Bacterial and viral diseases are considered major problems in prawn culture industry worldwide. However, the application of antibiotics to control disease was drug-resistance and environmental concern. ‘In this regards recombinant protein DNA or RNAi protein vaccines will be available (Chand & Sahoo, 2006; Chiu et al., 2010; Mishra, Singh, & Dagenais, 2000) which are species specific effect. Research toward better understanding of prawn defense factors is a possible induction mechanism which influence prawn health and resistance to disease, but the information gained has not yet led to any general conclusions. The use of natural immunostimulants in fish and shrimp culture to prevent diseases is a promising new development (G. Balasubramanian et al., 2008; Chand et al., 2006; Harikrishnan, Balasundaram, & Heo, 2011; Harikrishnan, Balasundaram, Jawahar, et al., 2011; B. Liu et al., 2010; M. Sakai, 1999; R. Shankar et al., 2011)’ which are biocompatible, biodegradable and safe for the environment and human health (Ortuno, Cuesta, Rodr’?guez, Esteban, & Meseguer, 2002). ‘However only few studies were done on OMP vaccine in shrimp. Penaeus monodon were immunized by the mixture of OMP vaccine of Vibrio parahaemolyticus and Vibrio alginolyticus at a rate of 50 and 75 mg/ml significantly reduced the mortalities of adult P. monodon against the V. parahaemolyticus and V. alginolyticus infection (Suprapto, 2005). Intramuscular administration of the OMP in tiger shrimp against V. alginolyticus significantly reduced the mortality (Maftuch et al., 2013).
However, there was no study of OMP vaccine in prawn culture to enhance immune system and diseases prevention. Considering the above points, we tried to evaluate incorporation different concentration of OMP (25, 50, 75 and 100 ??g/kg body weight of oral OMP vaccine diets on innate immunity and cumulative mortality for the first time in M. rosenbergii against A. hydrophila infection.
The bacterial count in the haemolymph significantly decreased in M. rosenbergii fed with 50 and 75 of oral OMP vaccine diets to the control. Phenoloxidase (PO) levels significantly increased in prawn fed with all diet on weeks 2 and 4 against A. hydrophila. In crustacean, melanization occurs when the cellular defence reactions are initiated (Ratcllife et al., 1985, Soderhall et al., 1986). PO is the key enzyme of melanin synthesis that occurs in haemolymph as an inactive proenzyme, prophenoloxidase (proPO) which is activated to form PO when it reacts with zymosan (carbohydrates from yeast cell walls), bacterial lipopolysaccharide (LPS), urea, calcium ions, trypsin, or heat (Soderhall and hall 1984, Johanson et al., 2000).
Several experiments have implied that apart from their role in melanization, components of the putative proPO activating system stimulate several cellular defense reactions including phagocytosis, nodule formation, encapsulation, and hemocyte locomotion (Soderhall et al., 1986, Johanson et al., 2000)’. The activated hemocytes also produce extra bactericidal substances, such as H2O2 and superoxide anion (O2-) that may increase protection from diseases (Song and Hiseh 1994).
PO is the terminal enzyme in the proPO system of the arthropod defense system which acts as both recognition and effector component by promoting cell-to-cell communication and subsequently eliminating pathogens …
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