Phloroglucinol-Mediated Hsp70 Production in Crustaceans: Protection against in and .

The halophilic aquatic bacterium, , 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 model is used to establish whether a phenolic compound phloroglucinol is effective against the AHPND strain MO904. We found that pretreatment with phloroglucinol, at an optimum concentration (30 µM), protects axenic brine shrimp larvae against infection and induced heat shock protein 70 (Hsp70) production (twofolds or more) as compared with the control. We further demonstrated that the -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 infection. The study was validated in xenic model and in a system. Pretreatment of xenic brine shrimp larvae (30 µM) and larvae (5 µM) with phloroglucinol increases the survival of xenic brine shrimp and larvae against subsequent challenge. Taken together, our study provides substantial evidence that the prooxidant activity of phloroglucinol induces Hsp70 production protecting brine shrimp, , and freshwater shrimp, , against the AHPND strain MO904. Probably, phloroglucinol treatment might become part of a holistic strategy to control AHPND in shrimp.