title: Transcriptional analysis of the innate immune response of ducks to different species-of-origin low pathogenic H7 avian influenza viruses.
abstract: BACKGROUND
  Wild waterfowl, including ducks, represent the classic reservoir for low pathogenicity avian influenza (LPAI) viruses and play a major role in the worldwide dissemination of AIV. AIVs belonging to the hemagglutinin (H) 7 subtype are of epidemiological and economic importance due to their potential to mutate into a highly pathogenic form of the virus. Thus far, however, relatively little work has been conducted on elucidating the host-pathogen interactions of ducks and H7 LPAIVs. In the current study, three H7 LPAIVs isolated from either chicken, duck, or turkey avian species were evaluated for their comparative effect on the transcriptional innate immune response of ducks.
  
  
  RESULTS
  Three H7 LPAIV isolates, chicken-origin (A/chicken/Maryland/MinhMa/2004), duck-origin (A/pintail/Minnesota/423/1999), and turkey-origin (A/turkey/Virginia/SEP-67/2002) were used to infect Pekin ducks. At 3 days post-infection, RNA from spleen tissue was used for transcriptional analysis using the Avian Innate Immune Microarray (AIIM) and quantitative real-time RT-PCR (qRT-PCR). Microarray analysis revealed that a core set of 61 genes was differentially regulated in response to all three LPAIVs. Furthermore, we observed 101, 135, and 628 differentially expressed genes unique to infection with the chicken-, duck-, or turkey-origin LPAIV isolates, respectively. qRT-PCR results revealed significant (p<0.05) induction of IL-1β, IL-2, and IFNγ transcription, with the greatest induction observed upon infection with the chicken-origin isolate. Several key innate immune pathways were activated in response to LPAIV infection including the toll-like receptor and RIG-I-like receptor pathways.
  
  
  CONCLUSIONS
  Pekin ducks elicit a unique innate immune response to different species-of-origin H7 LPAIV isolates. However, twelve identifiable genes and their associated cell signaling pathways (RIG-I, NOD, TLR) are differentially expressed regardless of isolate origin. This core set of genes are critical to the duck immune response to AI. These data provide insight into the potential mechanisms employed by ducks to tolerate AI viral infection.
authors.affiliation: Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716, USA.
authors.forename: Michele N
authors.initials: MN
authors.lastname: Maughan
authors.forename: Lorna S
authors.initials: LS
authors.lastname: Dougherty
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Preskenis
authors.forename: Brian S
authors.initials: BS
authors.lastname: Ladman
authors.forename: Jack
authors.initials: J
authors.lastname: Gelb
authors.forename: Erica V
authors.initials: EV
authors.lastname: Spackman
authors.forename: Calvin L
authors.initials: CL
authors.lastname: Keeler
mesh_terms: D000818:Animals; D002645:Chickens; D004372:Ducks; D020869:Gene Expression Profiling; D007113:Immunity, Innate; D009980:Influenza A virus / Q000276:immunology* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000821:virology*; D046228:Microarray Analysis; D060888:Real-Time Polymerase Chain Reaction; D014422:Turkeys