White spot syndrome virus infection decreases the activity of antioxidant enzymes in Fenneropenaeus indicus.

White spot syndrome virus (WSSV) is the causative agent of White Spot disease of shrimp, causing mass mortalities in aquaculture. WSSV infection causes oxidative stress by the release of reactive oxygen species (ROS) that are toxic to the cells. The antioxidant enzymes associated with oxidative stress during the process of pathogenesis of WSSV in the infected tissues (hemolymph, hepatopancreas, gills and muscle) of Fenneropenaeus indicus were quantitatively determined at different time intervals post infection (0, 24, 48, 72 and after 72 h (moribund)). The level of lipid peroxidation, the activities of superoxide dismutase, catalase, glutathione peroxidase, and also the activities of the non-enzymic antioxidants glutathione-S-transferase, reduced glutathione and glutathione reductase in healthy and WSSV-infected hemolymph, hepatopancreas, gills and muscle of F. indicus showed marked differences at different times during the course of infection. The level of lipid peroxidation was higher in WSSV-infected muscle, hemolymph, gills and hepatopancreas than in uninfected F. indicus. Significant reductions in the activities of superoxide dismutase, catalase, glutathione-S-transferase, reduced glutathione, glutathione peroxidase and glutathione reductase were observed in WSSV-infected compared with uninfected animals. The increased lipid peroxidation in WSSV-infected shrimp may be due to increased oxidative stress in the cells as a result of depletion of antioxidant scavenger systems. The reduced activity of antioxidant enzymes in WSSV-infected animals could be due to inactivation of antioxidant enzymes by oxidative stress thereby generating free radicals, which accumulate in the cells. Further understanding of the biochemical alterations induced by viral infections, including changes in the antioxidant status and oxidative stress, could help to advance the therapeutic armamentarium for control of WSSV in shrimp.