Correlates of protective immunity to HCV and rational vaccine design

摘要 预防HCV感染仍然是一个重要的公共卫生目标，即使最近通过了 高效的抗病毒疗法重要的是，直接作用抗病毒药物（DAA）治疗 并不能防止那些已经成功治疗的人再次感染。预防HCV的疫苗 需要坚持不懈，以遏制青少年和年轻人中新出现的感染流行病， 接受筛查和治疗的机会有限的注射毒品。只有百分之二十五的急性 HCV感染会自行消退。然而，解决方案确实大大降低了持续的风险。 再次暴露于病毒时感染。记忆性CD4+ T辅助细胞和CD8+细胞毒性T细胞应答 有助于加速清除第二次感染。然而，中和抗体的作用 在再感染时的情况不太清楚。重要的是，产生等效T细胞反应的疫苗未能 阻止幼稚接受者的持续率。在这里，我们将测试中心假设， 记忆性CD4+ T细胞通过促进HCV的扩增， HCV特异性B细胞和产生有助于病毒清除的广泛中和抗体。 这项建议的独特之处是：（一）使用来自蒙特利尔高收入群体的纵向样本， 让注射毒品的人冒风险在HCV感染之前、期间和之后监测参与者， 然后，当他们再次暴露于HCV后， 解决他们的原发感染(ii)我们在埃及开罗召集了一个调查小组， 将帮助我们招募和治疗接受DAA治疗的受试者。埃及拥有最高的 HCV感染在世界范围内的流行情况。2014年，埃及政府将DAA待遇 负担得起，250万名受试者已开始接受治疗。了解免疫反应 这两个队列将为我们提供有价值的信息，以开发有效的疫苗方案， 这将模仿在HCV自然攻击期间产生的成功应答。 提出了三个高度互动的项目。项目1（N. Shoukry，PI）将比较频率， HCV再感染中CD4+ T细胞的宽度、功能和表型， 坚持不懈项目2（A. Grakoui，PI）将使用最先进的新技术来分离和 在HCV再感染期间和DAA治疗后表征抗原特异性B细胞。项目3（R. 阿马拉，PI）将开发疫苗模式，以诱导CD4+ T辅助反应和稳健的免疫应答。 使用DNA、改良的安卡拉牛痘（MVA）和 在非人灵长类动物中针对HCV蛋白的基于蛋白的疫苗。

Abstract Prevention of HCV infection remains an important public health objective even with the recent adoption of highly effective antiviral therapies. Importantly, treatment with direct acting antivirals (DAAs) does not prevent reinfection in those who have successfully been treated. A vaccine to prevent HCV persistence is needed to stem an emerging epidemic of infection in adolescents and young adults who inject drugs that have limited access to screening and treatment. Only twenty five percent of acute HCV infections resolve spontaneously. Resolution does, however, sharply reduce the risk of persistent infection upon re-exposure to the virus. Memory CD4+ T helper and CD8+ cytotoxic T cell responses contribute to accelerated clearance of a second infection. However, the role of neutralizing antibodies during reinfection is less clear. Importantly, vaccines to generate an equivalent T cell response failed to thwart off the rate of persistence in naïve recipients. Here, we will test the central hypothesis that memory CD4+ T cells contribute significantly to HCV reinfection outcome by promoting expansion of HCV-specific B cells and production of broadly neutralizing antibodies that contribute to viral clearance. Unique features of this proposal are (i) the use of longitudinal samples from the Montreal cohort of high- risk people who inject drugs. Participants are monitored prior to, during, and after HCV infection and then subsequently followed again when they have been re-exposed to HCV a second time after resolving their primary infection. (ii) We have assembled a team of investigators in Cairo, Egypt who will assist us with recruiting and treating subjects undergoing DAA treatment. Egypt has the highest prevalence of HCV infection in the world. In 2014, Egypt's government has made DAA treatment affordable and 2.5 million subjects have started treatment. Understanding the immune responses in these two cohorts will provide us with valuable information to develop an efficacious vaccine regimen that would emulate the successful responses generated during a natural challenge with HCV. Three highly interactive Projects are proposed. Project 1 (N. Shoukry, PI) will compare the frequency, breadth, function, and phenotype of CD4+ T cells in HCV reinfections that either resolve or become persistent. Project 2 (A. Grakoui, PI) will use new state of the art technology to isolate and characterize antigen-specific B cells during HCV reinfection and post DAA treatment. Project 3 (R. Amara, PI) will develop vaccine modalities to induce both a CD4+ T helper response and a robust antigen-specific antibody response in blood and liver using DNA, modified vaccinia Ankara (MVA) and protein-based vaccines against HCV proteins in non-human primates.