The phase variation between wrinkly and smooth colony phenotype affects the virulence of Vibrio parahaemolyticus.

Vibrio parahaemolyticus, the causative agent of seafood-associated gastroenteritis, undergoes wrinkly and smooth colony switching on the plate. The wrinkly spreader grew faster, had stronger motility and biofilm capacity when compared with the smooth one. However, whether the two phenotypes differ in their virulence still needs to be further investigated. In this study, the data showed that the smooth spreader had stronger virulence phenotypes, including the cytotoxicity against HeLa cells, antibacterial activity against E. coli, adhesive capacity toward HeLa cells, and lethality in zebrafish, relative to the wrinkly one. However, the colony morphology variation had no influence on the haemolytic activity. The mRNA levels of major virulence genes including T3SS1, T6SS1, and T6SS2 were significantly enhanced in the smooth colonies relative to those in the wrinkly colonies. Taken together, the presented work highlighted the different virulence profiles of the wrinkly and smooth colony phenotypes.