title: Role of chicken melanoma differentiation-associated gene 5 in induction and activation of innate and adaptive immune responses to infectious bursal disease virus in cultured macrophages.
abstract: The objective of the present study was to determine if chicken melanoma-differentiation-associated gene 5 (MDA5) senses infectious bursal disease virus infection to induce innate immunity that bridges to adaptive immunity. During IBDV infection in HD11 cells, IBDV titers and RNA loads increased up to 3.4 × 10(7) plaque-forming units (PFU)/mL and 1114 ng/µL, respectively, at 24 hours postinfection (hpi). IBDV infection in HD11 cells induced significantly upregulated (p < 0.05) expression levels of chicken MDA5 (59-fold), interferon-β (IFN-β) (693-fold), dsRNA-dependent protein kinase (PKR) (4-fold), 2', 5'-oligoadenylate synthetase (OAS) (286-fold), myxovirus resistance gene (Mx) (22-fold), interleukin-1β (IL-1β) (5-fold), IL-6 (146-fold), IL-8 (4-fold), IL-10 (4-fold), inducible nitric oxide synthase (iNOS) (15-fold), and major histocompatibility complex class I (MHC class I) (4-fold). Nitric oxide production in the culture supernatants increased significantly (p < 0.05) up to 6.5 μM at 24 hpi. The expressed chMDA5 and IBDV-derived dsRNA were localized in the cytoplasm of HD11 cells during IBDV infection. ChMDA5-knockdown HD11 cells had significantly higher (p < 0.05) IBDV RNA loads at 24 hpi and significantly lower (p < 0.05) nitric oxide production and expression levels of chicken MDA5, IFN-β, PKR, OAS, Mx, IL-1β, IL-6, IL-8, IL-12(p40), IL-18, IL-10, iNOS, MHC class I and CD86 at 24 hpi. In addition, chMDA5 overexpression in HD11 cells resulted in significantly reduced (p < 0.05) IBDV titers and RNA loads and significantly increased (p < 0.05) nitric oxide production at 16 and 24 hpi. It also resulted in significantly higher (p < 0.05) expression levels of chicken MDA5, IFN-β, PKR, OAS, Mx, IL-1β, IL-6, IL-8, IL-12(p40), IL-10 and iNOS at 2 hpi. In conclusion, the results indicate that chMDA5 senses IBDV infection in chicken macrophages, and this is associated with IBDV-induced expression of IFN-β and initiation of an innate immune response that in turn activates the adaptive immune response and limits IBDV replication.
authors.affiliation: Department of Comparative Pathobiology, Purdue University, 406, S. University St, West Lafayette, IN, 47907, USA.
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Lee
authors.affiliation: Department of Comparative Pathobiology, Purdue University, 406, S. University St, West Lafayette, IN, 47907, USA.
authors.forename: Ching Ching
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Department of Comparative Pathobiology, Purdue University, 406, S. University St, West Lafayette, IN, 47907, USA. tllin@purdue.edu.
authors.forename: Tsang Long
authors.initials: TL
authors.lastname: Lin
mesh_terms: D056704:Adaptive Immunity; D000818:Animals; D018175:Birnaviridae Infections / Q000235:genetics / Q000276:immunology / Q000662:veterinary* / Q000821:virology; D002645:Chickens; D016207:Cytokines / Q000235:genetics / Q000276:immunology; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000276:immunology*; D007113:Immunity, Innate; D007243:Infectious bursal disease virus / Q000235:genetics / Q000502:physiology*; D008264:Macrophages / Q000201:enzymology / Q000276:immunology* / Q000821:virology; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000276:immunology; D011201:Poultry Diseases / Q000201:enzymology / Q000276:immunology* / Q000821:virology
chemical_list: D016207:Cytokines; D052247:Nitric Oxide Synthase Type II; D053487:DEAD-box RNA Helicases