The development of probiotic yeast as an inexpensive vaccine delivery platform

描述(申请人提供)：胃肠道传染病是发展中国家婴儿死亡和发病的一个重要原因。全球有超过10亿人感染胃肠道蠕虫，腹泻病是导致5岁以下儿童死亡的第二大原因，每年约有200万儿童死亡。疫苗接种是最具成本效益的卫生干预措施之一，可以保护流行地区的人们免受感染，每年拯救数百万人的生命。尽管目前存在预防轮状病毒和霍乱感染的疫苗，但由于财政成本的原因，发展中国家对这些疫苗的接受程度很低。此外，迫切需要开发新的疫苗，提供对胃肠道其他疾病的保护。这项提议将开发一种新的负担得起的疫苗递送平台，使用益生菌酵母布氏酿酒酵母直接将疫苗递送到胃肠道。利用已经为酿酒酵母I建立的基因技术，将通过基因工程使布拉酵母表达诱导保护性免疫反应的抗原，并将其融合到一种新的佐剂技术--免疫体TM上。口服转基因的布氏链球菌将促进这些融合蛋白在粘膜表面的表达。基因转化的布氏沙门氏菌通过口服疫苗传递的抗原-免疫体TM融合蛋白将首先在小鼠身上证明产生免疫反应，并使用模型抗原描述不同给药方案产生的基线免疫反应。联合应用表达小鼠极化细胞因子的布氏链球菌将有助于武装Th1、Th2或Th17应答所驱动的不同免疫效应机制。这一点很重要，因为不同类型的病原体需要不同的免疫效应机制来清除。我还将通过分析小鼠对抗原攻击的记忆反应(浆母细胞和中央记忆T细胞)来检查该疫苗交付平台产生的免疫反应的寿命。产生的免疫反应的保护性将使用腹泻感染的小鼠模型微小隐孢子虫来证明。确定的针对微小隐孢子虫的疫苗靶点将由布氏葡萄球菌表达为免疫体TM融合蛋白，并用布氏酵母菌感染接种的小鼠。最后，我将产生布氏链球菌的营养缺陷型突变株，以促进这一疫苗输送平台在发展中国家的大规模生产，消除昂贵的抗生素选择的要求。该项目将从根本上改变发达国家和发展中国家接种疫苗的方式。

DESCRIPTION (provided by applicant): Infectious diseases of the gastrointestinal tract are a significant cause of infant mortality and morbidity in the developing world. Globally over 1 billio people are infected with gastrointestinal helminths and diarrheal disease is the second leading cause of death in children under 5, killing approximately 2 million children every year. Vaccination is one of the most cost-effective health interventions that can protect people from infection in endemic areas, saving millions of lives every year. Although vaccines currently exist to protect against infection with rotavirus and cholera, uptake of these vaccines in developing countries is poor due to the financial cost. Furthermore there is an urgent need for the development of new vaccines that provide protection against other diseases of the gastrointestinal tract. This proposal will develop a new affordable vaccine delivery platform that uses the probiotic yeast Saccharomyce cerevisiae boulardii to deliver vaccines directly to the gastrointestinal tract. Using genetic techniques already established for Saccharomyces cerevisiae I will genetically engineer S. boulardii to express antigens that induce protective immune responses fused to a novel adjuvant technology, ImmunobodiesTM. Oral administration of genetically transformed S. boulardii will facilitate expression of these fusion proteins in situat the mucosal surface. The generation of immune responses by antigen-ImmunobodyTM fusion proteins delivered by genetically transformed S. boulardii via oral vaccination will be initially demonstrated in mice using model antigen to describe the baseline immune responses generated by different dosing regimens. Co-administration of S. boulardii expressing mouse polarizing cytokines will facilitate the arming of different the immune effector mechanisms driven by Th1, Th2 or Th17 responses. This will be important because different types of pathogens require different immune effector mechanisms for clearance. I will also examine the longevity of the immune responses generated by this vaccine delivery platform by assaying for memory responses (plasmablasts and central memory T cells) in mice responding to antigen challenge. The protective nature of the immune responses generated will be demonstrated using a mouse model of diarrheal infection, Cryptosporidium parvum. Defined vaccine targets against C. parvum will be expressed by S. boulardii as ImmunobodyTM fusion proteins and the vaccinated mice challenged with Saccharomyce cerevisiae boulardii infection. Lastly I will generate auxotrophic mutants of S. boulardii to facilitate large-scale production of this vaccine delivery platform in developing countries removing the requirement for costly antibiotic selection. This project will radically change the way vaccines are administered both in developed and developing countries.