Remodeling Salmonella outer membrane for vaccine development

描述（由申请人提供）：减毒沙门氏菌活疫苗能够诱导对其他肠道病原体产生交叉反应的抗体，特别是在经过工程设计以实现体内o抗原合成下调的菌株中。如果沙门氏菌脂多糖（LPS）进一步被截断，这可能会导致更有效地向宿主免疫系统呈递保守的外膜蛋白（OMPs），这将导致免疫反应，对许多其他沙门氏菌和其他革兰氏阴性肠道病原体具有交叉保护作用。此外，暴露于相当保守的核心寡糖和增强外膜囊泡的产生也可能有助于产生交叉保护免疫反应。在本提案中，我们将构建一系列突变来实现受调节的o抗原或核心合成，使全长LPS在免疫时存在，但在宿主定植后丢失。我们还将包括上调指定必需离子摄取蛋白的基因表达的突变，包括铁调节外膜蛋白（IROMPs）。候选疫苗菌株将通过引入其他突变来进一步修饰，包括pagC和ompX基因，这些基因在体内被最大限度地上调以促进外膜囊泡的产生，从而最大限度地诱导与其他肠道病原体OMPS交叉反应的抗体。该项目的成功将为人类提供具有广谱保护作用的高效RASV。

DESCRIPTION (provided by applicant): Attenuated live Salmonella vaccines have ability to induce antibodies cross-reactive to other enteric pathogens, particularly in strains engineered to achieve down-regulation of O-antigen synthesis in vivo. It is possible that if the Salmonella lipopolysaccharide (LPS) is truncated further, this may result in more effective presentation of conserved outer membrane proteins (OMPs) to the host immune system, which will lead to an immune response that is cross protective against a number of other Salmonella species and to other Gram- negative enteric pathogens. In addition, exposure of the fairly conserved core oligosaccharide and enhanced production of outer membrane vesicles may also aid in production of a cross-protective immune response. In this proposal, we will construct a series of mutations to achieve regulated O-antigen or core synthesis such that full length LPS is present at the time of immunization but is lost after colonization of the host. We will also include mutations that up-regulate expression of genes that specify essential ion uptake proteins including the iron regulated outer membrane proteins (IROMPs). Candidate vaccine strains will be further modified by introduction of other mutations including the pagC and ompX genes that are maximally up-regulated in vivo to promote outer membrane vesicles production to maximally induce antibodies cross-reactive to the OMPS of other enteric pathogens. The success of this project could lead to efficacious RASV with broad spectrum protection against enteric bacteria for human use. PUBLIC HEALTH RELEVANCE: Effective live bacterial vaccines hold the promise of providing low cost, orally administered, life-long protection against enteric bacteria. The goal of this project is to construct novel Salmonella vaccines to maximally expose conserved outer membrane proteins to the immune system to induce the higher cross-reactive antibodies to enteric bacteria via shutting off core oligosaccharide synthesis in vivo but retaining intact the LPS in vitro to facilitate invasion.