Abstract:[Objective] To study the role of OmpR in biological characteristics and pathogenicity of Vibrio parahaemolyticus.[Methods] The ompR gene deletion mutant (ΔompR) and complementary strain (CΔompR) of Vibrio parahaemolyticus were constructed using homologous recombination.The differences of growth characteristics,motility and biofilm formation ability of each strain were analyzed.Furthermore,the effects of various strains on cell adhesion,cytotoxicity and mouse pathogenicity were compared.[Results]The ompR deletion had no significant effect on the growth characteristics,motility and cytotoxicity of V.parahaemolyticus.However,compared with the wild-type (WT) strain,ΔompR showed markedly reduced biofilm formation ability.Mice infected with ΔompR had a 25% higher survival rate and fewer lesions.The bacterial load of ΔompR in mouse heart,liver and kidney was significantly lower than that of the WT strain,whereas the complementary strain restored the virulence to the WT level.[Conclusion]OmpR is involved in the pathogenic process in mice.It is a potential virulence factor of V.parahaemolyticus.