A Cytomegalovirus-based therapeutic vaccine for chronic hepatitis B

摘要 虽然有效的预防性疫苗可用于B型肝炎病毒（HBV），但慢性B型肝炎（CH B） 全世界有多达3.5亿人受到这种疾病的影响，尽管取得了进展，但大多数仍然无法治愈。成人，急性 HBV感染在95%的病例中通过CD 8 + T细胞介导的机制清除，但慢性终身感染 在剩余的个体中，这可能导致肝硬化和癌症。诱导和 通过传统的疫苗方法在感染个体的肝脏中维持HBV特异性T细胞， 由于免疫耐受性的挑战，CHB的标志之一。为了克服这些挑战，我们 将使用CMV载体平台来提供能够招募扩展集的持续抗原呈递 新的HBV特异性T细胞群有望解决这一问题。CMV载体HBV 疫苗具有几个独特的特征。1)它们可以被编程以引出常规的（MHC-I限制的） 和识别大量表位的非常规（MHC-II和MHC-E限制性）CD 8 + T细胞 2）CMV载体将引发并维持高频率的非耗尽效应子; 血液和肝脏中的记忆T细胞; 3）CMV载体通过逃避免疫应答来克服预先存在的抗CMV免疫力。 载体特异性免疫应答; 4）使用限定的减弱维持免疫诱导特征; 5)我们基于“epigraph”算法的抗原设计通过整合数据来解释全球基因型变异 来自全球3000多个HBV序列。我们假设基于CMV的HBV免疫治疗将导致 由于新的HBV特异性CD 8 + T细胞的募集，CHB的控制和免疫治愈。我们的目标是 在慢性感染者中测试这一假设，我们预计接种一种或两种疫苗 注射将导致HBV的终身免疫控制。在这个快速通道计划的第一阶段，我们将首先 设计、构建和表征表达HBV抗原的扩散缺陷型HCMV载体， 表位覆盖率。我们将两种互补的HBV“表位基”抗原插入安全性增强的HCMV中， 通过BAC重组工程改造载体以产生最终的HCMV/HBV构建体， 临床发展。在第2阶段计划中，我们将生成准备用于GMP的预主病毒种子储备液 生产和优化HCMV/HBV载体的生产工艺。我们将描述 HCMV/HBV疫苗在多次传代后的稳定性、抗原表达的维持和 基因组完整性然后，我们将描述疫苗和非人HBV特异性T细胞应答的特征。 灵长类动物（NHP）。我们将用HCMV/HBV免疫NHP，以确定有效剂量、时间和剂量。 抗原特异性T细胞应答的大小。我们将进一步确定的广度和应变特异性 使用代表不同HBV基因型的肽，在尸检时检测外周和肝脏T细胞。后 完成这些目标后，我们将产生并表征一种新的HBV免疫疗法， 可用于GMP生产和人体安全性和有效性研究。

Abstract Although an efficient prophylactic vaccine is available for hepatitis B virus (HBV), chronic hepatitis B (CHB) affects up to 350 million people worldwide, and despite advances remains mostly incurable. In adults, acute HBV infection is cleared in 95% of cases by CD8+ T cell-mediated mechanisms, but chronic, lifelong infection ensues in the remaining individuals, which can lead to liver cirrhosis and cancer. The induction and maintenance of HBV-specific T cells in the liver of infected individuals by traditional vaccine methods has been a challenge due to immunological tolerance, one of the hallmarks of CHB. To overcome these challenges, we will use a CMV vector platform to provide persistent antigen presentation capable of recruiting an expanded set of new HBV-specific T cell populations that are expected to circumvent this problem. CMV-vectored HBV vaccines have several unique features. 1) They can be programmed to elicit conventional (MHC-I restricted) and unconventional (MHC-II and MHC-E-restricted) CD8+ T cells that recognize a larger number of epitopes than traditional vaccines; 2) CMV vectors will elicit and maintain high frequencies of non-exhausted effector memory T cells in the blood and liver; 3) CMV vectors overcome pre-existing anti-CMV-immunity by evading vector-specific immune responses; 4) Use of defined attenuations maintain the immunological induction profile; 5) Our “epigraph”-algorithm-based antigen design accounts for global genotype variations by integrating data from over 3000 worldwide HBV sequences. We hypothesize that CMV-based HBV immunotherapy will lead to control and immunologic cure of CHB due to the recruitment of novel HBV-specific CD8+ T cells. Our goal is to test this hypothesis in chronically infected humans, in which we expect that vaccination with either one or two injections will result in lifelong immune control of HBV. In the Phase 1 of this Fast Track Program we will first design, construct and characterize a spread-deficient HCMV vector expressing HBV antigens with global epitope coverage. We will insert two complementary HBV “episensus” antigens into a safety-enhanced HCMV- vector through BAC recombineering to generate the final HCMV/HBV construct that can be taken forward for clinical development. In the Phase 2 program we will generate a pre-master virus seed stock ready for GMP production and optimize the manufacturing process of HCMV/HBV vectors. We will characterize the HCMV/HBV vaccine with respect to stability upon multiple passages, maintenance of antigen expression and genomic integrity. We will then characterize the vaccine and the HBV-specific T cell responses in non-human primates (NHP). We will immunize NHP with HCMV/HBV to determine the effective dose, the timing, and the magnitude of the antigen-specific T cell response. We will further determine the breadth and strain-specificity of peripheral and liver T cells upon necropsy using peptides representative of different HBV genotypes. Upon completion of these Aims we will have generated and characterized a novel immunotherapy for HBV that is ready for GMP manufacture and for human safety and efficacy studies.