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Seminar 916

Date:2020-12-15 Update:2020-12-15

Establishment of crustacean white spot syndrome virus detection method and animal infection model

Yi-Ping Lu

 

Abstract

Shrimp white spot syndrome virus (WSSV) is one of the most important shrimp viral diseases that harmful to the aquaculture industry in Taiwan. The development of the   technology for establishment of wssv free shrimp is currently needed by the industry. By adding antiviral agents to shrimp feed is one of the resolutions, but it requires establishing an appropriate animal model to evaluate its effectiveness. In this study, PCR and Real-time PCR were used to establish a qualitative and to quantitative method for wssv nucleic acid detection in shrimp specimens. Immunocytochemistry technique was used to establish a method for detecting virus distribution in tissues. Then, white shrimps were artificial inoculation of seed virus by injection and soaking method to establish an animal model of wssv infection. They can further apply for production of seed virus, challenge of experiment shrimp and the effectiveness evaluation of antiviral agent methods. Through the above-established method, a high-concentration seed virus without contaminating other pathogens has been stably produced, and an animal infection model of white shrimp by injection and soaking routes has been established and its LD50 and LT50 have been confirmed. The results of immunochemical staining experiments show that the previously developed anti-wssv egg yolk antibody has specific immunological binding activity to the wssv antigen in the infected shrimp tissues. This antibody can be further evaluated the effectiveness in the future to protect shrimp against from wssv. It can also be used to develop rapid detection reagents for wssv.

 

The surveillance of important pathogens in shrimp and environmental samples from hatchery and grow-out farm

I-Wen Chen

 

Abstract

To prevent new emerging diseases cause damage in the white shrimp aquaculture industry, the surveillance of OIE list diseases and 2 new emerging diseases, including white spot disease virus (WSD), infectious hypodermal and hematopoietic necrosis virus (IHHNV), taura syndrome virus (TSV), yellowhead disease virus (YHDV), infectious myonecrosis virus (IMNV), necrotising hepatopancreatitis (NHP), acute hepatopancreatic necrosis disease (AHPND), Enetrocytozoon hepatopanei (EHP) and covert mortality disease virus (CMDV), of shrimp in hatcheries and grow-out farms, and associated environmental factors(larvae, raw feed, pond water and soil) were executed. After having analyzing the results of the investigation, we next aimed to assist shrimp farmers to improve the biosecurity management and diseases prevention of their farms. Totally, we had tested 652 shrimp and 875 environmental samples. The highest detection rate of above samples was 12.3% (188/1527) for EHP, followed by 2% (30/1527) for AHPND. According to the problems of farms encountered in this project, we suggest that the most important of building biosecurity for shrimp farms is the introduction of specific pathogen free (SPF) shrimp larvae to farms. Next, the shrimp pond should be cleaned and disinfected thoroughly before stocking seed; then, the material (food organisms, water and probiotics) should be free from the vibriosis contamination. Finally, biosecurity should be enforced to prevent irrelative people and animals from entering farms.

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