Physiological, biochemical and genetic responses of black tiger shrimp (Penaeus monodon) to differential exposure to white spot syndrome virus and Vibrio parahaemolyticus

Abstract

The black tiger shrimp (Penaeus monodon) represents a major crustacean aquaculture species globally. Outbreaks of diseases caused by two particular pathogens, Vibrio parahemolyticus (VP) and white spot syndrome virus (WSSV) severely hamper the production performance of this species. The present study investigated the effects of different doses of the two pathogens on physiological/biochemical parameters and differential gene expression in P. monodon. This study involved 10 different experimental groups including nine treatments (three doses of VP: T1 – T3, three doses of WSSV: T4 – T6 and three combined VP + WSSV doses: T7 – T9) and a control. VP and WSSV treatments significantly reduced hemocyte counts of shrimp hemolymph (P < 0.05). Different treatments showed 2–4 fold increase in hemolymph glucose and serotonin levels over the control shrimps. Pathogenic treatments significantly altered expression pattern of the selected set of candidate genes. The α-amylase (growth gene) showed reduced expression (1.5–3 fold lower) in treatments while immune response genes (Prophenoloxidase and Lysozyme) showed significantly higher expression levels (2–3 fold higher) in treatment groups compared to the control. Significantly higher O2 consumption rates in the pathogen-treated shrimp, T1 – T9 (P < 0.05) indicate that these shrimp faced pathogenic stress. Shrimp in the control group showed 1.5–2 fold higher growth (increase in body weight) compared to treatment groups (T1 – T9). Results indicate that different doses of pathogenic exposure significantly altered the expression of candidate genes together with changes in physiological (O2 consumption rates) and biochemical (hemocyte counts, glucose and serotonin levels of hemolymph) parameters that adversely affected growth and mortality of experimental shrimps.