牛泡沫病毒内部启动子的克隆及功能分析

Cloning and Functional Analysis of the Internal Promoter of a Bovine Foamy Virus

以该实验室分离并鉴定的牛泡沫病毒 (BFV)中国毒株 (BFV3 0 2 6)为材料 ,用PCR方法首次克隆了位于 env 基因 3′端的内部启动子 ,经序列分析后 ,引入luc基因作瞬时表达分析。结果表明 ,该内部启动子不但基础活性高于LTR ,而且转录活性在Tas参与下被大大激活 ,其激活活性也远远高于LTR。同源分析表明 ,非灵长类泡沫病毒内部启动子之间的同源性高于其与灵长类泡沫病毒内部启动子之间的同源性。

Bovine foamy virus is a member of spumavirus that encodes three retroviral genes, gag, pol and env for virion proteins as well as additional open reading frames. ORF-1 was proven to be a viral transactivator which augmented transcription directed by the long terminal repeat (LTR) through cis-acting targets in the U3 domain of the LTR. Recently, we demonstrated by using sequence analysis and transient expression assay that a newly isolated BFV 3026 strain also encoded an internal promoter (IP) in the 3' end of BFV env gene. Transcription directed by the IP of BFV was greatly activated by the ORF-1 in BL-12 cell line. Furthermore, both the basal activity and enhanced activity of IP were much greater than those of LTR, which suggests that different transactivation mechanisms were involved in regulating BFV LTR and IP.