Phloroglucinol-Mediated Hsp70 Production in Crustaceans: Protection against Vibrio parahaemolyticus in Artemia franciscana and Macrobrachium rosenbergii

Abstract

The halophilic aquatic bacterium, <i>Vibrio parahaemolyticus</i>, is an important aquatic pathogen, also capable of causing acute hepatopancreatic necrosis disease (AHPND) in shrimp resulting in significant economic losses. Therefore, there is an urgent need to develop anti-infective strategies to control AHPND. The gnotobiotic <i>Artemia</i> model is used to establish whether a phenolic compound phloroglucinol is effective against the AHPND strain <i>V. parahaemolyticus</i> MO904. We found that pretreatment with phloroglucinol, at an optimum concentration (30 µM), protects axenic brine shrimp larvae against <i>V. parahaemolyticus</i> infection and induced heat shock protein 70 (Hsp70) production (twofolds or more) as compared with the control. We further demonstrated that the <i>Vibrio</i>-protective effect of phloroglucinol was caused by its prooxidant effect and is linked to the induction of Hsp70. In addition, RNA interference confirms that phloroglucinol-induced Hsp70 mediates the survival of brine shrimp larvae against <i>V. parahaemolyticus</i> infection. The study was validated in xenic <i>Artemia</i> model and in a <i>Macrobrachium rosenbergii</i> system. Pretreatment of xenic brine shrimp larvae (30 µM) and <i>Macrobrachium</i> larvae (5 µM) with phloroglucinol increases the survival of xenic brine shrimp and <i>Macrobrachium</i> larvae against subsequent <i>V. parahaemolyticus</i> challenge. Taken together, our study provides substantial evidence that the prooxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp, <i>A. franciscana</i>, and freshwater shrimp, <i>M. rosenbergii</i>, against the AHPND <i>V. parahaemolyticus</i> strain MO904. Probably, phloroglucinol treatment might become part of a holistic strategy to control AHPND in shrimp.