Figure 6: Immunological changes of white shrimp Litopenaeus vannamei injected with PBS and WSSV at different time intervals (0, 2, 4, 6, 8, 10, 12, 24, 36 and 48 h) of post infection. A. Prophenoloxidase activity B. Superoxide dismutase activity C. Superoxide anion activity D. Nitrate activity E. Nitrite activity (OD490 nm).