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. 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