In vitro disinfection efficacy and clinical protective effects of common disinfectants against acute hepatopancreatic necrosis disease (AHPND)-causing Vibrio isolates in Pacific white shrimp Penaeus vannamei

Acute hepatopancreatic necrosis disease (AHPND) is one of the most significant bacterial diseases in global shrimp culture, causing severe economic losses. In the present study, we carried outin vitroantimicrobial tests to investigate the disinfection efficacy of 14 common disinfectants toward different AHPND-causingVibriospp., including eight isolates ofV. parahaemolyticus, four isolates ofV. campbellii, and one isolate ofV. owensii. Polyhexamethylene biguanidine hydrochloride (PHMB) was revealed to possess the strongest inhibitory activity. Through analyzing and evaluating the results of antimicrobial tests and acute toxicity test, we selected PHMB and hydrogen peroxide (H2O2) for further clinical protection test. Clinical manifestations indicated that both PHMB (2 mg/L and 4 mg/L) and H2O2(12 mg/L) could effectively protect juvenilePenaeus vannameifrom the infection ofV. parahaemolyticusisolateVp362 at 10(6)CFU/ml, and the survival rate was over 80%. When the bacterial concentration was reduced to 10(5)CFU/ml, 10(4)CFU/ml, and 10(3)CFU/ml, the survival rate after treated by 1 mg/L PHMB was 64.44%, 93.33%, and 100%, respectively. According to the results, PHMB and H(2)O(2)showed a lower toxicity while a better protection activity, particularly against a lower concentration of the pathogens. Therefore, these two disinfectants are proved to be promising disinfectants that can be applied to prevent and control AHPND in shrimp culture. Moreover, the methods of this study also provided valuable information for the prevention of other important bacterial diseases and suggested a reliable means for screening potential drugs in aquaculture.