Transgenic Plant-Derived CMV Glycoprotein B Vaccine

描述（由申请人提供）：近年来推广的一种创新疫苗策略是口服免疫的概念，使用转基因植物作为疫苗。转基因植物疫苗的理由是基于这种疫苗大规模生产的潜力；降低费用;改善粘膜免疫反应；以及管理的便利性。虽然这类疫苗在动物模型和人体试验中显示具有免疫原性，但关于这种免疫策略的保护功效的数据很少。同样，与口服由更传统的表达系统产生的重组蛋白相比，口服转基因植物材料的相对免疫原性和功效的信息也很少。由于抗原稳定性（由植物细胞井的存在所赋予）和肠道免疫处理的感知差异，假设植物疫苗优于口服给药。本研究建议在保护性免疫原明确的动物系统中验证这一假设。所研究的系统为豚鼠巨细胞病毒（GPCMV）模型，蛋白为糖蛋白B （gB）蛋白。选择这种蛋白质的理由是，这种蛋白质在疫苗介导的对巨细胞病毒疾病的保护中明显有效，从而为测试口服疫苗接种的“概念证明”提供了宝贵的机会。在这个模型中，我们已经证明，当在杆状病毒中以佐剂亚单位疫苗的形式表达gB蛋白时，对母体-胎盘-胎儿单位的保护起着至关重要的作用。此外，由于巨细胞病毒感染通常在粘膜表面获得，因此评估重组gB疫苗在粘膜部位口服疫苗的效果值得调查。利用农杆菌介导的重组转基因植物表达系统，我们设计了一株转基因GPCMV gB的拟南芥植物，该植物将用于口服佐剂（霍乱毒素B）免疫豚鼠，然后在怀孕期间进行GPCMV攻击。也将使用杆状病毒纯化的gB进行口服疫苗接种。我们将验证植物源性疫苗在口服途径下比杆状病毒源性蛋白质疫苗更具免疫原性和保护性的假设。评价该疫苗的免疫原性及对先天性感染和疾病的保护作用。这些研究将推进HCMV疫苗领域，这是一项重要的公共卫生重点。此外，这些研究将提供有关口服转基因植物疫苗潜在功效的数据，这一概念受到相对较少的功效分析。基于gB是豚鼠巨细胞病毒模型中的关键免疫原这一基本原理，与通过其他方法纯化的蛋白进行口服免疫相比，有一个令人信服的理由来评估该蛋白作为口服植物基疫苗。这些研究将推动植物和巨细胞病毒疫苗领域的发展。

DESCRIPTION (provided by applicant): An innovative vaccine strategy that has been promoted in recent years is the concept of oral immunization, using transgenic plants as vaccines. The rationale for transgenic plant vaccines is based on the potential for mass productive of such vaccines; lower expense; improved mucosal immune responses; and ease of administration. Although such vaccines have been shown in animal models and in human trials to be immunogenic, there is very little data about the protective efficacy of this immunization strategy. There is similarly little information about the relative immunogenicity and efficacy of following oral administration of transgenic plant material compared with oral administration of recombinant proteins generated by more traditional expression systems. Because of perceived differences in antigen stability (conferred by the presence of a plant cell well) and immunologic processing in the gut, plant vaccines are hypothesized to be superior for oral administration. This study proposes to test this hypothesis in an animal system in which the protective immunogen is well defined. The system to be studied is the guinea pig cytomegalovirus (GPCMV) model, and the protein is the glycoprotein B (gB) protein. The rationale for choosing this protein is that this protein is clearly effective in vaccine-mediated protection against CMV disease, thus providing a valuable opportunity for testing "proof of concept" of oral vaccination. In this model, we have shown that humoral responses generated against the gB protein, when expressed as an adjuvanted subunit vaccine in baculovirus, are critical in protection of the maternal-placental-fetal unit. Furthermore, since CMV infections are typically acquired at mucosal surfaces, evaluation of recombinant gB vaccine administered at an oral vaccine, at a mucosal site, warrants investigation. Using Agrobacteria tumefaciens-mediated recombination in transgenic plant expression systems, we have engineered an Arabidopsis plant transgenic for GPCMV gB, which will be utilized to immunize guinea pigs, orally, with adjuvant (cholera toxin B), followed by GPCMV challenge during pregnancy. Oral vaccination will also be conducted with baculovirus-purified gB. We will test the hypothesis that plant-derived vaccine is more immunogenic and protective than baculovirus-derived protein when administered by an oral route. The immunogenicity and protective efficacy against congenital infection and disease of this vaccine will be evaluated. These studies will advance the field of HCMV vaccines, an important public health priority. Moreover, these studies will provide data regarding the potential efficacy of oral transgenic plant vaccination, a concept which has been subjected to relatively few efficacy analyses. Based on the rationale that gB is a key immunogen in the CMV model in guinea pigs, there is a compelling rationale to evaluate this protein as an oral plant-based vaccine, compared to oral immunization with proteins purified by other approaches. These studies will advance the fields of plant and CMV vaccines.