Pathogenesis of Marek's disease (MD) and possible mechanisms of immunity induced by MD vaccine.
Marek's disease (MD) is a lymphoproliferative disease of chicken, which is characterized by malignant T cell-lymphoma formation. This disease can be effectively prevented by vaccination with attenuated MD virus (MDV), apathogenic MDV or herpesvirus of turkey. MD vaccines are ones of a few vaccines which can prevent virus-induced tumor among mammalian and avian species. To determine the roles of T cell subsets in the protection mechanism, chickens vaccinated with an attenuated MDV (CVI988) were depleted of either CD4+ or CD8+ T cells by neonatal thymectomy and injections of monoclonal antibodies against chicken CD4 or CD8 molecules and then challenged with an oncogenic MDV. These birds were effectively protected from MDV-induced tumors. However, virus titers in CD4+ T cells, which are the main target cells for MDV-latent infection and subsequent transformation, were much higher in CD8-deficient vaccinated chickens than in untreated vaccinated chickens at the early stage of the latent phase. These results suggested that CD8+ T cell responses induced by the MD vaccine are essential for anti-virus but not anti-tumor effects. Here, we will discuss how the attenuated vaccine prevents chickens from lymphoma-formation by an oncogenic MDV.
Morimura
T
T
Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Ohashi
K
K
Sugimoto
C
C
Onuma
M
M
D000818:Animals; D002417:Cattle; D002645:Chickens; D006736:Horses; D016399:Lymphoma, T-Cell / Q000276:immunology / Q000662:veterinary / Q000821:virology; D008380:Marek Disease / Q000276:immunology* / Q000503:physiopathology* / Q000517:prevention & control; D051379:Mice; D011201:Poultry Diseases; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013934:Thymectomy; D014765:Viral Vaccines
D014765:Viral Vaccines