Development of a Proplylactic HCV Vaccine

描述(由申请人提供)：总体目标是开发丙型肝炎病毒(丙型肝炎病毒)特异性免疫原，可用作预防慢性丙型肝炎病毒感染的疫苗。在第一种方法(特定目标1)中，将开发一种使用颗粒载体平台递送包膜衍生的高变区1(HVR1)共识中和表位的丙型肝炎疫苗。修饰土拨鼠肝炎核心(WHcAg)颗粒将被用作疫苗平台，原因如下：杂交-WHcAg颗粒可产生极高水平的抗插入抗体；使用WHcAg不会影响抗-HBc诊断分析的使用，因为WHcAg和人类肝炎核心抗原(HBcAg)在抗体水平上不会发生交叉反应；使用WHcAg平台可以规避慢性乙肝携带者对HBcAg的免疫耐受，因为HBcAg和WHcAg只在T细胞水平上发生部分交叉反应；最近开发出一种比HBcAg更灵活的“WHcAg组合技术”，可以容纳更多种外来表位的插入。我们建议在WHcAg平台上插入源于E2可变区的共识中和序列，以解决丙型肝炎病毒的遗传变异性问题。WHcAg平台的一个重要优势是它由240个亚基组成，这些亚基可以自组装成粒子。因此，理论上可以将多个HVR1共识多肽插入到同一WHcAg-HVR1杂化颗粒中。在第二种方法(特定目标2)中，将设计和开发一种使用相同的WHcAg载体平台来传递E1-E2保守中和表位的丙型肝炎疫苗。开发丙型肝炎病毒预防性疫苗的一个重要问题是病毒的高度遗传变异性。除了多个HVR1共识表位外，另一种方法是确定遗传稳定或保守的表位或抗原区。因此，在E1或E2区域内发现的高度或半保守(跨基因型)中和表位，在自然感染期间免疫原性可能较差，将被插入到WHcAg平台上。通过检测免疫后产生的抗HVR1和抗E1/E2抗血清中和丙型肝炎病毒伪粒子感染的能力，对这些具有一致性和保守性的E1/E2-WHcAg杂合颗粒的免疫原性进行了分析。最后(具体目标3)我们建议在WHcAg平台上插入一个包含CD4和CD8表位的NS3区域，以扩大针对丙型肝炎病毒的免疫应答的效率。NS3的这个富含T细胞的结构域将被融合到杂交WHcAg平台的C末端。为了有效地诱导CTL反应，我们建议使用等价物-Boost策略。免疫系统将首先由编码丙型肝炎病毒-WHcAg-CD4+/CD8+平台的DNA疫苗启动，该平台也包含中和B细胞位点，然后我们将用同源的丙型肝炎病毒-WHcAg-CD4+/CD8+颗粒蛋白增强免疫。

DESCRIPTION (provided by applicant): The overall objective is to develop hepatitis C virus (HCV)-specific immunogens that may be useful as vaccines for the prevention of chronic HCV infection. In the first approach (Specific Aim 1), an HCV vaccine using a particulate carrier platform to deliver envelope-derived hypervariable region 1 (HVR1) consensus neutralizing epitopes will be developed. Modified woodchuck hepatitis core (WHcAg) particles will be used as a vaccine platform for several reasons: hybrid-WHcAg particles elicit extremely high levels of anti-insert antibodies; use of the WHcAg will not compromise the use of the anti-HBc diagnostic assay because the WHcAg and human hepatitis core antigen (HBcAg) are not crossreactive at the antibody level; the immune tolerance to HBcAg in HBV chronic carriers can be circumvented by the use of the WHcAg platform because the HBcAg and WHcAg are only partially crossreactive at the T cell level; a "WHcAg combinatorial technology" more versatile than the HBcAg in terms of accommodating the insertion of a greater variety of foreign epitopes has been recently developed. We propose to insert into the WHcAg platform consensus neutralizing sequences derived from the variable HVR1 region of E2 in order to address the problem of genetic variability of HCV. An important advantage of the WHcAg platform is that it is comprised of 240 subunits that self-assemble into particles. Therefore, multiple HVR1 consensus peptides can theoretically be inserted into the same WHcAg-HVR1 hybrid particle. In the second approach (Specific Aim 2) an HCV vaccine using the same WHcAg carrier platform to deliver E1-E2 conserved neutralizing epitopes will be designed and developed. An important problem in developing a prophylactic vaccine against HCV is the high genetic variability of the virus. In addition to multiple HVR1 consensus epitopes, an alternative approach is to identify epitopes or antigenic regions which are genetically stable or conserved. Therefore, highly or semi-conserved (across genotypes) neutralizing epitopes identified within the E1 or E2 domains, which may be poorly immunogenic during natural infection, will be inserted onto the WHcAg platform. The efficacy of these HVR1 consensus and conserved E1/E2-WHcAg hybrid particles will be analyzed for immunogenicity and characterized by testing the ability of the anti-HVR1 and anti-E1/E2 antisera generated by immunization to neutralize HCV pseudoparticle infection. Finally (Specific Aim 3) we propose to insert into the WHcAg platform a domain in NS3 containing CD4 and CD8 epitopes to broaden the efficiency of the immune response against HCV. This "T cell rich" domain of NS3 will be fused to the C-terminal of the hybrid-WHcAg platform. To efficiently induce a CTL response, we propose to use the equivalent of a prime-boost strategy. The immune system will be first primed by a DNA vaccine encoding the HCV-WHcAg-CD4+/CD8+ platform also containing neutralizing B cell sites, then we will boost with the homologous HCV-WHcAg-CD4+/CD8+ particulate protein.