title: Comparison of the expression of cytokine genes in the bursal tissues of the chickens following challenge with infectious bursal disease viruses of varying virulence.
abstract: BACKGROUND
  Cytokines are important mediators and regulators of host responses against foreign antigen, with their main function to orchestrate the functional activities of the cells of the immune system. However little is known about the role of cytokines in pathogenesis and immune responses caused by infectious bursa disease virus (IBDV). The aim of this study was to examine the transcripts of cell-mediated immune response-related cytokine genes in the bursal tissues of chickens infected with IBDVs of varying virulence to gain an understanding of pathological changes and mechanisms of immunosuppression caused by IBDV infection and the immune responses evoked.
  
  
  RESULTS
  Real-time quantitative PCR analysis revealed that the expression levels of both Th1 [interferon (IFN)-γ, interleukins (IL)-2 and IL-12p40] and Th2 (IL-4, IL-5, IL-13 and IL-10) cytokines were significantly up-regulated following challenge with the H strain (vvIBDV) and up to 2- and 30-fold, respectively (P < 0.05). Following infection with the Ts strain (cell-adapted virus) these cytokine transcripts were up-regulated at 5 days post-infection (dpi), 2- and 13-fold respectively (P < 0.05), while the expression levels of IL-2 and IL-4 were not significantly different (P > 0.05). A higher degree of cytokine expression was induced by the H strain compared with the Ts strain.
  
  
  CONCLUSIONS
  The results indicate that the expression of cell-mediated immune-related cytokine genes is strongly induced by IBDV, especially by the vvIBDV, H strain and reveal that these cytokines could play a crucial role in driving cellular immune responses during the acute phase of IBDV infection, and the cellular immune responses caused by IBDV of varying virulence are through different signaling pathways.
authors.affiliation: State Key Laboratory for Agrobiotechnology, College of Biological Sciences, China Agricultural University, No. 2 Yuan Ming Yuan West Road, Beijing 100193, China.
authors.forename: Haiwen
authors.initials: H
authors.lastname: Liu
authors.forename: Manfu
authors.initials: M
authors.lastname: Zhang
authors.forename: Haitang
authors.initials: H
authors.lastname: Han
authors.forename: Jihong
authors.initials: J
authors.lastname: Yuan
authors.forename: Zandong
authors.initials: Z
authors.lastname: Li
mesh_terms: D000818:Animals; D018175:Birnaviridae Infections / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D002060:Bursa of Fabricius / Q000473:pathology / Q000821:virology; D002645:Chickens; D016207:Cytokines / Q000096:biosynthesis*; D015870:Gene Expression; D020869:Gene Expression Profiling; D007243:Infectious bursal disease virus / Q000276:immunology* / Q000472:pathogenicity*; D011201:Poultry Diseases / Q000276:immunology* / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018417:Th1 Cells / Q000276:immunology; D013997:Time Factors; D014774:Virulence
chemical_list: D016207:Cytokines