Vi antigen is the capsular polysaccharide of Salmonella typhi, which can cause typhoid fever. With the increasing threat of antiboitic resistance, vaccination against Salmonella typhi is a preferred way to prevent this disease. Chemical synthesis of fragments of Vi antigen is in urgent need for the development of structure-homogeneous and quality-controlled oligosaccharide vaccines. However, it is extremely challenging to synthesize large oligosaccharide fragments of Vi antigen owing to the exclusive α-1,4-linkage of polyaminogalacturonates. Herein, a series of Vi oligosaccharides ranging from pentamer to octamer were efficiently prepared using 2,3-N,O-oxazolidinone protected glycosides as building blocks based on the preactivation protocol. The heptasaccharide and octasaccharide fragments were synthesized for the first time. The competitive ELISA evaluation suggested that the hexasaccharide might be the minimum epitope of Vi antigen, which provides a significant guidance for the future development of Vi oligosaccharide vaccines.

中文翻译：

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化学合成和五的生物学评价，从八-糖类片段Vi的多糖伤寒沙门氏菌†

Vi抗原是伤寒沙门氏菌的荚膜多糖，可引起伤寒。随着抗药性威胁的增加，针对伤寒沙门氏菌的疫苗接种是预防这种疾病的首选方法。迫切需要Vi抗原片段的化学合成，以开发结构均质且质量控制的寡糖疫苗。然而，由于聚氨基半乳糖醛酸酯的排他性α-1,4-键，合成Vi抗原的大寡糖片段极具挑战性。在此，使用2,3- N，O有效地制备了从五聚体到八聚体的一系列Vi低聚糖。-恶唑烷酮基于预活化方案将糖苷作为构建基保护。首次合成了七糖和八糖片段。竞争性ELISA评估表明，六糖可能是Vi抗原的最小表位，这为Vi寡糖疫苗的未来开发提供了重要指导。