Volume 31 Issue 8 - April 27, 2018 PDF
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Integrative research outcomes of shrimp immunity, pathogenesis and microbiomics
Han-Ching Wang*, Hsing-Ying Lin, Chen-Han Huang, Yun-Chiang Lan, Chih-Han Chang, and Hsiang-Chen Chui
Department of Biotechnology and Bioindustry Sciences, National Cheng Kung University
 
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【107 Taiwan Outstanding Women in Science】Special Issue

Various diseases, currently threaten shrimp aquaculture, especially in developing countries of Asia. The WSD (white spot disease), caused by WSSV (white spot syndrome virus), and AHPND (acute hepatopancreatic necrosis disease), caused by a virulent strain of the Vibrio parahaemolyticus bacterium, are the two most harmful diseases prevalent in shrimp industry. These diseases have caused huge economic losses globally. Therefore, there is an urgent need to develop effective strategies to combat these diseases. A scientifically comprehensive (evidence-based research) approach is essential to determine ecofriendly and sustainable solutions. Our team uses a state-of-the-art integrated systems-biology approach to study complex biological phenomena, with a focus on translational research outcomes. In addition to basic science, we consistently seek practical ways to apply our research outcomes to reduce the impact of diseases in shrimp farming.

Our research topics and specific contributions to shrimp science are as follows:
   
  1. The immune-related role of the Down syndrome cell adhesion molecule (Dscam) in shrimp: We conducted pioneering research in shrimp immune priming and investigated the role of shrimp Dscam as a novel host defense system. Dscam, the proposed antibody-like analog identified in shrimp, provides a scientific basis for a range of potential shrimp vaccination strategies. Our 8 years of research work characterizing Dscam-mediated immunity is recognized internationally.
  2. Extracellular traps (ETs) - a novel immune response in shrimp: Our team was the first to report extracellular traps as an anti-bacterial immune response in invertebrates. Shrimp ETs are comprised of nuclear DNA bound with histones. We identified and reported pathogens that can trigger ETs in shrimp hemocytes. Furthermore, our studies encouraged other international research groups to continue research on these novel shrimp immune responses.
  3. Identification of metabolic pathways essential for WSSV replication: Initially, we started with a basic research question and subsequently developed an in vivo model, using genomics, proteomics, metabolomics and other systems biology strategies. I have led five collaborative academic research teams to to focus on global interactions between shrimp and WSSV. Our teams characterized key host mechanisms involved in virus replication. We were the first to report that an invertebrate virus (WSSV) can trigger the cancer cell-like Warburg effect (i.e. aerobic glycolysis) in an invertebrate (white shrimp). We reported that WSSV triggers a Warburg effect, characterized by glutaminolysis and altered lipid metabolism (Fig. 1) to complete its replication cycle. In addition, we identified key host factors involved in triggering a Warburg effect. Our findings are being successfully applied in selection-based breeding of WSSV-resistant shrimp.
  4. Characterization of the AHPND pathogen: We successfully isolated and characterized the unique, virulent plasmid present in AHPND-causing strain of Vibrio parahaemolyticus. Subsequently, using a systems biology approach, we confirmed colonization of AHPND-causing bacteria in shrimp stomach. We believe that relatively loose adhesions between stomach cells enable the AHPND binary toxin to penetrate the stomach wall and damage the hepatopancreas. Our studies revealed a deep understanding of the AHPND pathogenesis and encouraged us to develop a standard diagnostic platform for detecting AHPND-causing bacteria. Consequently, it is now possible to select pathogen-free shrimp and maintain pathogen-free shrimp culture environment.
  5. Linking intestinal microbiota to shrimp health and AHPND: Our recent findings documented the relationship between the gut microbiota and cultured shrimp health status. We achieved this in collaboration with the international shrimp industry and Prof. Jer-Horng Wu, Department of Environmental Engineering, NCKU. Intriguingly, we noticed that the microbial diversity in shrimp stomach was significantly reduced during AHPND infection. This was evident with the drop in Shannon index by 57.6%. In a span of <7 days, Vibrio and Candidatus Bacilloplasma became predominant species in the microbiota, thereby altering the complexity of interaction network and species-to-species connectivity. A better understanding of the cross-talk between shrimp disease and gut microbiome provides huge prospects for strategies to control disease by using probiotics and other potential natural compounds to manipulate composition of gut bacteria in healthy shrimp.

Fig. 1 Specific metabolic responses in WSSV-infected shrimp cells.
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