Immunomodulatory response of superoxide dismutase in juvenile American white shrimp (Litopenaeus vannamei) exposed to immunostimulants

Immunomodulatory action of manganese superoxide dismutase (Mn-SOD) in juvenile American white shrimp (Litopenaeus vannamei) was studied. Shrimp between 0.7 and 1.0 g were immersed in aerated beta-glucan, lipopolysaccharide (LPS), fucoidan, and heat-killed Vibrio penaeicida solutions for 6 h. The enzymatic activity of Mn-SOD in entire organisms was investigated to evaluate whether different inummostimulants were able to induce antioxidant activity. The inummostimulants tested activated the immune system in juvenile shrimp and the highest antioxidant response was observed 48 h after the challenge with P-glucan, LPS, fucoidan and heat-killed V. penaeicida. The bacterm caused 3.2 times more Mn-SOD activity than the control group. Immunostimulated shrimp were challenged with live V. penaeicida on the tenth day and a second antioxidant response was observed 48 h after exposure to live pathogenic bacteria. Immunostimulated shrimp with P-glucan showed the highest Mn-SOD response (2.5 times more than the control group). This study showed the capacity of juvenile shrimp to enhance antioxidant response during a challenge with pathogenic bacteria after exposure to immunostimulants.