Salmonella enteritidis has emerged as one of the most important food-borne pathogens for humans, and the formation of biofilms by this species may improve its resistance to disadvantageous conditions. The spiA gene of Salmonella typhimurium is essential for its virulence in host cells. However, the roles of the spiA gene in biofilm formation and virulence of S. enteritidis remain unclear. In this study we constructed a spiA gene mutant with a suicide plasmid. Phenotypic and biological analysis revealed that the mutant was similar to the wild-type strain in growth rate, morphology, and adherence to and invasion of epithelial cells. However, the mutant showed reduced biofilm formation in a quantitative microtitre assay and by scanning electron microscopy, and significantly decreased curli production and intracellular proliferation of macrophages during the biofilm phase. In addition, the spiA mutant was attenuated in a mouse model in both the exponential growth and biofilm phases. These data indicate that the spiA gene is involved in both biofilm formation and virulence of S. enteritidis.
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Funding
This study was supported by the:
National Natural Science Foundation of China
(Award 30871872)
Qing Lan Project
Program for Changjiang Scholars and Innovative Research Team in University
High Technology R&D Program of China
(Award 2006AA10A206)
National Natural Science Foundation of China
(Award 30425031)
National Key Technology R&D Program
(Award 2009BADB9B01)
National Sciences Foundation of Jiangsu Province
(Award BK2008011)
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