Sager H, Brunschwiler C, Jungi T W
Institute of Veterinary Virology, University of Berne, Switzerland.
Parasite Immunol. 1998 Apr;20(4):175-82. doi: 10.1046/j.1365-3024.1998.00141.x.
Theileria are tick-transmitted protozoans causing often fatal diseases in ruminants. Theileria sporozoites immortalize and transform host cells of haematopoietic origin. Transformation is associated with profound functional alterations. For example, bovine cells infected by Theileria annulata or T. parva. constitutively produce interferon (IFN). In this study, the type and family of IFN produced by a panel of T. annulata-transformed cell lines and a T. parva-transformed cell line was investigated, using molecular probes specific for the members of the IFN-alpha, IFN-beta, IFN-gamma and IFN-omega family. T. parva-transformed cells produced IFN-gamma exclusively, whereas T. annulata-infected cells expressed type I IFN only. Analysis of mRNA expression showed that this type I IFN was confined to IFN-beta, regardless of the cellular origin of the transformed cells. When cells were exposed to double-stranded RNA (poly (I:C)) which induces IFN production in other systems, a 10-5,000 fold increase in IFN activity was noted. The amounts of IFN-beta mRNA were increased, but mRNA coding for IFN-alpha, IFN-omega or IFN-gamma was not detected. In contrast, primary macrophages, from which many of the tested lines were derived, expressed IFN-alpha, IFN-beta and IFN-omega mRNA to similar degrees when stimulated by LPS or poly (I:C). Thus, T. annulata appears to constitutively turn on IFN-beta gene transcription while silencing the genes coding for IFN-alpha and IFN-omega.
泰勒虫是通过蜱传播的原生动物，常引起反刍动物的致命疾病。泰勒虫子孢子可使造血起源的宿主细胞永生化并发生转化。这种转化与深刻的功能改变有关。例如，被环形泰勒虫或小泰勒虫感染的牛细胞会持续产生干扰素（IFN）。在本研究中，使用针对IFN-α、IFN-β、IFN-γ和IFN-ω家族成员的分子探针，对一组环形泰勒虫转化细胞系和一个小泰勒虫转化细胞系产生的IFN类型和家族进行了研究。小泰勒虫转化细胞仅产生IFN-γ，而环形泰勒虫感染的细胞仅表达I型IFN。mRNA表达分析表明，无论转化细胞的细胞来源如何，这种I型IFN都局限于IFN-β。当细胞暴露于双链RNA（聚肌胞苷酸）时，在其他系统中会诱导IFN产生，此时可观察到IFN活性增加10至5000倍。IFN-β mRNA的量增加，但未检测到编码IFN-α、IFN-ω或IFN-γ的mRNA。相比之下，许多测试细胞系所源自的原代巨噬细胞在受到脂多糖或聚肌胞苷酸刺激时，会以相似程度表达IFN-α、IFN-β和IFN-ω mRNA。因此，环形泰勒虫似乎会持续开启IFN-β基因转录，同时使编码IFN-α和IFN-ω的基因沉默。
