title: Infection of swine ex vivo tissues with avian viruses including H7N9 and correlation with glycomic analysis.
abstract: OBJECTIVE
  Swine have been regarded as intermediate hosts in the spread of influenza from birds to humans but studies of the sialylated glycans that comprise their respiratory tract have not been extensively studied in the past. This study analyzed the sialylated N-glycan and O-glycan profile of swine trachea and lung and correlated this with ex-vivo infection of swine explants with avian influenza viruses.
  
  
  METHODS
  Lungs and tracheal samples were obtained from normal farm and laboratory raised swine and used for ex vivo infection as well as mass spectrometric analysis. Infection of the ex vivo tissues used high pathogenic and low pathogenic avian viruses including the novel H7N9 virus that emerged in China in early 2013.
  
  
  METHODS
  Assessment of successful replication was determined by TCID50 as well as virus immunohistochemistry. The N-glycan and O-glycan profiles were measured by MALDI-TOF and sialylated linkages were determined by sialidase treatment. Lectin binding histochemistry was also performed on formalin fixed tissue samples with positive binding detected by chromogen staining.
  
  
  RESULTS
  The swine respiratory tract glycans differed from the human respiratory tact glycans in two main areas. There was a greater abundance of Gal-α-Gal linkages resulting in a relative decrease in sialylated glycans. The swine respiratory tract also had a greater proportion of glycans containing Neu5Gc and Siaα2-6 glycans than the human respiratory tract. Infection with avian viruses was confined primarily to lung bronchioles rather than trachea and parenchyma.
  
  
  CONCLUSIONS
  In contrast to previous studies we found that there was not as much expression of Siaα2-3 glycans on the surface of the trachea. Infection of Siaα2-3 binding avian viruses was restricted to the lower respiratory tract bronchioles. This finding may diminish the ability of the swine to act as an intermediary in the transmission of avian viruses to humans.
authors.affiliation: Department of Pathology, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China; Centre of Influenza Research, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, China.
authors.forename: Renee W Y
authors.initials: RW
authors.lastname: Chan
authors.forename: Rositsa
authors.initials: R
authors.lastname: Karamanska
authors.forename: Sjouke
authors.initials: S
authors.lastname: Van Poucke
authors.forename: Kristien
authors.initials: K
authors.lastname: Van Reeth
authors.forename: Icarus W W
authors.initials: IW
authors.lastname: Chan
authors.forename: Michael C W
authors.initials: MC
authors.lastname: Chan
authors.forename: Anne
authors.initials: A
authors.lastname: Dell
authors.forename: Joseph S M
authors.initials: JS
authors.lastname: Peiris
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Haslam
authors.forename: Yi
authors.initials: Y
authors.lastname: Guan
authors.forename: John M
authors.initials: JM
authors.lastname: Nicholls
mesh_terms: D000818:Animals; D001717:Birds; D002681:China; D054794:Glycomics; D006651:Histocytochemistry; D009980:Influenza A virus / Q000254:growth & development* / Q000302:isolation & purification; D005585:Influenza in Birds / Q000635:transmission* / Q000821:virology; D009924:Organ Culture Techniques; D009976:Orthomyxoviridae Infections / Q000635:transmission* / Q000821:virology; D011134:Polysaccharides / Q000032:analysis*; D012137:Respiratory System / Q000737:chemistry* / Q000821:virology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013552:Swine
chemical_list: D011134:Polysaccharides
keywords: Glycomics; influenza A virus; swine