SYNTHETIC VACCINE AGAINST SHIGELLOSIS I--SHIGELLA DYSENTERIAE TYPE 1

志贺氏菌病是一种世界性的主要肠道疾病，可引起腹泻和 痢疾是一种急性侵袭性下肠道疾病，在许多 世界上感染剂量非常低的部分地区(约100 细菌)。由于许多菌株对多重抗生素产生耐药性 志贺氏菌病的治疗是困难的，通过 接种疫苗应该是控制这种疾病的替代方案。我们 假设O-特异性多糖的延伸片段 志贺氏菌脂多糖的(O-SP)组分可能是合适的 用于在共价偶联时诱导保护性抗体 免疫原性蛋白。使用已定义的合成糖 用结构代替高度复杂结构的多糖 提供了许多优点，包括增强的偶联物的一致性， 将糖类与预先确定的末端结合在一起 糖链，消除了许多分析困难 与多糖蛋白疫苗相关。此外， 生物来源的材料可能固有的危险也是 最小化。基于这一假设，我们正在开发合成的 基于低聚糖的明确分子免疫原 特点。我们设计了一个综合策略来准备 1型痢疾链霉菌O-SP的寡糖片段 由四糖重复单元组成，四糖重复单元由 D-半乳糖、N-乙酰-D-氨基葡萄糖和L-鼠李糖。从 携带正交保护基团和活化基的单糖， 组装了四糖供体/受体分子。迭代 提供二聚体、三聚体和四聚体的构件组合 对应于八、十二和的重复单元 原生O-SP的十六糖部分。这些 低聚/多糖中含有w-肼甲酰戊基 糖苷元，可用于将糖固定在蛋白质和其他 大分子。开发了一种新的异双功能连接物分子 并用于在温和的条件下将糖连接到蛋白质上。

Shigellosis is a major enteric disease worldwide causing diarrhea and dysentery, an acute invasive disease of the lower intestines in many parts of the world with a very low infectious dose (approximately 100 bacteria). Because of the multiple-antibiotic resistance of many strains of Shigellae, the treatment of shigellosis is difficult and prevention by vaccination should be an alternative to control this disease. We hypothesized that extended fragments of the O-specific polysaccharide (O-SP) components of the lipopolysaccharides of Shigellae may be suitable for the induction of protective antibodies when covalently coupled to immunogenic proteins. The use of synthetic saccharides of defined structure instead of polysaccharides of highly complex architecture offers numerous advantages including enhanced uniformity of conjugates, the possibility of using saccharides with pre-determined termini on the saccharide chain, and elimination of much of the analytical difficulties associated with the polysaccharide-protein vaccines. In addition, the possible dangers inherent with materials of biological origin are also minimized. Based on this hypothesis we are developing synthetic oligosaccharide-based immunogens of well-defined molecular characteristics. We designed a synthetic strategy to prepare oligosaccharide fragments of the O-SP of S. dysenteriae type 1. The O-SP consists of a tetrasaccharide repeating unit that is composed of D-galactose, N-acetyl-D-glucosamine, and L-rhamnose. Starting from monosaccharides that carry orthogonal protecting and activating groups, a tetrasaccharide donor/acceptor molecule was assembled. Iterative combination of the building blocks afforded di-, tri- and tetramers of the repeating unit corresponding to octa-, dodeca- and hexadeca-saccharide portions of the native O-SP. These oligo/polysaccharides are equipped with an w-hydrazinocarbonylpentyl aglycon that can be used to anchor the saccharides to proteins and other macromolecules. A new heterobifunctional linker molecule was developed and used to attach the saccharides to proteins under mild conditions.