In vivo transcriptome analysis of avian pathogenic Escherichia coli under the control of RstA/RstB two-component regulatory system. In vivo transcriptome analysis of avian pathogenic Escherichia coli under the control of RstA/RstB two-component regulatory system

APEC cause avian colibacillosis in poultry, characterized by the systematic infection, such as septicemia, airsacculitis, and pericarditis. APEC mainly use two-component regulatory systems (TCSs) to deal with the stressing environments in host during their infection. Whereas most TCSs in E.coli are well characterized, the characterization of RstA/RstB in APEC has not been thoroughly investigated. To understand the whole picture of RstA/RstB regulation, especially its role in virulence regulation, transcriptional analysis of the effect of rstAB deletion was performed in vivo. We compared the transcriptome of rstAB mutant and its wild-type strain during their growth in bloodstream of challenged chickens. In total, the transcripts of 85 genes were down-regulated by rstAB deletion while 113 were up-regulated at least twofold (cutoff limitation for fold change >2 or <0.5 and Cuffdiff P-value <0.05 was used to select differential expression genes). Our data showed that the RstA/RstB was a by-function regulator system, acting as both an activator and a repressor. The RstAB mainly regulated systems involved in nitrogen metabolism, bacterial virulence, iron acquisition and acid resistance. Overall design: We contructed the rstAB mutant and compared the transcriptome of rstAB mutant and its wild-type strain during their growth in bloodstream of challenged chickens

禽致病性大肠杆菌（Avian Pathogenic Escherichia coli, APEC）可引发家禽禽大肠杆菌病，其特征为全身性感染，涵盖败血症、气囊炎与心包炎。APEC主要通过双组分调控系统（two-component regulatory systems, TCSs）应对感染宿主过程中的胁迫环境。尽管大肠杆菌的多数双组分调控系统已得到充分表征，但APEC中RstA/RstB系统的研究尚未深入透彻。为全面解析RstA/RstB的调控机制，尤其是其在毒力调控中的作用，本研究开展了rstAB基因缺失的体内转录分析。我们比较了rstAB突变株与其野生型菌株在攻毒鸡血液中生长时的转录组。以折叠变化>2或<0.5、Cuffdiff检验P值<0.05作为差异表达基因筛选阈值，最终共发现85个基因在rstAB缺失后转录本下调（折叠变化<0.5），113个基因转录本上调至少2倍。本研究数据表明，RstA/RstB是一种兼具激活与抑制功能的双功能调控系统。RstAB主要调控氮代谢、细菌毒力、铁摄取及耐酸相关的生理通路。总体实验设计：我们构建了rstAB基因缺失突变株，并比较了其与野生型菌株在攻毒鸡血液中生长时的转录组。