Genetically Engineered Oral Vaccines and Caries Immunity

描述(由申请人提供)：重组无毒沙门氏菌疫苗正在研究其表达异种病原体毒力抗原克隆基因的能力，以及它们在开发预防包括龋齿在内的各种传染病的粘膜疫苗方面的潜在应用。然而，这些安全的活载体疫苗介导宿主反应的机制(S)仍然知之甚少。模式识别受体(PRRs)，包括Toll样受体(TLRs)，表达在宿主细胞上/在宿主细胞中，识别与微生物成分相关的不同分子模式。树突状细胞表面TLRs对微生物成分的识别导致先天免疫反应的诱导和获得性免疫的激活。我们用表达变形链球菌黏附agI/II的唾液结合区(SBR)基因的沙门氏菌载体疫苗免疫研究的发现表明，共刺激分子CD80和CD86在介导粘膜和系统抗体反应中发挥着不同的和多余的作用，从而提供了证据，表明载体和SBR可能通过TLRs以不同的方式向天然免疫系统发出信号。其他证据表明，不止一个TLR可能参与调节和增强沙门氏菌载体产生的对SBR的免疫反应。我们提出的研究的基本假设是，暴露于沙门氏菌载体疫苗后的各种宿主细胞上TLRs之间的相互作用将影响对沙门氏菌表达的克隆抗原的适应性免疫反应的结果。我们的研究将集中于确定TLRs在表达变形链球菌克隆毒力抗原的复合沙门氏菌载体疫苗黏膜免疫后介导适应性免疫反应的调节作用。其具体目的是：1)确定TLRs以及TLRs之间的相互作用，TLRs参与选择性增强对沙门氏菌载体疫苗表达的变形链球菌克隆抗原的粘膜和全身反应；2)确定TLRs在T细胞和B细胞对沙门氏菌载体疫苗表达的克隆抗原的适应性免疫反应中的作用。使用TLR基因敲除小鼠的体内免疫反应和过继转移模型以及体外检测系统将用于解决这些目标。了解每一个TLR以及TLR之间的相互作用，以及树突状细胞、T细胞和B细胞中TLR信号对特定微生物抗原的适应性反应的贡献，将有助于设计改进的沙门氏菌载体疫苗和免疫方案，以诱导针对包括龋齿在内的传染病的保护性免疫反应。 公共卫生相关性：正在开发重组减毒沙门氏菌疫苗，并测试其在诱导对各种感染源(包括龋齿和牙周病的病原体)的保护性粘膜和系统免疫反应方面的有效性。与含有纯化微生物成分的疫苗相比，活载体疫苗在诱导黏膜对微生物病原体的免疫反应方面更有效，生产也更经济。因此，确定沙门氏菌载体疫苗微生物成分的宿主识别机制是至关重要的，这些微生物成分调节对表达异源病原体(如变形链球菌)克隆毒力抗原的免疫反应的性质，以开发高效增强对黏膜病原体(包括与口腔相关的病原体)的保护性免疫反应的重组无毒沙门氏菌疫苗。

DESCRIPTION (provided by applicant): Recombinant avirulent Salmonella vaccines are being studied for their ability to express cloned genes of virulence antigens of heterologous pathogens, and for their potential use in the development of mucosal vaccines protective against various infectious diseases including dental caries. However, the mechanism(s) by which these safe, live vector vaccines mediate host responses are still poorly understood. Pattern-recognition receptors (PRRs), including the Toll-like receptors (TLRs), are expressed on/in host cells and recognize distinct molecular patterns associated with microbial components. The recognition of microbial components by TLRs on dendritic cells leads to the induction of an innate immune response and the activation of adaptive immunity. Our findings from immunization studies with a Salmonella vector vaccine expressing the gene encoding the saliva-binding region (SBR) of the adhesion AgI/II of Streptococcus mutans showed that the costimulatory molecules CD80 and CD86 play distinct, as well as redundant roles in mediating mucosal and systemic antibody responses, thus providing evidence that the vector and SBR may be signaling the innate immune system differently, presumably via TLRs. Other evidence suggests that more than one TLR may be involved in mediating and potentiating the immune response to SBR produced by the Salmonella vector. The fundamental hypothesis of our proposed studies is that the interplay between TLRs on various host cells that are engaged following exposure to the Salmonella vector vaccine will influence the outcome of the adaptive immune response to the cloned antigen expressed by the Salmonella. Our studies will focus on defining the regulatory roles of TLRs that mediate the adaptive immune response following mucosal immunization with a complex Salmonella vector vaccine expressing a cloned virulence antigen of S. mutans. The specific aims are; 1) to define the TLRs and the interplay between the TLRs involved in a selective augmentation of mucosal and systemic responses to the cloned antigen of S. mutans expressed by a Salmonella vector vaccine and 2) to determine the role of TLRs on T cells and B cells for an adaptive immune response to a cloned antigen expressed by a Salmonella vector vaccine. In vivo immune response and adoptive transfer models that use TLR knockout mice, as well as in vitro assay systems will be used to address the aims. An understanding of each TLR and the interplay between TLRs involved in mediating the innate and adaptive host responses to a vaccine candidate, and the contribution of TLR signaling in dendritic, T and B cells for the resulting adaptive response to specific microbial antigens will help in the design of improved Salmonella vector vaccines and immunization regimens for the induction of protective immune responses against infectious diseases, including dental caries. PUBLIC HEALTH RELEVANCE: Recombinant attenuated Salmonella vaccines are being developed and tested for their effectiveness in inducing protective mucosal and systemic immune responses to a variety of infectious agents, including the etiologic agents of dental caries and periodontal disease. Live vector vaccines are more effective in inducing mucosal immune responses against microbial pathogens and more economical to produce than vaccines consisting of purified microbial components. Therefore, it is critical to determine the mechanisms involved in host recognition of microbial components of a Salmonella vector vaccine that regulate the nature of the immune response induced to the expressing cloned virulence antigen of a heterologous pathogen, such as mutans streptococci, in order to develop recombinant avirulent Salmonella vaccines that are highly effective in potentiating protective immune responses against mucosal pathogens, including those associated with the oral cavity.