title: IFN-gamma upregulation and protection by macrophage-adapted infectious bursal disease virus.
abstract: Infectious bursal disease virus (IBDV) causes an acute, highly contagious and immunosuppressive disease in chickens. The virus infects and destroys actively dividing IgM-bearing B cells in the bursa. Although antibody response is considered important in defense against virulent IBDV, antibody alone is not sufficient and cell-mediated immunity (CMI) appears to play a critical role. We serially passaged classical IBDV (cIBDV) in MQ-NCSU, an avian macrophage cell line. The macrophage-adapted virus (mcIBDV) was used in ovo to immunize chickens. mcIBDV, which was non-pathogenic and highly protective, induced anti-IBDV antibody and, most importantly, upregulated the expression of IFN-gamma mRNA in spleen. The IFN-gamma upregulation by mcIBDV was significantly higher (P<0.05) than that induced by a commercially available vaccine originated from adaptation of cIBDV in the tissue culture (chicken embryo fibroblast (CEF) cells) (tcIBDV). The level of IFN-gamma upregulation by cIBDV that had been adapted by serial passages to CEF (fcIBDV) was similar to that by tcIBDV and significantly lower (P<0.05) than that by mcIBDV. Virus load was significantly higher (P<0.05) in spleen macrophages obtained from mcIBDV-inoculated chickens than that from fcIBDV-inoculated chickens. These data indicated that adaptation of IBDV to macrophages enhanced the ability of the virus to induce cell-mediated immune response in chickens.
authors.affiliation: Department of Veterinary and Biomedical Sciences, College of Veterinary Medicine, University of Minnesota, 1971 Commonwealth Avenue, St. Paul, MN 55108, USA.
authors.forename: Mahesh
authors.initials: M
authors.lastname: Khatri
authors.forename: Jagdev M
authors.initials: JM
authors.lastname: Sharma
mesh_terms: D000220:Adaptation, Biological; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002460:Cell Line; D049109:Cell Proliferation; D002645:Chickens; D007243:Infectious bursal disease virus / Q000276:immunology*; D007371:Interferon-gamma / Q000096:biosynthesis*; D008214:Lymphocytes / Q000276:immunology; D008264:Macrophages / Q000821:virology*; D012692:Serial Passage; D013154:Spleen / Q000276:immunology / Q000821:virology; D015854:Up-Regulation; D014613:Vaccines, Attenuated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines; D007371:Interferon-gamma