Department of Microbiology and Immunology, University of British Columbia, Vancouver, V6T 1Z3 Canada.
J Bacteriol. 2010 Apr;192(8):2182-92. doi: 10.1128/JB.01222-09. Epub 2010 Feb 5.
Campylobacter jejuni is a highly prevalent human pathogen for which pathogenic and stress survival strategies remain relatively poorly understood. We previously found that a C. jejuni strain 81-176 mutant defective for key virulence and stress survival attributes was also hyper-biofilm and hyperreactive to the UV fluorescent dye calcofluor white (CFW). We hypothesized that screening for CFW hyperreactive mutants would identify additional genes required for C. jejuni pathogenesis properties. Surprisingly, two such mutants harbored lesions in lipooligosaccharide (LOS) genes (waaF and lgtF), indicating a complete loss of the LOS outer core region. We utilized this as an opportunity to explore the role of each LOS core-specific moiety in the pathogenesis and stress survival of this strain and thus also constructed DeltagalT and DeltacstII mutants with more minor LOS truncations. Interestingly, we found that mutants lacking the LOS outer core (DeltawaaF and DeltalgtF but not DeltagalT or DeltacstII mutants) exhibited enhanced biofilm formation. The presence of the complete outer core was also necessary for resistance to complement-mediated killing. In contrast, any LOS truncation, even that of the terminal sialic acid (DeltacstII), resulted in diminished resistance to polymyxin B. The cathelicidin LL-37 was found to be active against C. jejuni, with the LOS mutants exhibiting modest but tiled alterations in LL-37 sensitivity. The DeltawaaF mutant but not the other LOS mutant strains also exhibited a defect in intraepithelial cell survival, an aspect of C. jejuni pathogenesis that has only recently begun to be clarified. Finally, using a mouse competition model, we now provide the first direct evidence for the importance of the C. jejuni LOS in host colonization. Collectively, this study has uncovered novel roles for the C. jejuni LOS, highlights the dynamic nature of the C. jejuni cell envelope, and provides insight into the contribution of specific LOS core moieties to stress survival and pathogenesis.
空肠弯曲菌是一种高度流行的人类病原体，其致病和应激生存策略仍相对了解甚少。我们之前发现，一种关键毒力和应激生存特性缺失的空肠弯曲菌 81-176 突变体也具有超生物膜特性，并对紫外线荧光染料钙荧光白（CFW）高度反应。我们假设筛选 CFW 高反应突变体将鉴定空肠弯曲菌发病特性所需的其他基因。令人惊讶的是，两个这样的突变体在脂寡糖（LOS）基因（waaF 和 lgtF）中存在损伤，表明 LOS 外核心区域完全缺失。我们利用这一机会探索每个 LOS 核心特定部分在该菌株发病机制和应激生存中的作用，因此还构建了 LOS 截断程度较小的 DeltagalT 和 DeltacstII 突变体。有趣的是，我们发现缺乏 LOS 外核心的突变体（DeltawaaF 和 DeltalgtF，但不是 DeltagalT 或 DeltacstII 突变体）表现出增强的生物膜形成。完整的外核心的存在对于抵抗补体介导的杀伤也是必要的。相比之下，任何 LOS 截断，即使是末端唾液酸（DeltacstII），也会导致对多粘菌素 B 的抵抗力降低。发现抗菌肽 LL-37 对空肠弯曲菌有效，LOS 突变体对 LL-37 的敏感性略有但有差异。DeltawaaF 突变体而不是其他 LOS 突变菌株也表现出上皮细胞内生存能力缺陷，这是空肠弯曲菌发病机制中最近才开始阐明的一个方面。最后，使用小鼠竞争模型，我们现在提供了 LOS 在宿主定植中重要性的第一个直接证据。总的来说，这项研究揭示了空肠弯曲菌 LOS 的新作用，突出了空肠弯曲菌细胞包膜的动态性质，并深入了解了特定 LOS 核心部分对应激生存和发病机制的贡献。
