Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Miaoli 350, Taiwan.
Antimicrob Agents Chemother. 2012 Feb;56(2):647-57. doi: 10.1128/AAC.00125-11. Epub 2011 Sep 19.
The aim of this study was to identify the antiviral mechanism of a novel compound, BPR3P0128. From a large-scale screening of a library of small compounds, BPR3P compounds were found to be potent inhibitors of influenza viral replication in Madin-Darby canine kidney (MDCK) cells. BPR3P0128 exhibited inhibitory activity against both influenza A and B viruses. The 50% inhibitory concentrations were in the range of 51 to 190 nM in MDCK cells, as measured by inhibition-of-cytopathic-effect assays. BPR3P0128 appeared to target the viral replication cycle but had no effect on viral adsorption. The inhibition of cap-dependent mRNA transcription by BPR3P0128 was more prominent with a concurrent increase in cap-independent cRNA replication in a primer extension assay, suggesting a role of BPR3P0128 in switching transcription to replication. This reduction in mRNA expression resulted from the BPR3P-mediated inhibition of the cap-dependent endoribonuclease (cap-snatching) activities of nuclear extracts containing the influenza virus polymerase complex. No inhibition of binding of 5' viral RNA to the viral polymerase complex by this compound was detected. BPR3P0128 also effectively inhibited other RNA viruses, such as enterovirus 71 and human rhinovirus, but not DNA viruses, suggesting that BPR3P0128 targets a cellular factor(s) associated with viral PB2 cap-snatching activity. The identification of this factor(s) could help redefine the regulation of viral transcription and replication and thereby provide a potential target for antiviral chemotherapeutics.
本研究旨在确定新型化合物 BPR3P0128 的抗病毒机制。从大规模筛选小分子化合物文库中，发现 BPR3P 化合物可有效抑制犬肾细胞（MDCK）中的流感病毒复制。BPR3P0128 对甲型和乙型流感病毒均具有抑制活性。在 MDCK 细胞中，通过细胞病变抑制试验测定，50%抑制浓度（IC50）范围为 51 至 190 nM。BPR3P0128 似乎靶向病毒复制周期，但对病毒吸附没有影响。BPR3P0128 抑制帽依赖性 mRNA 转录的作用更为明显，同时在引物延伸试验中，帽非依赖性 cRNA 复制增加，表明 BPR3P0128 在转录向复制转换中起作用。这种 mRNA 表达的减少是由于 BPR3P 介导的核提取物中流感病毒聚合酶复合物的帽依赖性内切酶（帽抢夺）活性抑制所致。该化合物未检测到抑制 5'病毒 RNA 与病毒聚合酶复合物的结合。BPR3P0128 还能有效抑制其他 RNA 病毒，如肠道病毒 71 和人鼻病毒，但不能抑制 DNA 病毒，这表明 BPR3P0128 靶向与病毒 PB2 帽抢夺活性相关的细胞因子（s）。鉴定这种因子（s）可以帮助重新定义病毒转录和复制的调控，并为抗病毒化学疗法提供潜在的靶点。
