Hepacivirus control by T cells and broadly active antibodies

丙型肝炎病毒(丙型肝炎病毒)是全球范围内导致肝硬变和肝细胞癌的主要原因， 据估计，每年有1.85亿人感染，超过35万人死亡。在发达国家，注射毒品 使用是主要的传播途径，占美国丙型肝炎病毒感染的三分之二以上， 高达80%的注射吸毒者感染了丙型肝炎病毒。尽管新的直接作用抗病毒药物将发挥 在控制丙型肝炎病毒方面发挥重要作用，但治疗不太可能降低全球感染率，因为成本高， 因为大多数人是亚临床感染，不会寻求治疗。一种保护性疫苗将会是 更具成本效益，但保护性免疫的相关性尚不完全清楚。重要的是，丙型肝炎病毒 只感染人类和黑猩猩，而且由于对黑猩猩的研究已经被逐步淘汰， 必须在另一种动物模型中严格剖析保护性免疫机制。最近，一位 新的非灵长类肝炎病毒已经在马身上被描述出来。这种马肝炎病毒(EHCV)是嗜肝性的 是已知的与丙型肝炎病毒最接近的亲缘关系。 这项拟议研究的总体目标是描绘病毒特异性记忆T的保护作用 抗肝炎病毒感染的细胞和抗体。需要测试的假设是，能够分解EHCV的马 感染启动广泛活跃的记忆T细胞和/或抗体反应，足以控制同源 和异源复制。我们将使用我们已建立的方法首先鉴定EHCV蛋白 含有由记忆T细胞识别的保守表位，这些表位来自已自发分解的马 原发E丙型肝炎病毒感染。具有高EHCV特异性增殖反应的记忆CD4+T细胞株将是 在培养中扩增，就像产生具有细胞毒活性的记忆γ+T细胞一样。 这些T细胞随后将被转移到患有严重联合免疫缺陷(SCID)的MHC匹配的马体内 并确定了对混合EHCV挑战的保护作用。然后我们将以同样的方式确定抗体 广泛抑制与马CD81结合的EHCVE2糖蛋白对EHCV2糖蛋白的攻击具有保护作用。 这些拟议的研究将明确证明病毒特异性T细胞和/或 抗体可以独立控制EHCV感染，并将对丙型肝炎疫苗的设计产生关键影响， 在那里这种类型的实验是不可能的。

Hepatitis C virus (HCV) is a leading cause of cirrhosis and hepatocellular carcinoma worldwide, with an estimated 185 million people infected and over 350,000 deaths a year. In developed countries, injection drug use is the predominant route of transmission and accounts for over two thirds of the HCV infections in the U.S., with up to 80% of injection drug users infected with HCV. Although new direct acting antiviral drugs will play an important role in controlling HCV, treatment is not likely to reduce global prevalence due to the high cost and because most people are subclinically infected and will not seek treatment. A protective vaccine would be much more cost-effective, but the correlates of protective immunity are not completely understood. Importantly, HCV only infects humans and chimpanzees, and because research on chimpanzees has been phased out, mechanisms of protective immunity must be rigorously dissected in an alternative animal model. Recently, a novel nonprimate hepacivirus has been described in horses. This equine hepacivirus (EHCV) is hepatotropic and is the closest known phylogenetic relative to HCV. The overall goal of the proposed studies is to delineate the protective roles of viral-specific memory T cells and antibodies against hepaciviral infection. The hypothesis to be tested is that horses that resolve EHCV infection mount broadly active memory T cell and/or antibody responses that are sufficient to control homologous and heterologous EHCV replication. We will use our established methods to first identify EHCV proteins containing conserved epitopes recognized by memory T cells from horses that have spontaneously resolved primary EHCV infection. Memory CD4+ T cell lines with high EHCV-specific proliferative responses will be expanded in culture, as will EHCV-specific IFNγ producing memory CD8+ T cell lines with cytotoxic activity. These T cells will then be transferred into MHC-matched horses with severe combined immunodeficiency (SCID) and protective effects against a mixed EHCV challenge determined. We will then similarly determine if antibodies that broadly inhibit EHCV E2 glycoprotein binding to equine CD81 are protective against EHCV challenge. These proposed studies will definitively demonstrate whether or not virus-specific T cells and/or antibodies can independently control EHCV infection and will have critical implications for HCV vaccine design, where experiments of this type are not possible.