Antioxidant enzyme activity in pacific whiteleg shrimp (Litopenaeus vannamei) in response to infection with white spot syndrome virus

Abstract

White spot syndrome virus is a virulent pathogen that affects most crustaceans. Reactive oxygen species are produced by the immune system that defends the host against foreign microorganisms. This study examined the antioxidant enzymes and oxidative damage in tissues (hemolymph, digestive gland, gills, and muscle) of Pacific whiteleg shrimp (Litopenaeus vannamei) infected with the disease by intramuscular injection of the virus. Viral loads were confirmed by real-time PCR. The levels of oxidative damage (lipid peroxidation and protein carbonyl), the activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and glutathione S-transferase) were quantified in uninfected and infected tissues. Lipid peroxidation and protein carbonyl levels were higher in infected specimens compared to uninfected controls. A significant reduction in antioxidant enzyme activities was found at 48h post-infection in all tissues analyzed. These results suggest that oxidative stress and tissue damage via inactivation of antioxidant enzymes in infected shrimps result in system failure and sudden death.