Two-component system rcsC gene affects pathogenicity and associated biological characteristics of avian pathogenic Escherichia coli

Abstract:

[Objective] The two-component system (TCS) Rcs is involved in the regulation of bacterial adaptation to external environment and survival. The aim of this study is to elucidate effects of sensor kinase RcsC on associated biological characteristics and virulence of avian pathogenic Escherichia coli (APEC).[Methods] We constructed the rcsC gene mutant and complementary strain of APEC by the Red recombination system and complementation plasmid. Then we compared the growth curve, motility, biofilm formation, agglutination, pathogenicity and virulence gene transcription levels of mutant, wild-type and complementary strains.[Results] rcsC gene deletion had no influence on bacterial growth. However, inactivation of rcsC gene resulted in enhanced motility, decreased biofilm formation and increased agglutination. Bacterial adherence and invasion assays showed that RcsC contribute to the invasion of APEC to DF-1 cells, whereas, it did not affect the adhesion capacity. Moreover, rcsC gene mutant strain exhibited attenuated virulence in ducks. Quantitative real-time PCR analysis demonstrated that the transcription levels of virulence genes ompA, aatA, fyuA and luxS were significantly decreased in mutant strain. Whereas, the fimC and tsh transcription levels were significantly upregulated.[Conclusion] These data indicated that RcsC play roles in regulation of bacterial motility, biofilm formation, agglutination and virulence of APEC.

Key words:avian pathogenic Escherichia coli;two component system;rcsC;biological characteristics;virulence