Development of Listeria-Based Clinical Consensus HCV Vaccine Candidates

描述（由申请人提供）：慢性丙型肝炎病毒（HCV）感染是世界许多地区肝功能衰竭和肝细胞癌的主要原因；全世界有1.7亿人慢性感染丙型肝炎病毒。目前治疗慢性丙型肝炎病毒的方法，如全身性α干扰素，价格昂贵且仅适用于少数感染者。慢性丙型肝炎病毒治疗是一个巨大的未满足的医疗需求。HCV已经发展出逃避免疫消除的机制，从而使其在大多数感染者的肝脏中持续存在。我们已经为北美、欧洲、日本和澳大利亚最常见的HCV基因型定义了一个HCV共识序列，并表明它可以被来自不同HCV序列个体的t细胞识别。该提案的总体目标是选择基于新型减毒活或杀伤但代谢活性（KBMA）单核细胞增生李斯特菌（Lm）平台的治疗性候选疫苗，该平台编码丙型肝炎病毒（HCV）共识序列抗原，准备在灵长类动物中进行l期毒理学和免疫原性研究，最终在慢性HCV感染的人类中进行试验。我们假设Lm将克服HCV的免疫逃避机制。Lm诱导促炎细胞因子级联反应，其标志是肝脏局部产生I型干扰素，导致器官中自然杀伤细胞（NK）和T细胞的优先积累和激活。我们假设，基于共识序列的HCV抗原与具有可接受安全性的Lm疫苗平台结合，自然靶向对病毒库的适应性和获得性免疫反应，将导致慢性HCV感染个体的有效治疗。具体而言，我们建议：(1)构建编码HCV核心蛋白、丝氨酸蛋白酶/解旋酶和RNA依赖性RNA聚合酶蛋白的Lm-HCV临床候选疫苗菌株；(2)选择减毒活疫苗株和KBMA Lm-HCV候选疫苗株，在非人灵长类动物中进行进一步研究，基于表征的HLA- a2限制性抗原和现有hcv特异性T细胞系的激活，以及在HLA- a2转基因小鼠中的免疫原性；(3)开发基于发酵罐的工艺方法，用于生产用于非人灵长类动物研究的减毒活疫苗和KBMA Lm-HCV候选疫苗菌株；(4)根据在狒狒中进行的免疫原性和毒性研究以及在慢性感染的黑猩猩中进行的初步治疗效果研究，选择减毒活疫苗或KBMA Lm-HCV疫苗方案继续开发。我们已经组建了一个由来自学术和生物技术机构的经验丰富的科学家组成的联盟，他们在新型疫苗平台开发和转化、传染病疫苗开发、非人类灵长类动物和人类的丙型肝炎病毒病毒学和免疫学研究方面具有专业知识，并且已经开展了富有成效的合作。

DESCRIPTION (provided by applicant): Chronic infection with hepatitis C virus (HCV) is the primary cause of liver failure and hepatocellular carcinoma in many parts of the world; 170 million individuals worldwide are chronically infected with HCV. Current therapies for chronic HCV, such as systemic alpha-interferon, are expensive and applicable only to a minority of infected individuals. Chronic HCV therapy represents a huge unmet medical need. HCV has developed mechanisms to evade immune elimination, thereby allowing it to persist in the liver in the majority of infected individuals. We have defined an HCV consensus sequence for the most common HCV genotype in North America, Europe, Japan, and Australia and have shown that it is recognized by T-cells from individuals with divergent HCV sequences. The overall goal of this proposal is to select therapeutic vaccine candidates based on novel live-attenuated or Killed But Metabolically Active (KBMA) Listeria monocytogenes (Lm)-based platforms encoding hepatitis C virus (HCV) consensus sequence antigens that are poised for Phase l-enabling toxicology and immunogenicity studies in primates for eventual testing in humans with chronic HCV infection. We hypothesize that Lm will overcome the mechanisms of immune evasion by HCV. Lm induces a pro-inflammatory cytokine cascade, whose hallmark is the localized production of type I interferon by the liver, resulting in preferential accumulation and activation of natural killer (NK) and T cells in the organ. We hypothesize that the combination of HCV antigens based on the consensus sequence together with an Lm vaccine platform with an acceptable safety profile that naturally targets the adaptive and acquired immune response to the virus reservoir will result in an effective therapy for individuals with chronic HCV infection. Specifically, we propose to: (1) Construct Lm-HCV clinical candidate vaccine strains that encode the consensus HCV core, serine proteinase/helicase, and RNA dependent RNA polymerase proteins; (2) Select live-attenuated and KBMA Lm-HCV candidate vaccine strains for further studies in nonhuman primates based on presentation of characterized HLA A2-restricted antigens and activation of existing HCV-specific T cell lines, and on immunogenicity in HLA-A2 transgenic mice; (3) Develop fermentor-based process methods for manufacture of live-attenuated and KBMA Lm-HCV candidate vaccine strain lots for use in nonhuman primate studies; and, (4) Select a live-attenuated or KBMA Lm-HCV vaccine regimen for continued development based on immunogenicity and toxicity studies performed in baboons and a pilot therapeutic efficacy study in chronically infected chimpanzees. We have assembled an experienced consortium of scientists from academic and biotechnology institutions with expertise in novel vaccine platform development and translation, infectious disease vaccine development, study of HCV virology and immunology in both nonhuman primates and humans, and an existing productive collaboration.