α-Phellandrene enhances the immune response and resistance against Vibrio alginolyticus in white shrimp (Litopenaeus vannamei)

Innate immunity and resistance against Vibrio alginolyticus in white shrimp, Litopenaeus vannamei, that received alpha-phellandrene were examined. The results indicated that the percent survival of shrimp receiving 4, 8, and 12 mu g g(-1) alpha-phellandrene was significantly higher than that of control shrimp after 72 h (p < 0.05). In a separate experiment, the phenoloxidase (PO), respiratory bursts, superoxide dismutase (SOD), and phagocytic and lysozyme activity of L. vannamei receiving 8 and 12 mu g g(-1) alpha-phellandrene were significantly higher than those of the other groups upon challenge with V. alginolyticus at 24-60, 36-60, 12-60, 12-72 and 48-72 h, respectively. However, no significant differences in the total haemocyte counts (THC) of L. vannamei receiving any dose of alpha-phellandrene and of control shrimp were observed at 12-72 h. The expression (mRNA transcripts) of the immune genes prophenoloxidase (proPO), LPS- and beta-1,3-glucan-binding protein (LGBP) and peroxinectin (PE) of shrimp receiving alpha-phellandrene at 8 and 12 mu g g(-1) significantly increased after challenge with V. alginolyticus for 72 h (p < 0.05). We conclude that the immune ability and resistance against V. alginolyticus infection increased in L. vannamei receiving > 4 mu g g(-1) alpha-phellandrene. These results indicated that a-phellandrene plays an important role in the innate immunity of white shrimp.