Dynamics of antigen specific B and Tfh responses during acute and chronic HCV

项目摘要/摘要： 治疗慢性丙型肝炎病毒感染现在非常有效。直接作用的抗病毒药物(DAA)通常是安全的 大多数持续性感染通过2-3个月的治疗就能治愈。然而，控制慢性肝炎的策略 仅靠抗病毒治疗是复杂的，有两个因素。首先，尽管抗病毒疗法有所改进 在过去的25年里，慢性丙型肝炎的治愈率仍然非常低 在美国和全球。几乎所有未经治疗的人(美国有300万人，全球有1.8亿人)都不知道 他们的持续感染；通常没有丙型肝炎病毒感染的症状，直到进行性肝病 显然是在接触病毒多年后出现的。其次，丙型肝炎病毒在大多数地区的传播速度加快。 整个世界。在美国，由于持续流行的注射毒品，感染率在过去十年里有所上升 在青少年和年轻人中使用。新的未确诊的丙型肝炎病毒感染几乎肯定会在 这一速度超过了检测和抗病毒治疗。疫苗可以帮助阻止丙型肝炎病毒的传播，然而 缺乏对保护相关因素的全面了解。虽然早期出现的广泛中和 抗体(BNAbs)通常与更有利的感染结局相关，即无法分离出丙型肝炎病毒- 分析特定B细胞的表型、功能、受体谱系、基因表达和中和 广度阻碍了对决定感染结果的分子机制的理解。我们 已经开发出一种新的四聚体，可以检测感染患者中的丙型肝炎病毒E2糖蛋白特异性记忆B细胞 感染了丙型肝炎病毒。这项资助的目的是确定丙型肝炎病毒特异性B细胞克隆选择的纵向变化 以及由丙型肝炎病毒特异性的CD4+T滤泡辅助细胞(TFH)之间相互作用产生的bNAbs的广度 和丙型肝炎病毒特异性B细胞。我们的中心假设是快速诱导丙型肝炎病毒特异的Tfh细胞反应 加快丙型肝炎病毒特异性B细胞克隆的选择和扩增，产生有助于 感染的消退。我们的特定目标将测试：纵向分离的丙型肝炎病毒特异性B细胞是否 来自自发解决者的细胞水平更活跃，克隆集中，并产生更多的抗体 中和广度高于来自持续感染患者的丙型肝炎病毒特异性B细胞(目标1)；早期增加 自发解决者急性感染时TFH细胞活性直接影响TFH细胞的快速克隆性扩增 丙型肝炎病毒特异性B细胞和随后的bNAb产生(目标2)。这项研究做出了重大贡献 以疫苗为基础的方法，旨在预防初次丙型肝炎病毒感染和/或再感染。

PROJECT SUMMARY/ABSTRACT: Treatment for chronic HCV infection is now highly effective. Direct Acting Antivirals (DAA) are generally safe and most persistent infections are cured with 2-3 months of therapy. However, a strategy to control chronic hepatitis C by antiviral therapy alone is complicated by two factors. First, although antiviral therapies have improved steadily over the past 25 years, the percentage of individuals cured of chronic hepatitis C is still remarkably low in the US and globally. Almost all untreated individuals (3 million in the US, 180 million globally) are unaware of their persistent infection; there are often no symptoms of HCV infection until progressive liver disease becomes apparent many years after exposure to the virus. Second, HCV transmission has accelerated in most regions of the world. In the US, infection rates increased over the past decade because of ongoing epidemic injection drug use amongst adolescents and young adults. New undiagnosed HCV infections will almost certainly develop at a rate that outpaces detection and antiviral cure. A vaccine could help stem HCV transmission, however a complete understanding of correlates of protection is lacking. While an early appearance of broadly neutralizing antibodies (bNAbs) generally correlates with a more favorable infection outcome, the inability to isolate HCV- specific B cells to dissect their phenotype, function, receptor repertoire, gene expression and neutralization breadth has hindered the understanding of the molecular mechanisms that determine infection outcome. We have developed a novel tetramer that detects HCV E2 glycoprotein-specific memory B cells in patients infected with HCV. The objective of this grant is to define the longitudinal changes in HCV-specific B cell clonal selection and the breadth of bNAbs resulting from the interplay between HCV-specific CD4+ T follicular helper cells (Tfh) and HCV-specific B cells. Our central hypothesis is that a rapid induction of the HCV-specific Tfh cell response accelerates the selection and expansion of HCV-specific B cell clones producing bNAbs that contribute to resolution of infection. Our specific aims will test whether: HCV-specific B cells isolated longitudinally at single cell level from spontaneous resolvers are more activated, clonally focused and produce antibodies with greater neutralization breadth than HCV-specific B cells from persistently-infected patients (Aim 1); an early increase in Tfh cell activity during acute infection in spontaneous resolvers directly influences the rapid, clonal expansion of HCV-specific B cells and subsequent bNAb production (Aim 2). This study makes a significant contribution towards a vaccine-based approach designed to prevent primary HCV infection and/or reinfection.