Effect of Rotenone Immersion on Enhancement of the Immune Response of White Shrimp Litopenaeus vannamei and Its Resistance Against Vibrio alginolyticus

Abstract

Hemogram, phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, phagocytic activity, and clearance efficiency against Vibrio alginolyticus were examined when the white shrimp Litopenaeus vannamei (10.3 ± 1.7 g) was immersed in seawater (35 per mille) containing different concentrations of rotenone (0, 0.5, 1, and 2 mg/l) for 6, 12, 24, and 48 h. Hyaline cells (HCs), granular cells (GCs, including semi-granular cells), total hemocyte count (THC), PO activity, RBs, SOD activity, and GPx activity of shrimp that immersed in seawater containing rotenone at 1 mg/l increased significantly after 24 h. White shrimp that were immersed in seawater containing rotenone at 1 mg/l showed increased phagocytic activity and clearance efficiency of V. alginolyticus over 24~48 h and 12~48 h, respectively. In another experiment, white shrimp immersed in seawater containing different concentrations of rotenone for 24 h were challenged with V.alginolyticus at 4 × 10^5 colony-forming units (cfu) shrimp^(-1), and then placed in seawater. The survival rate of shrimp immersed in seawater containing rotenone at 1 mg/l and 2 mg/l was significantly higher than that of control shrimp after 6 h, as well as at the termination of the experiment (96 h after the challenge). It was therefore concluded that white shrimp immersed in water containing rotenone at 1 mg/l exhibited enhanced immune ability, as well as protection against V. alginolyticus infection.