Immune correlates of protection against hepacivirus persistence.

摘要 尽管直接作用的抗病毒药物可以治愈丙型肝炎病毒(丙型肝炎病毒)感染，但必须接种疫苗才能阻止新的 感染，并防止被治愈的个体再次感染。对人类和黑猩猩的研究表明 T细胞和中和抗体(NAB)在清除丙型肝炎病毒感染中均可发挥重要作用。 然而，由于缺乏动物模型，丙型肝炎疫苗开发的进一步进展一直受到阻碍。值得注意的是， 体液免疫和细胞免疫在决定预后中的性质、广度和相对贡献 对丙型肝炎病毒感染的原因仍知之甚少。我们最近发现了一种大鼠肝炎病毒(丙型肝炎病毒样病毒)， 人巨噬细胞病毒具有丙型肝炎病毒感染和免疫的特征。大多数完全免疫功能正常的大鼠 终生病毒持续存在，因此大鼠是进行概念验证疫苗研究的合适模型 预防类似丙型肝炎病毒的病毒持久性，这是丙型肝炎疫苗的预期目标。我们通过以下方式进一步验证了该模型 确定与丙型肝炎病毒在黑猩猩身上的研究报告一样，使用腺病毒接种的大鼠 表达RHV非结构(NS)蛋白可部分保护A型肝炎病毒持续存在 同源RHV株(自然通讯，PMC6405742)。有趣的是，我们观察到 清除同源病毒的免疫大鼠产生了更有效和更广泛的免疫力 同源和异源病毒以及T细胞逃逸变异体。这些结果表明，短期- 长期病毒感染要么增强T细胞免疫，要么产生nabs，或者两者兼而有之，以提供有效的免疫力 对抗异源病毒。最重要的是，这些结果很有希望定义 免疫，提供有效的保护，防止持续感染遗传多样性的病毒，如丙型肝炎病毒 变种。这个项目的总体目标是确定预防肝炎病毒的免疫相关因素。 坚持不懈。具体目的-1是定义T细胞与预防肝炎病毒持续存在的相关性。 我们的假设是，病毒特异性T细胞的性质和广度决定了肝炎病毒的命运 感染。特异的目的-2是研究包膜蛋白(E1/E2)诱导免疫的作用和重要性 在清除病毒的过程中。我们的假设是，使用NS和联合接种疫苗的方法 E1E2疫苗将提高对病毒持久性的免疫力。具体目标是定义-3\f25 疫苗诱导免疫，并确定疫苗失败的病毒决定因素。我们的假设是 接种疫苗可以防止遗传多样性的病毒持续存在，这些病毒只有几个T细胞表位。这个 建议解剖疫苗和短期病毒感染授予的免疫是必要的，以了解 T和B细胞在清除肝炎病毒中的相对作用，这一知识有助于 构思有效的丙型肝炎疫苗接种策略。最后，提出了T和B的刻画 细胞免疫在这种独特的终身持续RNA病毒感染模式中将为测试新的 预防慢性病毒感染的疫苗接种方法(如RNA疫苗)。

Abstract Although direct acting antivirals can cure Hepatitis C virus (HCV) infection, a vaccine is necessary to stop new infections, and to prevent re-infections in the cured individuals. Studies in humans and chimpanzees suggest that both T cells and neutralizing antibodies (nAb) can play an important role in the clearance of HCV infection. However, further progress on HCV vaccine development has been stymied by a lack of animal models. Notably, the nature, breadth, and relative contribution of humoral and cellular immunity in determining the outcomes of HCV infection remain poorly understood. We recently showed that a rat hepacivirus (HCV-like virus), RHV, shares the hallmarks of HCV infection and immunity. A majority of fully-immunocompetent rats develop lifelong viral persistence, and thus rats are appropriate models for “proof-of-concept” vaccination studies to prevent HCV- like viral persistence, the desired goal of HCV vaccines. We further validated this model by determining that like reported from HCV studies in chimpanzees, rats vaccinated using an Adenovirus expressing RHV non-structural (NS) proteins develop partial protection against persistence of a homologous RHV strain (Nature communications, PMC6405742). Interestingly, we observed that the vaccinated rats that cleared a homologous virus developed more efficient and broader immunity for homologous and heterologous viruses, and T cell escape variants. These results suggest that the short- term viral infection either enhances T cell immunity or generates nAbs, or both, to confer effective immunity against heterologous viruses. Most importantly, these results are promising for defining the nature of immunity that confers effective protection against persistent infection of genetically diverse viruses, like HCV variants. The overall goal of this project is to define the immune correlates of protection against hepacivirus persistence. Specific aim-1 is to define the T cell correlates of protection against hepacivirus persistence. Our hypothesis is that the nature and breadth of virus-specific T cells determines the fate of hepacivirus infections. Specific aim-2 is to study the role of envelope proteins (E1/E2) induced immunity and importance of nAbs in virus clearance. Our hypothesis is that a vaccination approach using a combination of NS and E1E2 vaccines will increase the immunity against viral persistence. Specific Aim- 3 is to define the breadth of vaccine induced immunity, and to identify the viral determinants of vaccine failure. Our hypothesis is that vaccination can prevent persistence of genetically diverse viruses that share only a few T cell epitopes. The proposed dissection of vaccine and short-term viral infection conferred immunity is necessary to understand the relative contributions of T and B cells in hepacivirus clearance, and this knowledge can help in conceptualizing an effective vaccination strategy for HCV. Finally, the proposed characterization of T and B cell immunity in this unique model of life-long persistent RNA virus infection will pave the way for testing of newer vaccination approaches (like RNA vaccines) to prevent chronic virus infection.