title: The role of T cells in protection by an inactivated infectious bursal disease virus vaccine.
abstract: The current belief is that the humoral immune response plays the principal role in defense against virulent infectious bursal disease virus (IBDV). In this study we used a model, in which chickens were compromised in functional T cells by neonatal thymectomy and Cyclosporin A (TxCsA) treatment, to demonstrate the role of T cells in protective immunity against IBDV. We demonstrated that T cells were necessary to achieve full protection against virulent IBDV. When T cell compromised TxCsA-treated chickens were vaccinated with an inactivated IBDV (iIBDV) vaccine, 91% were not protected against IBDV challenge in comparison to T cell-intact chickens, which had a protection rate of 91%. The iIBDV vaccine induced virus neutralizing (VN) and ELISA antibodies, respectively, in 65 and 5% of TxCsA-treated, and in 100 and 58% of T cell-intact birds. These observations provide evidence that the stimulation of T helper cells is needed for the production of protective antibody levels in iIBDV-vaccinated chickens. Passive administration of VN anti-IBDV antibodies inducing a circulating antibody level of log(2)8 in chickens revealed that the levels of antibodies that protected T cell-intact chickens against virulent IBDV challenge were not protective for TxCsA chickens. These results indicated that antibody alone was not adequate in inducing protection against IBDV in chickens and that T cell-involvement was critical for protection. We propose that the inability of iIBDV to protect TxCsA chickens was due to compromised T cell immunity, functional T helper cells and most likely also cytotoxic T cells are needed in iIBDV vaccine protection.
authors.affiliation: Department of Veterinary PathoBiology, College of Veterinary Medicine, University of Minnesota, St Paul, MN 55108, USA. silke.rautenschlien@tiho-hannover.de
authors.forename: Silke
authors.initials: S
authors.lastname: Rautenschlein
authors.forename: H-Y
authors.initials: HY
authors.lastname: Yeh
authors.forename: J M
authors.initials: JM
authors.lastname: Sharma
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D018175:Birnaviridae Infections / Q000276:immunology* / Q000517:prevention & control* / Q000662:veterinary; D002645:Chickens / Q000276:immunology* / Q000821:virology*; D003520:Cyclophosphamide / Q000276:immunology / Q000494:pharmacology; D016572:Cyclosporine / Q000276:immunology / Q000494:pharmacology; D007166:Immunosuppressive Agents / Q000276:immunology / Q000494:pharmacology; D007243:Infectious bursal disease virus / Q000276:immunology*; D011201:Poultry Diseases / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D013047:Specific Pathogen-Free Organisms; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D013934:Thymectomy; D013950:Thymus Gland / Q000276:immunology; D015164:Vaccines, Inactivated / Q000276:immunology; D014765:Viral Vaccines / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral; D007166:Immunosuppressive Agents; D015164:Vaccines, Inactivated; D014765:Viral Vaccines; D016572:Cyclosporine; D003520:Cyclophosphamide