Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373 - CCS, Ilha do Fundão, Rio de Janeiro 21941-590, RJ, Brazil.
Int J Antimicrob Agents. 2011 Nov;38(5):435-41. doi: 10.1016/j.ijantimicag.2011.07.002. Epub 2011 Aug 12.
In the present work, the antiviral activity of brequinar (BQR) against the replication of Cantagalo virus was evaluated. BQR is a potent inhibitor of cellular dihydroorotate dehydrogenase, an enzyme of the de novo pyrimidine biosynthetic pathway. Infection in the presence of 0.5μM BQR reduced virus progeny production by >90%, revealing an EC(50) (drug concentration required to inhibit 50% of virus replication) of 0.017μM. Replication of other orthopoxviruses was also inhibited by BQR at similar levels. In the presence of the drug, virus early proteins accumulated to control levels, whereas late gene expression was severely impaired. This result was confirmed by indirect immunofluorescence assays and analysis of time-regulated expression of a reporter gene under the control of a virus promoter. Both assays revealed nearly 90% inhibition of late gene expression. BQR also blocked virus DNA replication, which accounted for the subsequent inhibition of virus late gene expression. The ablation of virus DNA replication, late gene expression and infectious progeny production was restored to control levels when infected cells were co-treated with uridine (URD) and BQR. These data demonstrated that BQR targeted virus DNA synthesis by depleting the cellular pyrimidine pool, which was bypassed by the salvage pathway when URD was added to the cell cultures.
在本工作中，评估了布雷奎纳（BQR）对 Cantagalo 病毒复制的抗病毒活性。BQR 是细胞二氢乳清酸脱氢酶的强效抑制剂，二氢乳清酸脱氢酶是从头嘧啶生物合成途径中的一种酶。在 0.5μM BQR 的存在下感染会使病毒后代的产生减少>90%，显示出 EC50（抑制 50%病毒复制所需的药物浓度）为 0.017μM。BQR 还以类似的水平抑制其他正痘病毒的复制。在药物存在的情况下，病毒早期蛋白积累到对照水平，而晚期基因表达则严重受损。间接免疫荧光测定和在病毒启动子控制下报告基因的时间调节表达分析证实了这一结果。这两种测定都显示晚期基因表达几乎被抑制了 90%。BQR 还阻断了病毒 DNA 的复制，这导致随后对病毒晚期基因表达的抑制。当感染细胞用尿苷（URD）和 BQR 共同处理时，病毒 DNA 复制、晚期基因表达和感染性后代的产生被消除到对照水平。这些数据表明，BQR 通过耗尽细胞嘧啶池来靶向病毒 DNA 合成，当 URD 被添加到细胞培养物中时，该途径可绕过嘧啶池。
