title: An ex vivo swine tracheal organ culture for the study of influenza infection.
abstract: BACKGROUND
  The threat posed by swine influenza viruses with potential to transmit from pig populations to other hosts, including humans, requires the development of new experimental systems to study different aspects of influenza infection. Ex vivo organ culture (EVOC) systems have been successfully used in the study of both human and animal respiratory pathogens.
  
  
  OBJECTIVE
  We aimed to develop an air interface EVOC using pig tracheas in the study of influenza infection demonstrating that tracheal explants can be effectively maintained in organ culture and support productive influenza infection.
  
  
  METHODS
  Tracheal explants were maintained in the air interface EVOC system for 7 days. Histological characteristics were analysed with different staining protocols and co-ordinated ciliary movement on the epithelial surface was evaluated through a bead clearance assay. Explants were infected with a swine H1N1 influenza virus. Influenza infection of epithelial cells was confirmed by immunohistochemistry and viral replication was quantified by plaque assays and real-time RT-PCR.
  
  
  RESULTS
  Histological analysis and bead clearance assay showed that the tissue architecture of the explants was maintained for up to 7 days, while ciliary movement exhibited a gradual decrease after 4 days. Challenge with swine H1N1 influenza virus showed that the EVOC tracheal system shows histological changes consistent with in vivo influenza infection and supported productive viral replication over multiple cycles of infection.
  
  
  CONCLUSIONS
  The air interface EVOC system using pig trachea described here constitutes a useful biological tool with a wide range of applications in the study of influenza infection.
authors.affiliation: Department of Veterinary Medicine, University of Cambridge, Cambridge, UK.
authors.forename: Sandro F
authors.initials: SF
authors.lastname: Nunes
authors.forename: Pablo R
authors.initials: PR
authors.lastname: Murcia
authors.forename: Laurence S
authors.initials: LS
authors.lastname: Tiley
authors.forename: Ian H
authors.initials: IH
authors.lastname: Brown
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Tucker
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Maskell
authors.forename: James Lionel N
authors.initials: JL
authors.lastname: Wood
mesh_terms: D000818:Animals; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000254:growth & development*; D007251:Influenza, Human / Q000821:virology*; D009924:Organ Culture Techniques; D009976:Orthomyxoviridae Infections / Q000821:virology*; D020545:Respiratory Mucosa / Q000821:virology; D013552:Swine; D014132:Trachea / Q000821:virology*; D014776:Virus Cultivation / Q000379:methods*