用瞬时表达分析等方法，证明牛泡沫病毒（ＢＳＶ）３０２６中国毒株能在体外激活牛免疫缺陷病毒（ＢＩＶ）基因表达，ＢＳＶ３０２６编码的反式激活因子Ｂｏｒｆ１行使这种激活作用。缺失突变分析表明，Ｂｏｒｆ１在ＢＩＶＬＴＲ上靶序列位于－４１０／－１１５（＋１为转录起始位点）区域，但其中的ＮＦＢ位点（－３６７／－３１９）与这种激活作用无关，包括转录起点下游（ＲＵ５区）在内的－１１５／＋２０４区域也与这种激活作用无关。该结果对研究ＢＩＶ致病机理及防治ＡＩＤＳ有重要意义。

Bovine spumavirus (BSV) 3026 China strain, which was isolated by authors, encodes the transcriptional transactivator Borf 1. The Borf 1 protein, as well as the BSV3026, can transactivate the gene expression directed by bovine immunodeficiency virus long terminal repeat (BIV LTR) in transient transfection assays. To identify the specific region in BIV LTR responsible for the Borf 1 action, it was examined that the effect of the Borf 1 on firefly luciferase (Luc) gene expression in transfected cells with a series of mutant pBIV LTR luc plasmids. The region between -410 and -115 from the transcription initiation site was identified as responsible for the transactivation by the Borf 1. However, the regions between -367 and -319 (NF B site), between -52 and +204, which are very important in the activation of BIV transcription, are dispensable for the Borf 1 mediated transactivation.