Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA.
Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA.
Carbohydr Res. 2019 Dec 1;486:107858. doi: 10.1016/j.carres.2019.107858. Epub 2019 Oct 26.
A hypervirulent A. hydrophila (vAh) pathotype has been identified as the etiologic agent responsible for disease outbreaks in farmed carp species and channel catfish (Ictalurus punctatus) in China and the Southeastern United States, respectively. The possible route of infection has previously been unknown; however, virulence is believed to be multifactorial, involving the production/secretion of several virulence factors, including a high molecular weight group 4 capsular polysaccharide. Here we present chemical structural evidence of a novel capsule- and LPS-associated O-antigen found present in vAh isolated during these disease outbreaks. In this study, the chemical structure of the vAh O-antigen was determined by chemical analysis, Smith degradation, mass spectrometry, and 2D proton and carbon nuclear magnetic resonance (NMR) spectroscopy and found to be unique among described bacterial O-antigens. The O-antigen consists of hexasaccharide repeating units featuring a 4)-α-l-Fucp-(1-3)-β-d-GlcpNAc-(1-4)-α-l-Fucp-(1-4)-β-d-Glcp-(1- backbone, substituted with single residue side chains of α-d-Glcp and α-d-Quip3NAc linked to O-3 of the two fucose residues. The polysaccharide is partially O-acetylated on O-6 of the 4-substituted β-Glcp residue.
一种高毒力的嗜水气单胞菌（vAh）血清型已被确定为分别在中国养殖鲤鱼和美国东南部养殖斑点叉尾鮰疾病爆发的病原体。以前未知可能的感染途径；然而，毒力被认为是多因素的，涉及多种毒力因子的产生/分泌，包括高分子量组 4 荚膜多糖。在这里，我们提出了在这些疾病爆发期间分离的 vAh 中存在的新型囊泡和 LPS 相关 O-抗原的化学结构证据。在这项研究中，通过化学分析、Smith 降解、质谱和二维质子和碳核磁共振（NMR）光谱确定了 vAh O-抗原的化学结构，发现其在描述的细菌 O-抗原中是独特的。O-抗原由六糖重复单元组成，具有 4）-α-l-Fucp-（1-3）-β-d-GlcpNAc-（1-4）-α-l-Fucp-（1-4）-β-d-Glcp-（1- 骨架，由与两个呋喃糖残基的 O-3 连接的α-d-Glcp 和α-d-Quip3NAc 的单残基侧链取代。多糖部分在 4 位取代的β-Glcp 残基的 O-6 上被 O-乙酰化。
