Plant-derived vaccines against hepatitis C Cooperative *

描述（由申请人提供）：免疫学和病毒学研究在设计有效预防丙型肝炎感染的疫苗方面取得了巨大进展，但需要多学科的努力才能使这些设计最终生产出具有成本效益的全球免疫疫苗。这个拟议的合作研究中心（CRC）将严格评估一种新的方法来生物制造HCV抗原，已知可诱导对HCV的特异性免疫反应-通过人类临床研究确定，并预测在病毒清除中很重要-并评估这些抗原在适当的体外和体内模型系统中的反应。该CRC的一位联合主任领导了Chiron公司发现HCV重组抗原；对他目前在临床试验中可用的蛋白质套件的评估表明，预防性和免疫治疗性疫苗是可行的。不幸的是，至少从公共卫生市场生产的角度来看，最佳疫苗应该由多种抗原的“鸡尾酒”组成，以引发抗体介导和T细胞介导的免疫反应。生产这种疫苗可能需要两种单独的蛋白质表达系统，其中一种受到低产量的限制，这给商业开发——尤其是全球使用——带来了障碍。为了克服这些生产限制，本CRC建议快速利用当前对重要疫苗成分特性的了解来开发和验证一种新的多种HCV抗原的生物制造系统。这个提议的CRC的一个独特的特点是使用绿色植物作为重组蛋白的多功能，高成本效益的生产系统。拟议的研究是一种互动伙伴关系，利用Chiron的疫苗开发专业知识，对一个学术团队生产的HCV候选疫苗进行严格评估，该团队在十多年来率先将植物生物技术用于亚单位疫苗生产。

DESCRIPTION (provided by applicant): Research in immunology and virology has made enormous progress toward the design of an effective vaccine to prevent Hepatitis C infection, but multidisciplinary efforts are needed to move these designs to the ultimate manufacture of a cost-effective vaccine for global immunization. This proposed Cooperative Research Center (CRC) will critically evaluate a new means to biomanufacture HCV antigens known to induce specific immune responses to HCV - identified through human clinical studies, and predicted to be important in viral clearance - and evaluate responses to these antigens in appropriate in vitro and in vivo model systems. One of the co-Directors of this CRC has lead Chiron's discovery of recombinant antigens from HCV; the evaluation of his currently available suite of proteins in clinical trials indicates that a prophylactic and immunotherapeutic vaccine is feasible. Unfortunately, at least from the standpoint of manufacturing for public health markets, the optimal vaccine should consist of a "cocktail" of multiple antigens to elicit both antibody-mediated and T cell-mediated immune responses. The likely need for two separate protein expression systems to produce this vaccine, one limited by low yields, raises obstacles to commercial development - especially for global use. To overcome these production constraints, this CRC proposes to rapidly utilization current understanding of the properties of important vaccine components to develop and validate a new biomanufacturing system for multiple HCV antigens. A unique feature of this proposed CRC will be the use of green plants as versatile, highly cost-effective production system for recombinant proteins. The research proposed is an interactive partnership that draws upon Chiron's vaccine development expertise to critically evaluate HCV candidate vaccines produced by an academic team that has pioneered the use of plant biotechnology for subunit vaccine manufacture for more than a decade. PROJECT 1: Plant- Derived Envelope Glycoprotein E1/E2 Vaccine for HCV (Mason, H.) PROJECT 1 DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a major worldwide agent of acute and chronic hepatitis, with over 3% of the world's population infected and at risk for liver cirrhosis and cancer, and a US cost burden of $1 billion per year. Studies showed that vaccine development should target both antibody and T-cell mediated immunity. Recombinant envelope glycoproteins gpE1 and gpE2 are the leading vaccine candidates for antibody-mediated protection, showing protection in chimpanzee. However, gpE1/gpE2 is currently produced in cultured mammalian cells, with a limited capacity for scale-up to achieve global immunization. Alternatively, production of gpE1/gpE2 in plant systems has the potential for vast scale-up. We hypothesize that: 1) HCV gpE1/gpE2 vaccine can be produced in a plant system in a form that is equivalent to the mammalian cell product used for injection; 2) HCV gpE1/gpE2 vaccine can be scaled up to a commercially competitive level using a leaf or a grain seed-based expression system; and 3) Plant-derived HCV gpE1/gpE2 can stimulate antibody responses when orally delivered by ingestion of minimally processed plant tissue. The specific aims of this proposal will address these questions by using plant-optimized gpE1/gpE2 genes expressed in plants to assess the potential to assemble immunogenic gpE1/gpE2 heterodimers. We will examine tobacco leaf and corn seed expression systems and evaluate gpE1/gpE2 accumulation and quality to select the optimal system. M. Houghton at Chiron Corporation leads their HCV vaccine effort and will direct Project 3 of this HCV Research Center, which will purify gpE1/gpE2 from plant sources and test its immunogenic capacity in animal models. We will furthermore test the potential for use of orally delivered plant-derived gpE1/gpE2 vaccine, with the aim to develop a convenient and economical vaccine for the developing world. If successful, these studies will greatly enhance the capacity to produce an injectable vaccine for HCV, while also offering the possibility to improve worldwide immunization coverage with an oral vaccine.