Zebrafish as a model for Vibrio parahaemolyticus virulence.

Vibrio parahaemolyticus is a Gram-negative, naturally occurring marine bacterium. Subpopulations of strains belonging to this species cause an acute self-limiting gastroenteritis in humans and, less commonly, wound infections. In vivo models to differentiate avirulent and virulent strains and evaluate the pathogenic potential of strains of this species have been largely focused on the presence of known virulence factors such as the thermostable direct haemolysin (TDH), the TDH-related haemolysin (TRH) or the contributions of the type 3 secretion systems. However, virulence is likely to be multifactorial, and additional, yet to be identified factors probably contribute to virulence in this bacterium. In this study, we investigated an adult zebrafish model to assess the overall virulence of V. parahaemolyticus strains. The model could detect differences in the virulence potential of strains when animals were challenged intraperitoneally, based on survival time. Differences in survival were noted irrespective of the source of isolation of the strain (environmental or clinical) and regardless of the presence or absence of the known virulence factors TDH and TRH, suggesting the influence of additional virulence factors. The model was also effective in comparing differences in virulence between the wild-type V. parahaemolyticus strain RIMD2210633 and isogenic pilin mutants ΔpilA and ΔmshA, a double mutant ΔpilA : ΔmshA, as well as a putative chitin-binding protein mutant, ΔgbpA.