Multi-componet Vaccine for Staphylcoccus epidermidis

说明(申请人提供)：凝固酶阴性葡萄球菌(CONS)，特别是表皮葡萄球菌，是医院获得性感染的主要原因，由于生物被膜形成和抗生素耐药性，治疗可能很困难。这种形成多层生物膜的能力在一定程度上取决于被称为聚N-乙酰-氨基葡萄糖(PNAG)的表面多糖的产生。以往的工作已经证明，PNAG是一种体内表达的抗原，是表皮葡萄球菌和金黄色葡萄球菌保护性免疫的靶标。然而，PNAG的产生在CONS的临床分离株中差异很大，潜在地限制了这种表面聚合物作为对抗葡萄球菌菌株的疫苗的唯一成分的使用。因此，需要对其他潜在的候选疫苗进行调查。表皮葡萄球菌和其他相关的CON阐述了作为胞外聚合物，聚-DL-谷氨酸(DL-PGA)促进人类宿主的生长和生存。这些聚合物也是由芽孢杆菌产生的，包括地衣芽孢杆菌和更明显的炭疽杆菌，PGA抗体介导对炭疽的保护性免疫。初步工作表明，地衣芽孢杆菌DL-PGA结合疫苗的小鼠抗体可以在体外吞噬细胞实验中介导人多形核白细胞和补体对各种表皮葡萄球菌菌株的杀伤作用。此外，吞噬细胞的杀伤不依赖于PNAG的产生，因为PNAG阳性和阴性的临床分离株都被同样的调理和杀死。正在评估的主要假设是，针对表皮葡萄球菌的优化疫苗应该是多组分的，并包括PNAG和D-和/或L-谷氨酸的组合，以便最大限度地覆盖对葡萄球菌临床分离株的覆盖和/或从单个组分获得协同效应。将合成多种候选疫苗，包括高分子量D-和L-PGA，D或L构型的20聚体合成PGA多肽，以及与载体蛋白破伤风类毒素结合的dPNAG。体外吞噬细胞实验将被用作潜在保护性抗体的第一个筛查。在小鼠导管感染模型中，将通过被动和主动免疫对抗多株CONS的攻击，进一步测试诱导它们的高度光学抗体和疫苗的免疫保护效果。通过这些研究获得的见解将有助于我们评估控制和预防CONS感染的免疫治疗策略。项目简介：在过去的20年里，表皮葡萄球菌已经成为医院感染中最常见的病原体之一。重要的是，许多表皮葡萄球菌菌株对常用抗生素具有抗药性，这突显了寻找新的感染预防和治疗方法的必要性，例如为疫苗开发确定新的分子靶点。本申请建议研究两种不同的表皮葡萄球菌表面聚合物，称为聚-DL-谷氨酸和去乙酰化聚-N-乙酰-氨基葡萄糖(DPNAG)，单独或联合作为针对这种病原体的新型疫苗的组成部分的疫苗潜力。

DESCRIPTION (provided by applicant): Coagulase-negative staphylococci (CoNS), notably Staphylococcus epidermidis, are a predominant cause of hospital-acquired infections and treatment can be difficult owing to biofilm formation and antibiotic resistance. This ability to form a multi-layered biofilm depends, in part, on the production of the surface polysaccharide termed poly-N-acetyl-glucosamine (PNAG). Previous work has demonstrated that PNAG is an in vivo expressed antigen and the target for protective immunity for both S. epidermidis and Staphylococcus aureus. However, production of PNAG varies widely among clinical isolates of CoNS, potentially limiting the use for this surface polymer as the sole component of a vaccine against staphylococcal strains. Therefore, additional potential vaccine candidates need to be investigated. S. epidermidis and other related CoNS elaborate, as extracellular polymers, poly-?-DL-glutamic acid (DL-PGA) to facilitate growth and survival in the human host. These polymers are also produced by Bacillus spp., including B. licheniformis and more notably B. anthracis, and antibody to the PGA mediates protective immunity to anthrax. Preliminary work has shown that mouse antibodies raised to a B. licheniformis DL-PGA-conjugate vaccine can mediate killing of various S. epidermidis strains by human polymorphonuclear leukocytes and complement in an in vitro opsonophagocytic assay. Moreover, the opsonophagocytic killing was independent of PNAG production, as both PNAG positive and negative clinical isolates were similarly opsonized and killed. The major hypothesis being evaluated is that an optimized vaccine that would target S. epidermidis should be multi-component and include PNAG and D- and/or L-glutamic acid in combination in order to provide maximum coverage against staphylococcal clinical isolates and/or obtain a synergistic effect from the individual components. Multiple vaccines candidates will be synthesized including high molecular weight D- and L-PGA, 20-mer synthetic PGA peptides of either the D or L configuration and dPNAG conjugated to the carrier protein tetanus toxoid. The in vitro opsonophagocytic assay will be used as the first screen for potentially protective antibodies. Highly opsonic antibodies and vaccines that elicit them will be further tested for their immunoprotective efficacy by passive and active immunization against challenge with multiple strains of CoNS in a murine catheter-infection model. Insights gained by these studies will help us to evaluate immunotherapeutic strategies for control and prevention of infection by CoNS. Project Narrative: Over the past 2 decades, Staphylococcus epidermidis has become one of the most prevalent pathogens involved in hospital-acquired infections. Importantly many strains of S. epidermidis are resistant to commonly used antibiotics, underscoring the need to find new approaches to prevention and treatment of infection such as identifying novel molecular targets for vaccine development. This application proposes to investigate the vaccine potential of two different S. epidermidis surface polymers termed poly-DL-glutamic acid and deacetylated poly-N-acetyl-glucosamine (dPNAG) either alone or in combination as components of a novel vaccine against this pathogen.