, Agricultural Research Service, US Department of Agriculture, 934 College Station Rd, Athens, GA, 30605, USA. david.swayne@ars.usda.gov.
authors.forename: David E
authors.initials: DE
authors.lastname: Swayne
mesh_terms: D000367:Age Factors; D000818:Animals; D002645:Chickens / Q000276:immunology / Q000821:virology; D004198:Disease Susceptibility / Q000276:immunology / Q000662:veterinary*; D053125:Influenza A Virus, H5N2 Subtype / Q000235:genetics / Q000276:immunology / Q000472:pathogenicity; D005585:Influenza in Birds / Q000276:immunology / Q000473:pathology / Q000821:virology*; D008246:Lysophospholipids; D011201:Poultry Diseases / Q000276:immunology / Q000473:pathology / Q000821:virology*; D017201:Virus Shedding
chemical_list: C099529:1-O-(9',10'-methanohexadecanoyl)-sn-glycero-2,3-cyclic phosphate; D008246:Lysophospholipids