Background The cell envelope of Staphylococcus aureus contains 2 major secondary cell wall glycopolymers: capsular polysaccharide (CP) and wall teichoic acid (WTA). Both CP and WTA are attached to the cell wall and play distinct roles in S. aureus colonization, pathogenesis, and bacterial evasion of host immune defenses. We aimed to investigate whether CP interferes with WTA-mediated properties. Methods Strains with natural heterogeneous expression of CP, strains with homogeneous high CP expression, and CP-deficient strains were compared regarding WTA-dependent phage binding, cell adhesion, IgG deposition, and virulence in vivo. Results WTA-mediated phage adsorption, specific antibody deposition, and cell adhesion were negatively correlated with CP expression. WTA, but not CP, enhanced the bacterial burden in a mouse abscess model, while CP overexpression resulted in intermediate virulence in vivo. Conclusions CP protects the bacteria from WTA-dependent opsonization and phage binding. This protection comes at the cost of diminished adhesion to host cells. The highly complex regulation and mostly heterogeneous expression of CP has probably evolved to ensure the survival and optimal physiological adaptation of the bacterial population as a whole.

中文翻译：

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金黄色葡萄球菌荚膜多糖阻碍壁磷壁酸功能

背景 金黄色葡萄球菌的细胞包膜含有 2 种主要的次生细胞壁糖聚合物：荚膜多糖 (CP) 和壁磷壁酸 (WTA)。 CP 和 WTA 均附着在细胞壁上，在金黄色葡萄球菌定植、发病机制和细菌逃避宿主免疫防御方面发挥着不同的作用。我们的目的是研究 CP 是否会干扰 WTA 介导的特性。方法比较具有 CP 天然异质表达的菌株、具有同质高 CP 表达的菌株和 CP 缺陷菌株的 WTA 依赖性噬菌体结合、细胞粘附、IgG 沉积和体内毒力。结果WTA介导的噬菌体吸附、特异性抗体沉积和细胞粘附与CP表达呈负相关。 WTA（而非 CP）增加了小鼠脓肿模型中的细菌负荷，而 CP 过度表达导致体内毒力中等。结论 CP 保护细菌免受 WTA 依赖性调理作用和噬菌体结合的影响。这种保护是以减少对宿主细胞的粘附为代价的。 CP 高度复杂的调控和大部分异质表达可能已经进化，以确保整个细菌群体的生存和最佳的生理适应。