The effects of leaf extract on the resistance of White-leg shrimp towards pathogenic .

leaf extract effect on the White-leg shrimp tolerance against were investigated in this study. Thirty shrimp post-larvae measured at approximately 1 cm were exposed for 24 h to 0.5, 1, 2, 3, 4, 5 and 6 g/L leaf extract and subsequently observed for survival and immune-related genes expression (, peroxinectin, penaeidin, crustin and transglutaminase), followed by determination of their tolerance and histological tissue profiles upon challenge. Survival of shrimps treated with 6 g/L of leaf extract improved by up to 95% to controls. Hsp70, crustin, and prophenoloxidase mRNA levels were observed to be 8.5, 10.4, and 1.5-fold higher, respectively. Histopathological analysis of the hepatopancreas and the muscle tissues revealed major tissue degeneration in -challenged shrimps but not in shrimps primed with leaf extract. Of all the dose examined, the best pathogen resistance results were obtained with a 24 h incubation of shrimp in 6 g/L methanolic leaf extract. The tolerance towards might be associated with the increased regulation of , prophenoloxidase and crustin upon exposure to the extract, all immune-related proteins essential for pathogen elimination in Penaeid shrimp. The present study primarily demonstrated that leaf extract is a viable alternative for enhancing post-larvae resistance against , a major bacterial pathogen in aquaculture.