BFV Borf-1蛋白激活自身及异源（BIV）启动子的机理研究

本研究拟对牛泡沫病毒（BFV）反式激活因子Brof-1在不同启动子上的应答元件（TRE）进行精确定位，确定TREs的共有序列，探讨是否有细胞因子参与共有序列与Brof-1识别过程，并初步确定Brof-1 蛋白激活不同启动子的功能域，揭示BROF-1对自身和异源（BIV）启动子作用的可能机制，也为阐明泡沫病毒在慢病毒致病过程中的作用提供理论依据。

Bovine Foamy Virus (BFV) possesses a complex genome. The Borf-1 protein, encoded by the first open reading frame (orf-1) between env and 3` LTR in the BFV genome, has been characterized as a transcriptional activator (TAS). To define the structural function of Borf-1, a series of plasmids expressing full-length Borf-1 and its deletions were constructed by PCR using as template the Hirt DNA of FBL cells infected with the BFV3026 China Strain. After those proteins were expressed in E. coli and purified by chromatography, their binding and activating functions were detected by the eletrophoretic mobility shift assay and transient expression assay. These data demonstrate that Borf-1 is a sequence-specific DNA binding protein. It can function efficiently transmembrane. The minimal Tas response element (TRE) regions of Borf-1 located in BFV long terminal repeat (LTR), internal promoter (IP) and bovine immunodeficiency virus (BIV) lie between -380 to -140nt (TRE II), 9205 to 9276nt (TREIP) and -410 to -115nt (TRE BIV) , respectively. The functional domain of the Borf-1 protein required for transactivation towards different promoters is different. However, the Borf-1 protein likely binds both viral promoters via a similar pattern. Its binding is necessary for efficient transcriptional activation.