An ShK-domain serine protease of Eriocheir sinensis regulates the PO activity to resist Spiroplasma eriocheiris infection

Current Disease Threats for Cultivated Crab Eriocheir sinensis in China

The Chinese mitten crab, Eriocheir sinensis, is a commercially important crustacean in China due to its great commercial value and compatibility in a variety of aquaculture systems. However, increases in its production have been accompanied by the emergence of various diseases affecting yield, profit, and trading potential. In this study, we review the pathogenic agents associated with E. sinensis since the start of its commercial culture. The history of crab cultivation implies that increased pathogen transfer can occur as E. sinensis aquaculture grows because polyculture of E. sinensis with other aquaculture species is a prevalent practice. With this in mind, a special focus of this review is placed on pathogens that were initially discovered in other crustacean species but have since been demonstrated to infect and cause disease in E. sinensis. We expect that this review will not only offer recommendations for disease management in the E. sinensis aquaculture sector but will also advance other crustacean cultivation.

Ubiquitin-modified proteome analysis of Eriocheir sinensis hemocytes during Spiroplasma eriocheiris infection

Spiroplasma eriocheiris, the pathogen of Eriocheir sinensis tremor disease (TD), has bring a huge economic loss to China aquaculture. The hemocytes of crab as the first target cells of S. eriocheiris, but the interactive relationship between the E. sinensis and this pathogen not particularly clear. The present study is the first time to analysis the role of protein ubiquitination in the process of E. sinensis hemocytes response S. eriocheiris infection. By applying label-free quantitative liquid chromatography with tandem mass spectrometry proteomics, 950 lysine ubiquitination sites and 803 ubiquitination peptides on 458 proteins were identified, of which 48 ubiquitination sites on 40 proteins were quantified as significantly changed after the S. eriocheiris infection. Bioinformatics analysis of ubiquitination different proteins suggested many biological process and pathways were participated in the interaction between S. eriocheiris and host cell, such as ubiquitin system, endocytosis, prophenoloxidase system (proPO system), cell apoptosis, glycolysis. Our study can enhance our understanding of interaction between the crab and S. eriocheiris, and also provides basis to study the role of protein ubiquitination in other crustacean innate immune system.

Effects of the interaction between a clip domain serine protease and a white spot syndrome virus protein on phenoloxidase activity

Clip domain serine proteinases participate in invertebrate innate immunity by acting as crucial enzymes in the signaling cascade involved in shrimp immunity. To functionally characterize its role in Fenneropenaeus merguiensis, FmclipSP cDNA was cloned and characterized. The FmclipSP gene comprised 1353 bp with an open reading frame of 1110 bp and encoded 369 amino acids. The protein contained clip and serine protease domains. FmClipSP mRNA is highly expressed in hemocytes, and its expression was significantly upregulated by bacterial or viral pathogen challenge. Furthermore, FmClipSP recombinant protein (rFmClipSP) was produced and possessed protease activity, stimulating prophenoloxidase activity. Additionally, rFmClipSP exhibited antibacterial activity against pathogens and nonpathogens. ELISA results demonstrated the binding ability of rFmClipSP to a recombinant protein of VP28 (rVP28). Interestingly, the binding significantly inhibited prophenoloxidase activity. Altogether, we partially characterized the function of FmclipSP and demonstrated its association with VP28. This study indicates the importance of clipSP as a component of F. merguiensis innate immunity. However, the role of clipSP in crustaceans remains unclear and requires further investigation.