Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris, France; Unité 1202, INSERM, U1202, 75015 Paris, France.
Institut Pasteur, Unité de Pathogénie Microbienne Moléculaire, 75724 Paris, France; Unité 1202, INSERM, U1202, 75015 Paris, France; Institut Gustave Roussy, Laboratoire de Thérapie Cellulaire, 94800 Villejuif, France.
Cell Host Microbe. 2017 Jun 14;21(6):769-776.e3. doi: 10.1016/j.chom.2017.05.004.
Shigella is a leading cause of dysentery worldwide, with the majority of infections caused by two subgroups, S. flexneri and S. sonnei. Although S. flexneri has been highly prevalent in low-income countries, global development has brought an increase in S. sonnei at the expense of S. flexneri. However, the mechanisms behind this shift are not understood. Here we report that S. sonnei, but not S. flexneri, encodes a type VI secretion system (T6SS) that provides a competitive advantage in the gut. S. sonnei competes against E. coli and S. flexneri in mixed cultures, but this advantage is reduced in T6SS mutant strains. In addition, S. sonnei can persist as well as outcompete E. coli and S. flexneri in mice in a T6SS-dependent manner. These findings suggest that S. sonnei has a competitive advantage over S. flexneri and potentially explain the increasing global prevalence of S. sonnei.
志贺氏菌是世界范围内痢疾的主要致病菌，其中大多数感染由两个亚群引起，即 S. flexneri 和 S. sonnei。尽管 S. flexneri 在低收入国家高度流行，但全球发展带来了 S. sonnei 的增加，而 S. flexneri 的数量则相应减少。然而，这种转变的机制尚不清楚。在这里，我们报告 S. sonnei 而非 S. flexneri 编码一种类型 VI 分泌系统（T6SS），该系统在肠道中提供竞争优势。S. sonnei 在混合培养物中与 E. coli 和 S. flexneri 竞争，但在 T6SS 突变株中这种优势会降低。此外，S. sonnei 可以以 T6SS 依赖的方式在小鼠中与 E. coli 和 S. flexneri 一样持久存在并具有竞争优势。这些发现表明 S. sonnei 比 S. flexneri 具有竞争优势，可能解释了 S. sonnei 在全球范围内流行度增加的原因。
