DNA TOPOMERASE 1 ACTIVITY IN RETROVIRUSES

拓扑异构酶是修饰DNA拓扑状态的酶， 已被证明参与DNA复制和转录。 由于逆转录病毒的复制、整合和表达过程 可能需要在集成或 未整合的前病毒，我们已经开始确定拓扑异构酶是否发挥作用， 在逆转录病毒生长或感染中起关键作用，或者如果拓扑异构酶 可能是控制逆转录病毒感染的目标。 我们以前描述了一种新的拓扑异构酶I（topo I）活性 与各种逆转录病毒和慢病毒颗粒相关，并显示 特异性拓扑异构酶I抑制剂喜树碱（CPT）可以阻断HIV 感染组织培养中的H9细胞。 用脾成焦 作为一个体内模型，我们已经证明了SFFV诱导脾肿大的作用 CPT与病毒共注射时可以阻断SFFV诱导的疾病 植入易感小鼠体内 确定CPT影响慢性 病毒生产的感染细胞，我们处理CF2 Th（狗胸腺）细胞 用CPT生产马传染性贫血病毒。 连续暴露 低水平的药物导致85-92%的病毒产生抑制， 如通过释放到培养基中的RT所测量的，以及类似的 通过免疫荧光检测病毒蛋白产生的降低水平， 放射免疫沉淀分析。

Topoisomerases are enzymes which modify the topological state of DNA and have been shown to be involved in DNA replication and transcription. Since the process of retroviral replication, integration and expression are likely to require topological changes in either the integrated or unintegrated provirus, we have begun to determine if topoisomerases play a critical role in retrovirus growth or infection, or if topoisomerases might be a target for the control of retroviral infections. We had previously described a novel topoisomerase I (topo I) activity associated with various retrovirus and lentivirus particles, and showed that the specific topo I inhibitor, camptothecin (CPT), could block HIV infection of H9 cells in tissue culture. Using spleen focus-forming virus (SFFV) induction of splenomegaly as an in vivo model, we have shown that CPT can block SFFV-induced diseases when coinjected with the virus into susceptible mice. To determine the ability of CPT to affect chronic virus production by infected cells, we treated CF2Th (dog thymus) cells producing equine infectious anemia virus with CPT. Continuous exposure to low levels of the drug resulted in 85-92% inhibition of virus produc- tion, as measured by RT released into the culture media, and similar levels of reduction in viral protein production by immunofluorescence and radioimmunoprecipitation analysis.