| Summary: | 碩士 === 國立成功大學 === 生物科技研究所碩博士班 === 96 === Grouper(Epinephelus coioides)is one of the economical fish in Taiwan. Because the virus infection in adult orange-spotted grouper is often light and unrecognized, grouper should have an efficient defense system against to nodaviruses. The defense system of interferon(IFN) in vertebrate provides an initial line of defense against viral infection by inducing the synthesis of proteins that inhibit virus replication. At least three different proteins mediate the antiviral response and one of them, Mx protein, specifically inhibits the replication of wide range of RNA virus has been well established. In the recent work, a homolog Mx (“OsgMx”) gene from orange-spotted grouper (Epinephelus coioides) had been cloned and sequenced. It contains an 1881 bp open reading frame region and encodes a protein with 626 amino acids. On protein structure, the grouper Mx protein is similar to the superfamily of large GTP-binding proteins. In this study, we transfected Mx-GFP and Mx-His fusion protein to GF1(grouper fin) cell line. Then we chose stable clones which can express Mx fusion proteins. We used MTT assay to observe the situation that the cell survives after NNV infection. Furthermore, we observed the NNV antigen expression and viral yields in cell lines after NNV infection. By the experimental results, we demonstrating that grouper Mx overexpression had an inhibitory effect on both coat protein and RNA dependent RNA polymerase (RdRp) of nodavirus antigens, resulting in reduced viral yields. We conclude that grouper Mx has a key role in cellular resistance to nodavirus infection. The antiviral activity through direct interaction, likely via the binding and perturbation of the intracellular localization of nodavirus coat protein.
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