Detection of Bluetongue Virus in Tissues of Experimentally Infected Sheep
Date Issued
2009
Date
2009
Author(s)
Chen, Jiun-Liang
Abstract
Bluetongue virus (BTV), a member of the Orbivirus genus of the family Reoviridae, is the causative agent of a noncontagious, insect-borne disease. Bluetongue virus infection involves domestic and wild ruminants, and causes thrombo-hemorrhagic fevers mainly in sheep. The BTVs were first isolated from domestic ruminants in Taiwan in year 2003, respectively BTV2-KM-2003 from goats and BTV12-PT-2003 from dairy cattle. So far, there is no clinical outbreak of BTV in Taiwan. n experimental infection of BTV2-KM-2003 had been conducted for evaluating its virulence on Corriedale sheep, one of the predominant breeds in Taiwan, and then euthanatized at 7 and 11 days post-infection (DPI). No obvious clinical signs were noted, except for a mild fever at DPI 4 or 5. Histological lesions were characterized by multifocal hemorrhage with mild to moderate infiltration of mononuclear cells and edema in the contralateral ear pinna, tongue, and facial skin, but the characteristic ecchymotic hemorrhage at the base of pulmonary artery of virulent BTV was absent.he purpose of this study was to detect the BTV in experimentally infected Corriedale sheep by immunohistochemistry (IHC) and in-situ hybridization (ISH) in order to correlate viral distributions with the lesions, and to further the understanding of pathogenesis. Viral antigen signals were detected by IHC in the spleen, lymph node, tonsil, contralateral ear pinna, tongue, and facial skin. The presence of BTV antigen signals in the inflammatory areas correlated with the lesions on sites. While in the spleen, strong BTV signals were chiefly located in macrophages of the marginal zone and T lymphocytes of the red pulp on DPI 7, by DPI 11 most BTV signals shifted to macrophages and small lymphocytes within the general center, presumbably coincident with the antigen capture and stimulation for antibody synthesis. The results of ISH were similar to those of IHC, except that B lymphocytes of the marginal zone were also detected. Based on the clinical signs, gross and histological findings, the Taiwan isolate BTV2-KM-2003 was able to induce mild petechiated hemorrhages and to establish non-lethal infection, and is thus of low virulence to Corriedale sheep.
Subjects
Bluetongue virus
sheep
spleen
Taiwan
Immunohistochemistry
In-situ hybridization
Type
thesis
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