Towards a Novel Strategy Against HBV Infection

描述（由申请人提供）：长期目标是开发一种新的HBV抗病毒策略，当与现有抗病毒药物联合使用时，将为慢性感染患者提供更有效的治疗。现有的抗病毒药物靶向逆转录。第二种方法是利用干扰素治疗，但效果较差且副作用显著。其他的方法提出了反义、核酶、细胞因子和最近的siRNA。然而，由于缺乏对HBV如何附着和进入易感细胞的了解，病毒附着和进入应该是一个高度可及的靶点，在很大程度上被忽视了。考虑到这一缺陷，三个特定目标是针对病毒组装、附着、进入和基因组复制起始等尚未解决的重要问题。这些研究将利用人类乙型肝炎病毒（HBV）的天然卫星——人丁型肝炎病毒（HDV）的组装依赖于HBV包膜蛋白（HBsAg）这一事实。已有数据支持HBV和HDV使用相同（或至少非常相似）的附着和进入易感细胞的机制这一合理假设。我们的策略是利用测定HDV基因组复制作为成功进入的指标的优势来检验这一机制。目的如下：(i)建立控制HDV组装的条件，并评估在两种不同的肝细胞系统中实现附着、进入和开始复制的能力。（ii）使用未修饰和/或修饰形式的HBV包膜蛋白进行病毒粒子组装，并确定HDV附着、进入和开始复制所需的决定因素。（iii）测试小分子对附着和进入的干扰，并朝着开发高通量筛选分析的方向发展。总体而言，Specific Aims 1和2中提出的研究提供了与HBV（和HDV）如何能够附着并进入易感细胞并开始复制相关的新的重要信息。这一信息反过来又可能导致Specific Aim 3在一个或多个步骤中开发感染抑制剂。然后，在与stresgen Biotechnologies的合作下，开发的检测方法将用于筛选多种化合物以提高疗效，并最终进入临床研究。

DESCRIPTION (provided by applicant): The long-term goal is to develop a novel HBV antiviral strategy, that when used in combination with existing antiviral agents, will provide a more powerful therapy for treating chronically infected patients. Existing antivirals target reverse transcription. A second approach, but less effective and with significant side-effects, utilizes interferon therapy. Other approaches have suggested antisense, ribozymes, cytokines, and more recently siRNA. However, what should be a highly accessible target, virus attachment and entry, has been largely ignored, primarily due to lack of understanding as to how HBV actually attaches to and enters susceptible cells. With this deficit in mind, three Specific Aims are directed at important unsolved issues of virus assembly, attachment, entry, and the initiation of genome replication. These studies will exploit the fact that the assembly of human hepatitis delta virus (HDV), a natural satellite of human hepatitis B virus (HBV), is dependent upon HBV envelope proteins (HBsAg). There are already data to support the reasonable assumption that HBV and HDV use the same (or at least a very similar) mechanism for attachment and entry into susceptible cells. The strategy is to examine this mechanism exploiting the advantages of assaying HDV genome replication as the indicator for successful entry. The aims are as follows: (i) Establish conditions for the controlled assembly of HDV and evaluate in two different hepatocyte systems the ability to achieve attachment, entry, and the initiation of replication. (ii) Use unmodified and/or modified forms of HBV envelope proteins for virion assembly, and identify of determinants necessary for attachment, entry, and initiation of HDV replication. (iii) Test small molecules for interference with attachment and entry, and move towards the development of high throughput screening assays. Overall, the studies proposed in Specific Aims 1 and 2 provide new and important information relevant to how HBV (and HDV) are able to attach to and then enter and initiate replication in susceptible cells. This information in turn could lead in Specific Aim 3 to the development of inhibitors of infection at one or more steps. Then, in collaboration with Stressgen Biotechnologies, the developed assays will be used to screen multiple compounds to increase efficacy, and ultimately move to clinical studies.