title: Expression of interferon gamma by a highly virulent strain of Newcastle disease virus decreases its pathogenicity in chickens.
abstract: The role of interferon gamma (IFN-γ) expression during Newcastle disease virus (NDV) infection in chickens is unknown. Infection of chickens with highly virulent NDV results in rapid death, which is preceded by increased expression of IFN-γ in target tissues. IFN-γ is a cytokine that has pleiotropic biological effects including intrinsic antiviral activity and immunomodulatory effects that may increase morbidity and mortality during infections. To better understand how IFN-γ contributes to NDV pathogenesis, the coding sequence of the chicken IFN-γ gene was inserted in the genome of the virulent NDV strain ZJ1 (rZJ1-IFNγ), and the effects of high levels of IFN-γ expression during infection were determined in vivo and in vitro. IFN-γ expression did not significantly affect NDV replication in fibroblast or in macrophage cell lines. However, it affected the pathogenesis of rZJ1-IFNγ in vivo. Relative to the virus expressing the green fluorescent protein (rZJ1-GFP) or lacking the IFN-γ insert (rZJ1-rev), expression of IFN-γ by rZJ1-IFNγ produced a marked decrease of pathogenicity in 4-week-old chickens, as evidenced by lack of mortality, decreased disease severity, virus shedding, and antigen distribution. These results suggest that early expression of IFN-γ had a significant protective role against the effects of highly virulent NDV infection in chickens, and further suggests that the level and timing of expression of this cytokine may be critical for the disease outcome. This is the first description of an in vivo attenuation of a highly virulent NDV by avian cytokines, and shows the feasibility to use NDV for cytokine delivery in chicken organs. This approach may facilitate the study of the role of other avian cytokines on the pathogenesis of NDV.
authors.affiliation: Southeast Poultry Research Laboratory USDA ARS, 934 College Station Rd., Athens, GA 30605, USA.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Susta
authors.forename: Ingrid
authors.initials: I
authors.lastname: Cornax
authors.forename: Diego G
authors.initials: DG
authors.lastname: Diel
authors.forename: Stivalis Cardenas
authors.initials: SC
authors.lastname: Garcia
authors.forename: Patti J
authors.initials: PJ
authors.lastname: Miller
authors.forename: Xiufan
authors.initials: X
authors.lastname: Liu
authors.forename: Shunlin
authors.initials: S
authors.lastname: Hu
authors.forename: Corrie C
authors.initials: CC
authors.lastname: Brown
authors.forename: Claudio L
authors.initials: CL
authors.lastname: Afonso
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens / Q000276:immunology / Q000821:virology*; D005347:Fibroblasts / Q000821:virology; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D008264:Macrophages / Q000821:virology; D009521:Newcastle Disease / Q000276:immunology* / Q000401:mortality / Q000473:pathology / Q000821:virology; D009522:Newcastle disease virus / Q000276:immunology / Q000472:pathogenicity*; D014774:Virulence; D014779:Virus Replication
chemical_list: D007371:Interferon-gamma
keywords: Chicken IFN-γ; Cytokine storm; GFP; ICPI; IFN-α; IFN-β; IFN-γ; IL-6; ISRGs; Immunopathogenesis; MALT; ND; NDV; NO; Newcastle disease; Newcastle disease virus; Pathogenesis; Reverse genetics; SAA1; green fluorescent protein; iNOS; inducible nitric oxide synthetase; interferon alpha; interferon beta; interferon gamma; interferon-stimulated response genes; interleukin six; intra cerebral pathogenicity index; mucosa associated lymphoid tissue; nitric oxide; serum amyloid protein A