Immune correlates of protection against hepacivirus persistence.

摘要 虽然直接作用的抗病毒药物可以治愈丙型肝炎病毒（HCV）感染，但疫苗是必要的，以阻止新的 感染，并防止治愈个体的再感染。对人类和黑猩猩的研究表明 T细胞和中和抗体（nAb）在清除HCV感染中起重要作用。 然而，由于缺乏动物模型，HCV疫苗开发的进一步进展受到阻碍。值得注意的是， 体液免疫和细胞免疫的性质、广度和相对作用决定了结果 对HCV感染的认识仍然很少。我们最近发现，一种大鼠肝炎病毒（HCV样病毒）， RHV具有HCV感染和免疫的特征。大多数完全免疫的大鼠 因此，大鼠是"概念验证"疫苗接种研究的适当模型， 预防HCV样病毒持续存在，这是HCV疫苗的预期目标。我们进一步验证了这个模型， 确定类似于在黑猩猩中进行的HCV研究报告，使用腺病毒疫苗接种大鼠， 表达RHV非结构（NS）蛋白的细胞产生部分保护作用， 同源RHV毒株（Nature Communications，PMC6405742）。有趣的是，我们观察到 接种疫苗的大鼠清除了同源病毒， 同源和异源病毒以及T细胞逃逸变体。这些结果表明，短- 长期病毒感染增强T细胞免疫或产生nAb，或两者兼有，以赋予有效免疫 对抗异源病毒最重要的是，这些结果对于定义 免疫力，赋予有效的保护，防止持续感染的遗传多样性病毒，如丙型肝炎病毒 变体。这个项目的总体目标是确定免疫相关的保护对肝炎病毒 持久性。具体目标-1是确定T细胞相关的保护对肝炎病毒的持久性。 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.具体目的-2是研究包膜蛋白（E1/E2）诱导免疫的作用和重要性 nAbs在病毒清除中的作用。我们的假设是，使用NS和 E1E2疫苗将增加对病毒持续存在的免疫力。具体目标-3是确定 疫苗诱导的免疫力，并确定疫苗失败的病毒决定因素。我们的假设是 疫苗接种可以防止仅共享少数T细胞表位的遗传多样性病毒的持续存在。的 建议解剖疫苗和短期病毒感染赋予的免疫力是必要的了解 T和B细胞在肝病毒清除中的相对作用，这一知识有助于 一个有效的疫苗接种策略。最后，T和B的拟议表征 这种终身持续RNA病毒感染的独特模型中的细胞免疫将为测试新的 疫苗接种方法（如RNA疫苗），以预防慢性病毒感染。

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.