Department of Biochemistry and Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.
International Joint Cancer Institute, Navy Medical University, Shanghai, 200433, China.
Microb Pathog. 2018 Nov;124:191-197. doi: 10.1016/j.micpath.2018.08.050. Epub 2018 Aug 24.
Salmonella enterica serovar Typhi (S. Typhi) is a human enteropathogen that can overcome oxidative stress and survive in macrophages. OxyR is an important part of the antioxidant defense system. S. Typhi expresses a virulence (Vi) polysaccharide capsular antigen, which provides the bacterium with the ability to avoid host defenses and suppress detection by the innate immune system. This study investigated the effect of OxyR on Vi antigen in S. Typhi. In the oxyR mutant strain, microarray analysis, quantitative real time PCR and β-galactosidase assay confirmed that the viaB operon was positively regulated by OxyR. The Vi enzyme-linked immunosorbent assay and flow cytometry results showed that Vi capsule level was decreased in the oxyR mutant strain. Also, the EMSA revealed that OxyR directly binds to the promoter region of tviA. Thus, we propose that S. Typhi OxyR positively regulates expression of Vi capsule antigen in a direct manner.
肠道沙门氏菌血清型 Typhi（S. Typhi）是一种人类肠道病原体，能够克服氧化应激并在巨噬细胞中存活。OxyR 是抗氧化防御系统的重要组成部分。S. Typhi 表达一种毒力（Vi）多糖荚膜抗原，使细菌能够逃避宿主防御并抑制先天免疫系统的检测。本研究探讨了 OxyR 对 S. Typhi 中 Vi 抗原的影响。在 oxyR 突变株中，通过微阵列分析、定量实时 PCR 和 β-半乳糖苷酶测定证实，oxyR 正向调节 viaB 操纵子。Vi 酶联免疫吸附试验和流式细胞术结果表明，oxyR 突变株中 Vi 荚膜水平降低。此外，EMSA 显示 OxyR 直接结合 tviA 启动子区域。因此，我们提出 S. Typhi OxyR 以直接方式正向调节 Vi 荚膜抗原的表达。
