title: Interferon-γ influences immunity elicited by vaccines against very virulent Marek's disease virus.
abstract: Vaccination of chickens with herpesvirus of turkey (HVT) confers only partial protection against challenge with a very virulent Marek's disease virus (MDV). Here, we evaluated the ability of recombinant chicken interferon-gamma (rChIFN-γ) to enhance protective efficacy of HVT against the very virulent MDV strain, RB1B. The bioactivity of IFN-γ expressed by a plasmid expression vector was confirmed by its ability to stimulate a chicken macrophage cell line (HD11) to produce nitric oxide (NO) in vitro. The administration of HVT with 5μg of pcDNA:chIFN-γ plasmid reduced the incidence of tumor development significantly when compared to vaccinated birds (77.7% in the HVT+empty vector group and 80% in HVT group versus 33.3% in the HVT+chIFN-γ group) and significantly increased IFN-γ expression in the splenocytes of the protected group, suggesting that rChIFN-γ increases the potency of HVT against MDV. Further analysis demonstrated that the protected birds that received HVT vaccine and/or plasmid had lower MDV genome load and lower amounts of transcripts for meq and vIL-8 than in the birds without lesions. Similarly, lower expression of IL-10, IL-18 and IL-6 was observed in the chickens without lesions compared to the chickens that had lesions, suggesting an inverse association between up-regulation of these cytokines and vaccine-induced immunity. In conclusion, IFN-γ can positively influence immunity conferred by HVT vaccination against challenge with a very virulent Marek's disease virus (vvMDV) in chickens.
authors.affiliation: Department of Pathobiology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors.forename: Kamran
authors.initials: K
authors.lastname: Haq
authors.forename: Inas
authors.initials: I
authors.lastname: Elawadli
authors.forename: Payvand
authors.initials: P
authors.lastname: Parvizi
authors.forename: Amirul I
authors.initials: AI
authors.lastname: Mallick
authors.forename: Shahriar
authors.initials: S
authors.lastname: Behboudi
authors.forename: Shayan
authors.initials: S
authors.lastname: Sharif
mesh_terms: D000818:Animals; D002460:Cell Line; D002645:Chickens; D026002:Herpesvirus 1, Meleagrid / Q000235:genetics / Q000276:immunology*; D008381:Herpesvirus 2, Gallid / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology*; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology; D008380:Marek Disease / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D014611:Vaccination; D014765:Viral Vaccines / Q000008:administration & dosage / Q000235:genetics / Q000276:immunology*; D014774:Virulence
chemical_list: D015850:Interleukin-6; D014765:Viral Vaccines; D016753:Interleukin-10; D007371:Interferon-gamma