Functional analysis and pathogenicity of avian pathogenic Escherichia coli of virulence gene yqeH

Abstract:

[Background] Avian pathogenic Escherichia coli (APEC) can cause avian acute or subacute infection, E. coli type III secretion system 2 (ETT2) is a new type III secretion system found in recent years. The effect of virulence gene yqeH on APEC pathogenicity in APEC is unclear. [Objective] To explore the role of yqeH in the pathogenesis of APEC, so as to lay a foundation for further research on the pathogenesis of ETT2. [Methods] The yqeH deletion strain ΔyqeH and its complementary strain CΔyqeH were constructed by Red homologous recombination technology. The effects of yqeH on the biological function of APEC were analyzed by motility test, biofilm formation ability, stress resistance tests and serum resistance test. The effect of yqeH on host infection of APEC was investigated by cell adhesion and invasion test, pathogenicity test and inflammatory factor expression level detected by fluorescence quantitative PCR.[Results] The deletion strain ΔyqeH and the complementary strain CΔyqeH were successfully constructed. Compared with the wild APEC81 strain, ΔyqeH strain showed lower biofilm formation ability and movement ability, lower tolerance to acid, alkali, osmotic pressure and oxidative shock, lower serum resistance and lower pathogenicity. The adhesion and invasion ability of ΔyqeH to the epithelial cells of chicken trachea mucosa were significantly decreased. Compared with wild strain APEC81, the transcription level of inflammatory factors in chicken tracheal epithelial cells infected by ΔyqeH significantly reduced. [Conclusion] yqeH can regulate biofilm formation, motility, stress resistance, adhesion and invasion ability, inflammatory factor expression, and serum resistance of APEC, thereby regulate the pathogenicity of APEC.

Key words:avian pathogenic E. coli;ETT2;yqeH;inflammatory factors;pathogenicity