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首页> 外文期刊>Infection and immunity >Role of RpoS in Fine-Tuning the Synthesis of Vi Capsular Polysaccharide in Salmonella enterica Serotype Typhi
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Role of RpoS in Fine-Tuning the Synthesis of Vi Capsular Polysaccharide in Salmonella enterica Serotype Typhi

机译：RpoS在微调肠炎沙门氏菌血清型鼠伤寒中荚膜多糖合成中的作用

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Regulation of the synthesis of Vi polysaccharide, a major virulence determinant in Salmonella enterica serotype Typhi, is under the control of two regulatory systems, ompR-envZ and rscB-rscC, which respond to changes in osmolarity. Some serotype Typhi strains exhibit overexpression of Vi polysaccharide, which masks clinical detection of lipopolysaccharide O antigen. This variation in Vi polysaccharide and O antigen display (VW variation) has been observed since the initial studies of serotype Typhi. In this study, we report that rpoS plays a role in this increased expression in Vi polysaccharide. We constructed a variety of isogenic serotype Typhi mutants that differed in their expression levels of RpoS and examined the role of the rpoS product in synthesis of Vi polysaccharide under different osmolarity conditions. Vi polysaccharide synthesis was also examined in serotype Typhi mutants in which the native promoter of the rpoS was replaced by an araCPBAD cassette, so that the expression of rpoS was arabinose dependent. The RpoS? strains showed increased syntheses of Vi polysaccharide, which at low and medium osmolarities masked O antigen detection. In contrast, RpoS+ strains showed lower syntheses of Vi polysaccharide, and an increased detection of O antigen was observed. During exponential growth, when rpoS is unstable or present at low levels, serotype Typhi RpoS+ strains overexpress the Vi polysaccharide at levels comparable to those for RpoS? strains. Our results show that RpoS is another regulator of Vi polysaccharide synthesis and contributes to VW variation in serotype Typhi, which has implications for the development of recombinant attenuated Salmonella vaccines in humans.
机译：Vi多糖的合成调控是肠炎沙门氏菌血清型Typhi的主要毒力决定因素，它受两个调控系统控制，即ompR - envZ 和 rscB - rscC ，它们对渗透压的变化做出响应。某些血清型Typhi菌株表现出Vi多糖的过表达，这掩盖了脂多糖O抗原的临床检测。自从对伤寒血清型进行初步研究以来，已观察到Vi多糖和O抗原展示的这种变化（VW变化）。在这项研究中，我们报道 rpoS 在Vi多糖中这种增加的表达中起作用。我们构建了多种同基因型Typhi突变体，它们的RpoS表达水平不同，并研究了 rpoS 产品在不同渗透压条件下在Vi多糖合成中的作用。在血清型Typhi突变体中还检测了Vi多糖的合成，其中 rpoS 的天然启动子被 araC P BAD 盒替代，因此 rpoS 的表达依赖于阿拉伯糖。 RpoS ？菌株显示Vi多糖的合成增加，在低和中等渗透压下掩盖了O抗原检测。相反，RpoS + 菌株显示Vi多糖的合成较低，并且观察到O抗原的检测增加。在指数生长过程中，当 rpoS 不稳定或水平较低时，血清型Typhi RpoS + 菌株以与RpoS 相当的水平过表达Vi多糖。菌株。我们的结果表明，RpoS是Vi多糖合成的另一种调节剂，并且有助于Tyty血清型的VW变异，这对人体内重组减毒 Salmonella 疫苗的开发具有重要意义。

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