Mucosal live vector vaccine against recurrent Clostridium difficile infections

描述（由申请方提供）：细菌活载体疫苗代表了一种具有特殊灵活性的疫苗开发策略。在这种方法中，编码不相关的细菌、病毒或寄生虫病原体的外源抗原的基因在减毒细菌疫苗株中表达，所述减毒细菌疫苗株将这些外源抗原递送至免疫系统，从而引发相关的免疫应答。减毒伤寒沙门氏菌活载体疫苗的研制已取得重大进展。在遗传稳定的表达质粒、提高外源抗原特异性免疫的抗原输出系统以及在小鼠和非人灵长类动物中建立鼻内模型以表征对这些活载体的粘膜、体液和细胞免疫应答方面取得了进展。对于未来的临床试验至关重要的是，非抗生素质粒选择系统最近已经被改造以提高这些疫苗的安全性。本研究计划的广泛假设是，通过适当操作伤寒沙门氏菌活载体平台技术，我们可以构建一种粘膜给药的多价疫苗，以免疫复发性艰难梭菌感染（RCDI）。为了实现这一点，我们将在一个单一的菌株中同时设计基于非抗生素质粒的和新的染色体表达系统，以共同表达三个C.艰难梭菌毒素;肠毒素A和B以及二元毒素。该活载体菌株的免疫原性将使用免疫原性的鼠鼻内模型和基于异源初免/加强方法的疫苗接种策略来确定，其中宿主用C.使用活载体和作为纯化蛋白递送的艰难梭菌抗原。有希望的候选人引发针对所有三种C.将进一步测试艰难梭菌抗原在小鼠中的保护作用，所述小鼠类似地用多价菌株免疫并用来自流行性梭菌菌株的孢子口胃攻击。很难

DESCRIPTION (provided by applicant): Bacterial live vector vaccines represent a vaccine development strategy that offers exceptional flexibility. In this approach, genes that encode foreign antigens of unrelated bacterial, viral or parasitic pathogens are expressed in an attenuated bacterial vaccine strain that delivers these foreign antigens to the immune system, thereby eliciting relevant immune responses. Significant progress has been made in the development of attenuated Salmonella enterica serovar Typhi live vector vaccines. Advances have been made in genetically stabilized expression plasmids, antigen export systems to improve foreign antigen-specific immunity, and the establishment of intranasal models in both mice and non-human primates for characterizing mucosal, humoral, and cellular immune responses to these live vectors. Of critical importance to future clinical trials, non-antibiotic plasmid selection systems have recently been engineered to improve the safety of these vaccines. The broad hypothesis of this research plan is that by appropriate manipulation of the Salmonella enterica serovar Typhi live vector platform technologies, we can construct a mucosally administered multivalent vaccine to immunize against recurrent Clostridium difficile infections (RCDI). To accomplish this, we will engineer within a single strain both non-antibiotic plasmid-based and novel chromosomal expression systems to express in concert the non-toxic cell-binding domains of three C. difficile toxins; enterotoxins A and B and binary toxin. The immunogenicity of this live vector strain will be determined using a murine intranasal model of immunogenicity, and a vaccination strategy based on a heterologous prime/boost approach in which the host is immunized sequentially with C. difficile antigens delivered both using live vectors and as purified proteins. Promising candidates eliciting antibody responses against all three C. difficile antigens will be further tested for protection in mice similarly immunized with he multivalent strain and challenged orogastrically with spores from an epidemic strain of C. difficile.