The two-component system, BasSR, is involved in the regulation of biofilm and virulence in avian pathogenic .

Avian pathogenic (APEC) is a subgroup of extra-intestinal pathogenic (ExPEC) strains that cause avian colibacillosis, resulting in significant economic losses to the poultry industry worldwide. It has been reported that a few two-component signal transduction systems (TCS) participate in the regulation of the virulence factors of APEC infection. In this study, a -deficient mutant strain was constructed from its parent strain APECX40 (WT), and high-throughput sequencing (RNA-seq) was performed to analyse the transcriptional profile of WT and its mutant strain XY1. Results showed that the deletion of down-regulated the transcript levels of a series of biofilm- and virulence-related genes. Results of biofilm formation assays and bird model experiments indicated that the deletion of inhibited biofilm formation and decreased bacterial virulence and colonization . In addition, electrophoretic mobility shift assays confirmed that the BasR protein could bind to the promoter regions of several biofilm- and virulence-related genes, including , and . This study suggests that the BasSR TCS might be a global regulator in the pathogenesis of APEC infection. Transcriptional profiling showed that BasSR might be a global regulator in APEC. BasSR increases APEC pathogenicity . BasSR positively regulates biofilm- and the virulence-associated genes. BasSR can bind to the promoter regions of virulence-associated genes , and .