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（HCV）特异性免疫原，可用作预防慢性HCV感染的疫苗。在第一种方法（特异性目标1）中，将开发使用颗粒载体平台递送HCV衍生的高变区1（HVR 1）共有中和表位的HCV疫苗。修饰的土拨鼠肝炎核心（WHcAg）颗粒将用作疫苗平台，原因如下：混合WHcAg颗粒引发极高水平的抗插入物抗体;使用WHcAg不会影响抗HBc诊断测定的使用，因为WHcAg和人肝炎核心抗原（HBcAg）在抗体水平上没有交叉反应性; HBV慢性携带者对HBcAg的免疫耐受可通过使用WHcAg平台来规避，因为HBcAg和WHcAg在T细胞水平上仅部分交叉反应;最近开发了一种在适应更多种类的外源表位的插入方面比HBcAg更通用的“WHcAg组合技术”。我们建议在WHcAg平台中插入来自E2可变HVR 1区的共有中和序列，以解决HCV遗传变异性的问题。WHcAg平台的一个重要优势是它由240个自组装成颗粒的亚基组成。因此，理论上可以将多个HVR 1共有肽插入到同一WHcAg-HVR 1杂交颗粒中。在第二种方法（特异性目标2）中，将设计和开发使用相同WHcAg载体平台递送E1-E2保守中和表位的HCV疫苗。开发针对HCV的预防性疫苗的一个重要问题是病毒的高遗传变异性。除了多个HVR 1共有表位之外，另一种方法是鉴定遗传稳定或保守的表位或抗原区域。因此，在E1或E2结构域内鉴定的高度或半保守（跨基因型）中和表位（在自然感染期间可能免疫原性较差）将被插入WHcAg平台。将分析这些HVR 1共有和保守E1/E2-WHcAg杂交颗粒的免疫原性，并通过检测免疫产生的抗HVR 1和抗E1/E2抗血清中和HCV假颗粒感染的能力来表征。最后（具体目标3），我们提出在WHcAg平台中插入含有CD 4和CD 8表位的NS 3中的结构域，以扩大针对HCV的免疫应答的效率。NS 3的这种“富含T细胞”的结构域将融合到杂交-WHcAg平台的C末端。为了有效地诱导CTL应答，我们建议使用相当于引发-加强策略。免疫系统将首先由编码HCV-WHcAg-CD 4 +/CD 8+平台的DNA疫苗引发，该平台还含有中和B细胞位点，然后我们将用同源HCV-WHcAg-CD 4 +/CD 8+颗粒蛋白加强。

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.