文摘
The avian Metapneumovirus (aMPV) causes an economically important acute respiratory disease in turkeys (turkey rhinotracheitis, TRT). While antibodies were shown to be insufficient for protection against aMPV-infection, the role of T-lymphocytes in the control of aMPV-infection is not clear. In this study we investigated the role of T-lymphocytes in aMPV-pathogenesis in a T-cell-suppression model in turkeys. T-cell-intact turkeys and turkeys partly depleted of functional CD4<sup>+sup> and CD8<sup>+sup> T-lymphocytes by Cyclosporin A (CsA) treatment were inoculated with the virulent aMPV subtype A strain BUT 8544. CsA-treatment resulted in a significant reduction of absolute numbers of circulating CD4<sup>+sup> and CD8α<sup>+sup> T-lymphocytes by up to 82 and 65 % , respectively (P < 0.05). Proportions of proliferating T-cells within mitogen-stimulated peripheral blood mononuclear cells were reduced by similar levels in CsA-treated birds compared to untreated controls (P < 0.05). CsA-treated turkeys showed delayed recovery from aMPV-induced clinical signs and histopathological lesions and a prolonged detection of aMPV in choanal swabs. The results of this study show that T-lymphocytes play an important role in the control of primary aMPV-infection in turkeys.