中文摘要：

目的：研究伤寒沙门菌ssrB基因在氧应激早期对其他基因表达的调节。方法：通过同源重组的方法利用自杀质粒制备伤寒沙门菌ssrB基因缺陷变异株;采用伤寒沙门菌全基因组芯片比较野生株和ssrB基因缺陷变异株在氧应激早期的基因表达差异,并对其中部分表达差异基因进行实时定量PCR验证;利用HeLa细胞进行细菌侵袭实验,研究ssrB基因对伤寒沙门菌侵袭能力的影响。结果：成功制备伤寒沙门菌ssrB基因缺陷变异株;基因芯片结果分析显示,在氧应激早期,与野生株相比,伤寒沙门菌ssrB基因缺陷变异株有68个基因表达下调,有20个基因表达上调,其中与侵袭相关的基因表达下调。实时定量PCR与芯片结果一致。ssrB基因缺陷变异株侵袭上皮细胞的能力仅为野生株的34.6%。结论：SsrB在伤寒沙门菌氧应激早期对基因表达起重要调节作用,并且能够增强伤寒沙门菌侵袭上皮细胞的能力。

英文摘要：

Objective： To investigate the regulation of ssrB on gene expression of Salmonella enterica serovar Typhi（S.Typhi） at early-stage of oxidative stress.Methods： The ssrB deleted mutant of S.Typhi was generated through homologous recombination mediated by suicide plasmid;the gene expression profiles of the wild-type strain and the ssrB deleted mutant at early-stage of oxidative stress was investigated by genomic microarray assay;qRT-PCR was performed to further validate the results of microarray assay.The HeLa cells were invaded by S.Typhi to explore the influence of ssrB on invasion of epithelial cells.Results： The ssrB deleted mutant of S.Typhi was prepared successfully;analysis of genomic assay showed that,compared to the wild-type strain,68 genes were up-regulated and 20 genes were down-regulated in the ssrB deleted mutant at early stage of oxidative stress.The results of qRT-PCR assay were consistent with the results of microarray assay.The ability of the ssrB deleted mutant to invade the epithelial cells was only 34.6% of the wild-type strain.Conclusion： SsrB of S.Typhi played an important role in regulating gene expression at early stage of oxidative stress and enhanced the ability of S.Typhi to invade epithelial cells.