人肠道病毒71型(EV71)是手部的主要病原,脚,和儿童的口蹄疫(HFMD)。手足口病流行几十年来一直是亚太地区的公共卫生问题,没有疫苗和有效的抗病毒药物。几个世纪以来,姜黄素一直被用作传统药物来治疗包括病毒感染在内的多种疾病。在这项研究中,我们证明姜黄素再次显示出有效的抗病毒作用EV71.在感染EV71的Vero细胞中,姜黄素的添加显著抑制了病毒RNA的合成,病毒蛋白的表达,以及病毒后代的整体生产。与以前的报道类似,姜黄素减少由病毒感染诱导的ROS的产生。然而,姜黄素的抗氧化特性并不有助于其抗病毒活性,因为N-乙酰-1-半胱氨酸,有效的抗氧化剂未能抑制病毒复制。这项研究还表明,细胞外信号调节激酶(ERK)被病毒感染或姜黄素治疗激活,但激活的ERK并不干扰姜黄素的抗病毒作用,表明ERK不参与姜黄素的抗病毒机制。与以前的报道,姜黄素通过泛素-蛋白酶体系统(UPS)抑制蛋白质降解不同,我们发现姜黄素对对照细胞中的UPS没有影响.然而,姜黄素确实降低了蛋白酶体的活性,而蛋白酶体的活性因病毒感染而增加。此外,短寿命蛋白质的积累,在EV71感染的细胞中,姜黄素的治疗使p53和p21增加。我们通过检测GBF1和PI4KB的表达进一步探讨了姜黄素的抗病毒机制。这两者都是病毒复制复合物形成所必需的。我们发现姜黄素显著降低两种蛋白质的水平。此外,通过应用siRNA降低GBF1或PI4KB的表达足以抑制病毒复制.我们还证明姜黄素在病毒感染的早期阶段显示出抗凋亡活性。这项研究的结果提供了坚实的证据表明姜黄素具有有效的抗EV71活性。姜黄素下调GBF1和PI4KB是否有助于其抗病毒作用尚需进一步研究。
Human enterovirus 71 (EV71) is the main causative pathogen of hand, foot, and mouth disease (HFMD) in children. The epidemic of HFMD has been a public health problem in Asia-Pacific region for decades, and no vaccine and effective antiviral medicine are available. Curcumin has been used as a traditional medicine for centuries to treat a diversity of disorders including viral infections. In this study, we demonstrated that curcumin showed potent antiviral effect again EV71. In Vero cells infected with EV71, the addition of curcumin significantly suppressed the synthesis of viral RNA, the expression of viral protein, and the overall production of viral progeny. Similar with the previous reports, curcumin reduced the production of ROS induced by viral infection. However, the antioxidant property of curcumin did not contribute to its antiviral activity, since N-acetyl-l-cysteine, the potent antioxidant failed to suppress viral replication. This study also showed that extracellular signal-regulated kinase (ERK) was activated by either viral infection or curcumin treatment, but the activated ERK did not interfere with the antiviral effect of curcumin, indicating ERK is not involved in the antiviral mechanism of curcumin. Unlike the previous reports that curcumin inhibited protein degradation through ubiquitin-proteasome system (UPS), we found that curcumin had no impact on UPS in control cells. However, curcumin did reduce the activity of proteasomes which was increased by viral infection. In addition, the accumulation of the short-lived proteins, p53 and p21, was increased by the treatment of curcumin in EV71-infected cells. We further probed the antiviral mechanism of curcumin by examining the expression of GBF1 and PI4KB, both of which are required for the formation of viral replication complex. We found that curcumin significantly reduced the level of both proteins. Moreover, the decreased expression of either GBF1 or PI4KB by the application of siRNAs was sufficient to suppress viral replication. We also demonstrated that curcumin showed anti-apoptotic activity at the early stage of viral infection. The results of this study provide solid evidence that curcumin has potent anti-EV71 activity. Whether or not the down-regulated GBF1 and PI4KB by curcumin contribute to its antiviral effect needs further studies.