Chan Shiu-Wan
Shiu-Wan Chan, Faculty of Life Sciences, The University of Manchester, Manchester M13 9PT, United Kingdom.
World J Gastroenterol. 2014 Mar 21;20(11):2785-800. doi: 10.3748/wjg.v20.i11.2785.
Hepatitis C virus (HCV) causes a clinically important disease affecting 3% of the world population. HCV is a single-stranded, positive-sense RNA virus belonging to the genus Hepacivirus within the Flaviviridae family. The virus establishes a chronic infection in the face of an active host oxidative defence, thus adaptation to oxidative stress is key to virus survival. Being a small RNA virus with a limited genomic capacity, we speculate that HCV deploys a different strategy to evade host oxidative defence. Instead of counteracting oxidative stress, it utilizes oxidative stress to facilitate its own survival. Translation is the first step in the replication of a plus strand RNA virus so it would make sense if the virus can exploit the host oxidative defence in facilitating this very first step. This is particularly true when HCV utilizes an internal ribosome entry site element in translation, which is distinctive from that of cap-dependent translation of the vast majority of cellular genes, thus allowing selective translation of genes under conditions when global protein synthesis is compromised. Indeed, we were the first to show that HCV translation was stimulated by an important pro-oxidant-hydrogen peroxide in hepatocytes, suggesting that HCV is able to adapt to and utilize the host anti-viral response to facilitate its own translation thus allowing the virus to thrive under oxidative stress condition to establish chronicity. Understanding how HCV translation is regulated under oxidative stress condition will advance our knowledge on how HCV establishes chronicity. As chronicity is the initiator step in disease progression this will eventually lead to a better understanding of pathogenicity, which is particularly relevant to the development of anti-virals and improved treatments of HCV patients using anti-oxidants.
丙型肝炎病毒(HCV)引发一种临床上重要的疾病,影响着全球3%的人口。HCV是一种单链、正义RNA病毒,属于黄病毒科肝炎病毒属。面对宿主活跃的氧化防御机制,该病毒会建立慢性感染,因此适应氧化应激是病毒生存的关键。作为一种基因组容量有限的小RNA病毒,我们推测HCV采用了不同的策略来逃避宿主的氧化防御。它不是对抗氧化应激,而是利用氧化应激来促进自身生存。翻译是正义链RNA病毒复制的第一步,因此如果病毒能够利用宿主的氧化防御来促进这第一步,那是有道理的。当HCV在翻译过程中利用内部核糖体进入位点元件时尤其如此,这与绝大多数细胞基因的帽依赖性翻译不同,从而使得在整体蛋白质合成受损的条件下能够选择性地翻译基因。事实上,我们是第一个表明HCV翻译受到肝细胞中一种重要的促氧化剂——过氧化氢刺激的,这表明HCV能够适应并利用宿主的抗病毒反应来促进自身翻译,从而使病毒在氧化应激条件下得以增殖并建立慢性感染。了解HCV在氧化应激条件下的翻译调控机制将增进我们对HCV如何建立慢性感染的认识。由于慢性感染是疾病进展的起始步骤,这最终将有助于更好地理解致病性,这对于开发抗病毒药物以及使用抗氧化剂改善丙型肝炎患者的治疗尤为重要。