ABSTRACT
Objective:To study the virulence-related functions and the pathogenic molecular mechanism of the transcription factor OmpR in Vibrio vulnificus. Methods:The Vibrio vulnificus ompR mutant (Δ ompR) strain was constructed using a markerless gene deletion system. Changes in the tolerance to osmotic pressure, swarming mobility and biofilm synthesis were detected by growth curve, swimming assay and crystal violet assay, respectively. Colony counting methods were used to analyze the cytoadherence of the Δ ompR strain. The cytotoxicity of the Δ ompR strain was measured by lactate dehydrogenase (LDH) releasing test. Real-time fluorescent quantitative RT-PCR (qRT-PCR) was used to detect the changes in the expression of target genes including ompN, ompU, ompA and hcp2 at mRNA level in the Δ ompR. Results:The Δ ompR strain was constructed successfully. Compared with the wild-type strain, the mutant strain showed decreased tolerance to high osmotic pressure, suppressed capability of biofilm formation and reduced cytoadherence and cytotoxicity, whereas no significant difference in motility was detected. The expression of ompN gene at mRNA level in the Δ ompR strain was down-regulated ( P<0.05), while the expression of other target genes showed no significant changes. Conclusions:The transcription factor OmpR regulated the tolerance to high osmotic pressure, biofilm formation, cytoadherence and cytotoxicity in Vibrio vulnificus.