Hepatitis C virus genotype 3 NS5A protein: resistance to direct acting antiviral agents and functional analysis

丙型肝炎病毒是一种重要的人类病原体，据估计，全球有7000万人感染了这种病毒。最近，一些非常有效的抗病毒药物已经被开发出来，可以治愈受感染的人，但这些药物价格昂贵，而且病毒可能会变得具有抗药性。因此，有必要更好地了解病毒是如何生长和致病的，药物是如何起作用的，并最终开发出更多的抗病毒药物。丙型肝炎病毒是一种非常易变的病毒，目前已鉴定出7种不同的毒株(称为1-7型)。这个项目的重点是基因3，这是全球第二常见的基因，约占30%(约.2000万例)。基因3在中低收入国家(LMIC)最常见，占病例的44%，尤其是南亚(巴基斯坦、印度和泰国)70%的丙型肝炎病毒感染是基因3。与此一致，基因3在西欧部分地区也很常见，占英国丙型肝炎病例的44%。这一点很重要，因为与其他基因相比，基因3型感染与肝病进展更快、糖尿病、脂肪肝和肝癌的发病率更高以及死亡率更高有关。基因3患者也表现出对新药的高度抗药性，限制了治疗选择。基因3和其他基因类型之间的差异还不是很清楚，主要是因为直到最近还没有好的实验室系统来研究这种基因。我们试图解决这种缺乏知识的问题，特别是关注一种病毒蛋白NS5A，它在其他基因类型中被证明是病毒生长和疾病所必需的，也是一些新药的靶标。我们将利用我们在研究其他基因类型的NS5A方面的专业知识，以及我们和其他人开发的在细胞培养中培养3型病毒的新系统，来询问为什么它对药物如此抗药性以及NS5A是如何与细胞相互作用的。我们希望这些研究将阐明为什么3型丙型肝炎病毒如此不同，并为感染这种丙型肝炎病毒的患者开发新的治疗策略提供机会。

Hepatitis C virus (HCV) is an important human pathogen and it is estimated that 70 million people worldwide are infected with this virus. Recently a number of very effective antiviral drugs have been developed that can cure infected individuals, however these are expensive and the virus can change to become resistant. Thus there is a need to better understand how the virus grows and causes disease, how the drugs work and ultimately to develop more antivirals. HCV is a very variable virus and 7 distinct strains (termed genotypes 1-7) have been identified. This project focusses on genotype 3, the second most common genotype worldwide accounting for approximately 30% (approx. 20 million) of HCV cases. Genotype 3 is the most common in low to middle income countries (LMIC), accounting for 44% of cases and in particular, 70% of HCV infections in South Asia (Pakistan, India and Thailand) are genotype 3. Consistent with this, genotype 3 is also prevalent in parts of Western Europe, and accounts for 44% of HCV cases in the UK. This is important as genotype 3 infection is associated with a more rapid progression of liver disease, a higher incidence of diabetes, fatty liver and liver cancer, and a higher mortality rate compared to other genotypes. Genotype 3 patients also exhibit high levels of resistance to the new drugs, limiting the treatment options. The differences between genotype 3 and other genotypes are not very well understood, mainly because until recently there were no good laboratory systems available to study this genotype. We seek to address this lack of knowledge in particular focusing on one viral protein, NS5A, which has been shown in other genotypes to be required for virus growth and disease, as well as being a target for some of the new drugs. We will use our expertise in studying NS5A in other genotypes, together with new systems developed by us and others to grow genotype 3 virus in cell culture, to ask why it is so resistant to the drugs and how NS5A interacts with the cell. We hope that these studies will shed light on why genotype 3 is so different, and provide opportunities to develop new therapeutic strategies for patients infected with this genotype of HCV.