牛病毒性腹泻病毒（BVDV）在全球范围内广泛流行，给世界各国养牛业造成巨大的经济损失。BVDV持续感染是该病毒流行的主要原因，由于大多数感染牛群呈隐性，给根除和控制该病带来很大的挑战。目前BVDV持续感染的机制尚不清楚，最新研究表明，CXCR4基因在持续感染动物中的低表达可能参与调控Ⅰ型干扰素通路抑制机体免疫应答反应。为了证明这一假说，我们拟通过临床持续感染动物模型，应用RT-PCR和流式细胞技术分析持续感染牛CXCR4基因的表达与持续感染免疫耐受的关系，体外应用基因重组技术以及RNAi技术构建CXCR4基因沉默细胞株，从多个水平探究CXCR4参与在BVDV持续感染过程中调节免疫耐受的调控机制，此研究将为BVDV的防治提供新的思路和新靶点。

The spread widely of Bovine viral diarrhea virus(BVDV ) causes continued substantial economic losses in the cattle industry worldwide.In countries with high BVDV prevalence and intensive trade,the aim should be to minimize infection pressure,while the identification and elimination of persistently infected(PI) animals is of utmost importance in any scenario.The mechanism of BVDV persistently infectied is unclear. Long term decrease in CXCR4 concentration in blood of cows with PI fetuses was hypothesized to be mediated by factors released by the PI fetus into maternal circulation.To prove this hypothesis, the project intends to apply real-time PCR, Flow cytometry technology, Western blotting, RNA interference technology in research of IFN-1 signaling pathway in the process of persistently infected, in order to reveal the mechanism of IFN-1 signal pathway in persistently infected development,explore the mechanisms regulating the immune tolerance of CXCR4 from multiple levels. The above studies will provide new ideas and drug targets for prevention and treatment of BVDV.