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Early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND)is currently the most significant disease of shrimp in farms of Vietnam, Thailand, Malaysia, China and Mexico, and there is a great risk that it may spread to other shrimp farming countries. Although, an array of sophisticated detection tools for AHPND available, there is a need for a sensitive, simple and rapid detection method.In this study, a simple, sensitive, rapid and polyclonal antibody-based farmer-friendly flow-through assay (FTA) test has been developed for the detection of AHPND pathogen. The recombinant Photorhabdus insect-related (Pir) A toxin-like protein of AHPND pathogen was used to immunize rabbits at 21-day interval observed for highest antibody titre after third booster by ELISA. The raised rabbit antiserum was purified by affinity chromatography and characterized by Western blot. The antiserum showed no cross-reactivity with AHPND-free Vibrio parahaemolyticus, V. anguillarum, White Spot Virus (WSV), Aeromonashydrophila and Aphanomycesinvadans. This polyclonal rabbit antiserum was used to develop a farmer-friendly FTA test for the detection of AHPND pathogen. This simple FTA testis is more sensitive and could detect PirA VP toxin up to 0.121 µg/ml, compared with 0.242 µg/ml by immunodot assay. Furthermore, FTA test requires only 8-10 min for completion, compared with 3 hr by immunodot thus found to be more sensitive, specific and cost-effective. Collectively, sensitive FTA test would help shrimp farmers to take real-time management decisions, especially emergency harvest and finally be a better hope for the prevention of AHPND.

In recent decades, pollution of freshwater and riverine ecosystems is indorsed to heavy metals contamination. Among various causes, heavy metals are the most concern. Many aquatic organisms have the ability to inhabit in contaminated environments, due to their defense mechanisms that allow detoxification, excretion, anti-oxidant protection and stress response. Lamellidens marginalis have the potential to accumulate the heavy metals. In the present study, the mussels were exposed to 1, 5, 10 and 15 ppm concentration of mercuric chloride for 96 hrs. Enzymatic and antioxidant parameters including catalase (CAT), superoxide dismutase (SOD), lactate dehydrogenase (LDH), hydrogen peroxide (HP) and lipid peroxidation (LPO) levels were used as effective criteria. All the parameters showed responses in gills, abductor muscle, mantle tissue, gills and gonads with exposure to HgCl 2 . Collectively, these parameters could be used as biomarker for heavy metals contamination in aquatic system using L. marginalis.

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