Small Molecule Inhibitors of White Spot Syndrome Virus: Promise in Shrimp Seedling Culture

Rhein: A potent immunomodulator empowering largemouth bass against MSRV infection

Micropterus salmoides rhabdovirus (MSRV) is a significant viral pathogen in largemouth bass aquaculture, causing substantial annual economic losses. However, effective prevention methods remain elusive for various reasons. Medicinal plant extracts have emerged as valuable tools in preventing and managing aquatic animal diseases. Thus, the search for immunomodulators with straightforward, safe structures in plant extracts is imperative to ensure the continued health and growth of the largemouth bass industry. In our research, we employed epithelioma papulosum cyprinid (EPC) cells and largemouth bass as models to assess the anti-MSRV properties and immunomodulatory effects of ten plant-derived bioactive compounds. Among them, rhein demonstrated noteworthy potential, exhibiting a 75 % reduction in viral replication in vitro at a concentration of 50 mg/L. Furthermore, rhein pre-treatment significantly inhibited MSRV genome replication in EPC cells, with the highest inhibition rate reaching 64.8 % after 24 h, underscoring rhein's preventive impact against MSRV. Likewise, rhein displayed remarkable therapeutic effects on EPC cells during the early stages of MSRV infection, achieving a maximum inhibition rate of 85.6 % in viral replication. Subsequent investigations unveiled that rhein, with its consistent activity, effectively mitigated cytopathic effects (CPE) and nuclear damage induced by MSRV infection. Moreover, it restrained mitochondrial membrane depolarization and reduced the apoptosis rate by 38.8 %. In vivo experiments reinforced these findings, demonstrating that intraperitoneal injection of rhein enhanced the expression levels of immune related genes in multiple organs, hindered virus replication, and curtailed the mortality rate of MSRV-infected largemouth bass by 29 %. Collectively, our study endorses the utility of rhein as an immunomodulator to combat MSRV infections in largemouth bass. This not only underscores the potential of rhein as a broad-spectrum antiviral and means to bolster the immune response but also highlights the role of apoptosis as an immunological marker, making it an invaluable addition to the armamentarium against aquatic viral pathogens.

Antiviral, antioxidant, and anti-inflammatory activities of rhein against white spot syndrome virus infection in red swamp crayfish (Procambarus clarkii)

IMPORTANCE

Aquaculture is essential for ensuring global food security by providing a significant source of animal protein. However, the spread of the white spot syndrome virus (WSSV) has resulted in considerable economic losses in crustacean industries. In this study, we evaluated the antiviral activity of rhein, the primary bioactive component of Rheum palmatum L., against WSSV infection, and many pathological aspects of WSSV were also described for the first time. Our mechanistic studies indicated that rhein effectively arrested the replication of WSSV in crayfish by modulating innate immunity to inhibit viral gene transcription. Furthermore, we observed that rhein attenuated WSSV-induced oxidative and inflammatory stresses by regulating the expression of antioxidant and anti-inflammatory-related genes while enhancing innate immunity by reducing total protein levels and increasing phosphatase activity. Our findings suggest that rhein holds great promise as a potent antiviral agent for the prevention and treatment of WSSV in aquaculture.

Herbal active small molecule as an immunomodulator for potential application on resistance of common carp against SVCV infection

Herbal immunomodulators are an important part of prevention and control on viral diseases in aquaculture because of their propensity to improve immunity in fish. The present study was conducted to evaluate the immunomodulatory effect and antiviral activity of a synthesized derivative (serial number: LML1022) against spring viremia of carp virus (SVCV) infection in vitro and in vivo. The antiviral data suggested that LML1022 at 100 μM significantly inhibited the virus replication in epithelioma papulosum cyprini (EPC) cells, and may completely inhibit the infectivity of SVCV virion particles to fish cells by affecting the viral internalization. The results in the related stability of water environments also demonstrated that LML1022 had an inhibitory half-life of 2.3 d at 15 °C, which would facilitate rapid degradation of LML1022 in aquaculture application. For in vivo study, the survival rate of SVCV-infected common carp was increased 30% at least under continuous oral injection of LML1022 at 2.0 mg/kg for 7 d treatment. Additionally, pretreatment of LML1022 on fish prior to SVCV infection also obviously reduced the viral loads in vivo as well as an improved survival rate, showing that LML1022 was potential as an immunomodulator. As an immune response, LML1022 significantly upregulated the immune-related gene expression including IFN-γ2b, IFN-I, ISG15 and Mx1, indicating that its dietary administration may improve the resistance of common carp against SVCV infection.

A novel neural network model for shrimp segmentation to detect white spot syndrome

Image segmentation is an essential part of almost any image processing methodology and it play a critical role in protecting the region of interest on any substrate image before its actual analysis is prescribed. In fact, the accuracy of any processing done by image segmentation will largely depends on the efficiency of the segmentation algorithm employed. A typical segmentation method employing a important features of Canny–GLCM (Gray Level Co-occurrence Matrix) incorporated with a simple Artificial Neural Network (ANN) model is proposed in this research work for segmentation of shrimp variability. Performance metrics related to accuracy have been compared with benchmark of this method, and the sensitivity of efficiency level has been described. The segmentation in the proposed research work is targeted towards Penaeus Monodon (PM), and Litopenaeus Vannamei (LV) diversities for main threats detection of White Spot Syndrome (WSS). The proposed model has better performance metrics, such as (94.67%), sensitivity (94.79%), specificity (94.51%) and positive predictive (94.79%) while compared to other existing methods.

Natural ingredient paeoniflorin could be a lead compound against white spot syndrome virus infection in Litopenaeus vannamei

White spot syndrome virus (WSSV) is an important pathogen causing high mortality in the shrimp industry in aquaculture, yet there is no treatment available to date. In order to find a treatment against WSSV infection, this study examined the anti-WSSV activity of eight natural compounds using shrimp larvae as a model. Among the eight compounds, paeoniflorin showed the most obvious anti-WSSV effect, with a maximum protection efficiency of WSSV-infected shrimp >60% at 100 μM. Furthermore, pretreatment and post-treatment experiments revealed that paeoniflorin could prevent and treat WSSV infection in shrimp. The antiviral activity of paeoniflorin in aquaculture water decreased rapidly with time, and the results showed that the stable anti-WSSV activity of paeoniflorin could only remain in water for 1 day. Thus, the dosing pattern of continuous medication changes was evaluated. Obviously, in the model of continuous change of paeoniflorin, WSSV copy numbers in the virus-treated shrimp group still progressively increased, while the virus content in WSSV_paeoniflorin -treated group continued to decrease. Interestingly, paeoniflorin inhibited horizontal transmission of WSSV to a certain extent. Notably, paeoniflorin significantly increased the expression of antimicrobial peptides of shrimp to resist WSSV. In conclusion, paeoniflorin has the potential to protect shrimp against WSSV.