Immune Responses in Acute Hepatitis C

描述（由申请人提供）：在美国，丙型肝炎病毒（HCV）是进行性肝炎、肝硬化和肝细胞癌的主要原因。了解允许大约15%的人清除急性丙型肝炎的免疫类型是开发疫苗的关键。在黑猩猩和人类中的探索性研究表明，靶向多种HCV蛋白的T细胞似乎是清除HCV所必需的。为了更好地了解与保护相关的免疫类型，需要仔细研究成功的反应。注射吸毒者的新丙型肝炎病毒感染率最高，但通常许多人会失去随访。在一个超过200名注射者的当地流行病学队列中，发现并随访了高新发HCV感染率（28%/人/年）。这使得对急性丙型肝炎患者的前瞻性研究成为可能。在本项目中，目标1提出从诊断的角度（基于HCV RNA或抗体阳性的转换）前瞻性地检查HCV特异性抗体和T细胞应答。将通过结合淋巴细胞增殖、细胞内细胞因子染色和ELISpot测定来确定HCV蛋白靶点以及CD 4 + T细胞和CD 8 + T细胞应答的活力。将进行定性和定量抗体分析，扩增HCV特异性CTL，检查其库，并精确绘制其表位和HLA限制性图谱。将合成一些HLA/肽表位的MHC I类四聚体，用于在消退者和进展者中更高分辨率地比较CTL库。假设肽表位内的进化导致病毒从CTL逃逸。该免疫逃逸模型将在目标2中测试，因为CTL表位变体在CTL测定中被测序、合成和测试。一个表位的变异范围仍然可以识别的CTL将构成一个合乎逻辑的疫苗成分。最近的实验表明，抑制性和激活性受体（NKR）阵列的HCV特异性CTL的表达。NKR配体库取决于人的HLA类型，这表明NKR+ CTL可能依赖于肝脏中的配体相互作用而受到调节。这将在目标3中得到检验。总的来说，这项调查将提供独特的见解免疫保护机制对HCV。这也将为疫苗设计奠定基础。

DESCRIPTION (provided by applicant): In the US, hepatitis C virus (HCV) is the leading cause of progressive hepatitis, cirrhosis and liver cell cancer. Understanding the type of immunity that allows approximately 15% people to clear acute hepatitis C holds the key to developing a vaccine. Exploratory studies in chimpanzee and humans show that T cells targeting multiple HCV proteins seem necessary for HCV clearance. To better understand the type of immunity that correlates with protection, careful study of successful responses will be required. Injection drug users have the highest rates of new HCV infection but typically many get lost to follow-up. In a local epidemiological cohort of over 200 injectors a high rate (28%/person/year) of new HCV infections has been identified and followed up. This now permits prospective study of people with acute hepatitis C. In this project, Aim 1 proposes to prospectively examine HCV-specific antibody and T cell responses from the point of diagnosis (based on conversion to HCV RNA or antibody positivity). The HCV protein targets and vigor of CD4+ T cell and CD8+ T cell responses will be determined by combining lymphoproliferation, intracellular cytokine staining, and ELISpot assays. Qualitative and quantitative antibody analysis will be conducted and CTL specific for HCV will be expanded, their repertoires examined and their epitopes and HLA restriction precisely mapped. MHC class I tetramers of some HLA/peptide epitopes will be synthesized for higher resolution comparison of CTL repertoires in resolvers and progressors. Evolution within peptide epitopes is hypothesized to result in viral escape from CTL. This model of immune escape will be tested in Aim 2, as CTL epitope variants are sequenced, synthesized and tested in CTL assays. An epitope whose ange of variants can still be recognized by CTL would constitute a logical vaccine component. Recent experiments have demonstrated expression of arrays of inhibitory and activating receptors (NKR) by HCV-specific CTL. The NKR ligand repertoire depends on the person's HLA type suggesting that NKR+ CTL may be variably regulated depending on ligand interaction in the liver. This will be tested in Aim 3. Overall this investigation will provide unique insights into protective mechanisms of immunity against HCV. It will also lay a foundation for vaccine design.