title: The effects of H3N2 swine influenza virus infection on TLRs and RLRs signaling pathways in porcine alveolar macrophages.
abstract: BACKGROUND
  Swine influenza is an economically important respiratory disease of swine resulting from infection with influenza A virus. Swine influenza virus (SIV) becomes the focus as pigs have been hypothesized to serve as an intermediate host for the adaptation of avian influenza viruses to humans or as mixing vessels for the generation of genetically reassortant viruses. The ability of the innate immune system to detect and respond to pathogens is important for survival. Therefore, there is a critical need to evaluate the immediate response to viral infection, especially the role of the toll-like receptors (TLRs) and RNA helicase RIG-I-like receptors (RLRs) innate immunity signaling pathways in H3N2 swine influenza virus infection.
  
  
  METHODS
  In this study, porcine alveolar macrophages (PAMs) were obtained from porcine lungs and were infected with SIV at a multiplicity of infection (MOI) of 5 in vitro. The changes of the related receptors, signaling proteins and effector molecules of TLRs and RLRs signaling pathways post H3N2 virus infection of PAMs were quantified by Real-time quantitative RT-PCR and western blotting.
  
  
  RESULTS
  The results showed that H3N2 SIV infection significantly increased mRNA expression of TLR-3, TLR-7, RIG- I and MDA5 after 4 hpi (P < 0.05). Western blotting showed that the protein levels of TLR-3, TLR-7 and RIG-I also had a significantly increase after PAM exposed to virus. A significant change of MyD88, MAVS, IRF-3 and IRF-7 mRNA expression were present at 8 hpi. More than a 4-fold increase was induced for TNF-α and IL-1β mRNA expression. And the concentration of TNF-α and IL-1β peaked at 12 and 24 hpi, respectively. IFN-α, IFN-β mRNA and protein levels increased after SIV infection and significant differences was observed at 8, 12 and 24 hpi.
  
  
  CONCLUSIONS
  These results indicate that H3N2 swine influenza virus infection significantly influences the expression of the receptors, adapter proteins and downstream effector molecules of RLRs and TLRs signaling pathways. This study enhances our understanding of innate immunity signaling pathways in PAM anti-infection of H3N2 SIV.
authors.affiliation: National Research Center for Veterinary Vaccine Engineering and Technology of China, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China. jqzh03@126.com.|College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. jqzh03@126.com.
authors.forename: Jinqiu
authors.initials: J
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. mjf171647@126.com.
authors.forename: Jinfeng
authors.initials: J
authors.lastname: Miao
authors.affiliation: National Research Center for Veterinary Vaccine Engineering and Technology of China, Jiangsu Academy of Agricultural Sciences, Nanjing, 210014, China. hjb@jaas.ac.cn.
authors.forename: Jibo
authors.initials: J
authors.lastname: Hou
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, 210095, China. lucp@njau.edu.cn.
authors.forename: Chengping
authors.initials: C
authors.lastname: Lu
mesh_terms: D000818:Animals; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D015870:Gene Expression; D053122:Influenza A Virus, H3N2 Subtype / Q000502:physiology*; D016676:Macrophages, Alveolar / Q000276:immunology / Q000821:virology*; D053594:Myeloid Differentiation Factor 88 / Q000235:genetics / Q000378:metabolism; D009976:Orthomyxoviridae Infections / Q000662:veterinary*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013552:Swine; D013553:Swine Diseases / Q000235:genetics / Q000276:immunology / Q000378:metabolism* / Q000821:virology*; D051193:Toll-Like Receptors / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D016207:Cytokines; D053594:Myeloid Differentiation Factor 88; D012333:RNA, Messenger; D051193:Toll-Like Receptors