Terminalia catappa L. leaf extract interferes with biofilm formation of Vibrio parahaemolyticus and enhances immune response of Penaeus vannamei against acute hepatopancreatic necrosis disease (AHPND)

Abstract

Crude ethanolic extract from Terminalia catappa L. leaves was investigated for its ability to interfere with biofilm formation of acute hepatopancreatic necrosis disease (AHPND)-causing and a reference Vibrio parahaemolyticus strains and modulate the immune response of Penaeus vannamei shrimp postlarvae. Results showed that biofilms formed by both AHPND-causing and reference strains of V. parahaemolyticus were rendered susceptible to dispersal upon treatment with the sublethal concentration of the extract. Furthermore, results of the qPCR analyses showed upregulation of six immune-related genes after 7 and 14 d of feeding. Pre-infection survival rates equivalent to the shrimp fed with un-supplemented feed suggest that T. catappa extract is safe for shrimp consumption. Upon infection with the AHPND strain, V. parahaemolyticus R1, the survival rate of the treatment group was 77% - significantly greater than those fed with un-supplemented feed. Similarly, those fed with T. catappa-supplemented feed and subsequently infected with V. parahaemolyticus ATCC17802 had a 93% survival rate, which is as high as the uninfected control group. These results ultimately indicate that feed supplementation with T. catappa increases the survival rate of the shrimp, possibly via attenuation of V. parahaemolyticus pathogenesis and stimulation of the shrimp's immune response against infections.