肺炎链球菌荚膜多糖结构与合成的研究进展

Advances in the chemical structures and biosynthesis of capsular polysaccharides of Streptococcus pneumoniae

摘要:

肺炎链球菌(Streptococcus pneumoniae)是一种能够引发人类肺炎和脑膜炎等严重疾病的病原体。其中，包裹着细菌的荚膜多糖(capsular polysaccharide, CPS)是关键的致病因子和重要抗原，已被制成多糖疫苗和多糖蛋白结合疫苗，在抗细菌感染中发挥了巨大作用。荚膜多糖由寡糖单位重复聚合而成，每个寡糖单位通常含有2−8个单糖残基，其结构复杂，具有不同的抗原表位。荚膜多糖也是细菌分型的依据，目前已发现肺炎链球菌有107种血清型，每种血清型都有特定的荚膜多糖结构、遗传基础和血清学特征。荚膜多糖结构的多样性和不断变化是肺炎链球菌难以被根除的主要原因。本文总结了目前已知的95个肺炎链球菌荚膜多糖的化学结构，探讨了荚膜多糖的遗传基础、合成机制和纯化方法，旨在提高对荚膜多糖结构的全面认知，为深入研究荚膜多糖的功能和进化机制以及多糖疫苗的制备提供参考。

Abstract:

Streptococcus pneumoniae causes serious diseases such as pneumoniae and meningitis in humans. Capsular polysaccharides (CPSs) surrounding bacteria are not only key virulence factors but also major antigens. Therefore, CPSs have been prepared into polysaccharide vaccines and polysaccharide conjugate vaccines, which have greatly reduced the infection of pneumococci. CPSs are formed by polymerization of oligosaccharide repeating units which generally have 2−8 monosaccharides. CPSs present complex structures with diverse antigenic epitopes, being the basis of bacterial serotyping. Currently, 107 serotypes of S. pneumoniae have been identified. Each serotype has a unique CPS structure, a stable genetic basis, and specific serological characteristics. The diversity and constant changes of CPS structures explain the difficulty in the eradication of pneumococci. This review summarizes the known chemical structures of 95 CPSs and discusses the genetic basis, biosynthesis mechanism, and purification methods of CPSs. This review aims to enrich the knowledge about CPS diversity and provide a reference for probing into the functions and evolution of CPSs as well as for preparing polysaccharide vaccines.