碩士 / 國立臺灣大學 / 漁業科學研究所 / 105 / Shrimp farming is an important part of aquaculture industry, with output value reaching 22 billion U.S. dollar annually. However, pathogens always devastate shrimp farming, causing enormous economic losses. White spot disease (WSD) is one of the most potent and widespread disease, with the typical syndrome white spots on the cuticle of the shrimp cephalothorax, carapace and appendage. WSD can cause up to 90-100% mortality within 10 days after symptoms appear. WSD is caused by white spot syndrome virus (WSSV). More than 40 viral proteins of WSSV were identified and studied, including structural and non-structural proteins. One of them, VP28, is a major envelope protein of WSSV, may play an important role in the infection process of WSD.
WSD has been found for more than 20 years, but there are still no available treatment measures. Transcending Biotechnologies Inc. (U.S.A.) developed a monoclonal antibody, AP-1. AP-1 can bind to VP28 tightly and interfere the interaction between WSSV and host cell, thus preventing shrimp from infection of WSSV. However, the production cost of monoclonal antibody is too high to be practically utilized for shrimp farming. The variable fragment of AP-1, which contains complete antigen-binding site, was synthesized as the single chain peptide, sAP-1. sAP-1 was successfully expressed in huge quantity by E. coli expression system. However, previous studies found that the anti-WSSV activity of monomeric sAP-1 is weaker than that of the dimeric AP-1. We speculate that AP-1 with two antigen-binding site may bind to VP28 more tightly than sAP-1 with only one antigen-binding site, thus AP-1 has stronger anti-WSSV ability.
For those reasons, this study aims to modify sAP-1 by adding leucine zipper after its C-terminus, making two sAP-1 monomers forming dimmer, dsAP-1. The anti-WSSV efficacy of ds-AP-1 is proposed to be improved. The dsAP-1 may be used at large scale shrimp farming to prevent WSSV infection.
The result of ELISA showed that the WSSV binding ability of dsAP-1 was slightly better than that of sAP-1. WSSV viral challenge also showed that the survival rate of dsAP-1 group was better than sAP-1 group at the same amount of protein. The dimerized sAP-1 has better anti-WSSV activity than sAP-1.
| Identifer | oai:union.ndltd.org:TW/105NTU05451014 |
| Date | January 2017 |
| Creators | Chung- San Lee, 李鍾山 |
| Contributors | 韓玉山 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | en_US |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 65 |
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