Analysis of the virulence of various Vibrio Parahaemolyticus strains isolated in Vietnam

Abstract

After it being reported to cause significant losses among the shrimp farming industry in Asia, Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis syndrome (AHPND) was recognized as a dangerous shrimp disease. The causative agent of EMS/AHPND is found out as a specific strain of Vibrio parahaemolyticus. Beside the toxin proteins produced by the bacteria, the enzymatic characterization of Vibrio parahaemolyticus can be an important factor contributes to its virulence. The purpose of this study was to investigate the presence of EMS toxin and various extracellular enzymes which contribute to bacterial virulence in 17 Vibrio parahaemolyticus (V. parahaemolyticus) strains isolated from Penaeus monodon from different regions in Vietnam. Five extracellular enzymes tests including hemolysin, protease, lipase, elastase and lecithinase of V. parahaemolyticus were performed on both EMS and non-EMS strains. At the same time, the correlation between the presence of EMS-causative factor and extracellular virulence enzymes was also evaluated. The lecithinase activity appeared to be not significantly different among tested V. parahaemolyticus strains, while protease producing activity was absent in ten strains and presented in left 7 strains, distributed on both EMS and non-EMS groups. Lipase, elastase and hemolysin activity however could not be found on all strains. Keyword: Vibrio parahaemolyticus, Early Mortality Syndrome, Virulence extracellular enzyme, hemolysin, protease, lipase, elastase, lecithinase, Penaeus monodon.