Research on the indirect antiviral function of medicinal plant ingredient quercetin against grouper iridovirus infection

Akt inhibitors prevent CyHV-2 infection in vitro

Cyprinid herpesvirus 2 (CyHV-2) is a double-stranded DNA virus that infects goldfish (Carassius auratus) and crucian carp (C. carassius), resulting in substantial mortality rates and significant epidemiological implications. To gain deeper insights into CyHV-2-host interactions and identify potential therapeutic targets, quantitative proteomics analysis was conducted on CyHV-2-infected Ryukin goldfish fin (RyuF-2) cells. Our findings revealed significant alterations in the expression of proteins associated with the PI3K/Akt signaling pathway, which were up-regulated upon viral infection. Building on these observations, we employed LY294002, a specific inhibitor of PI3K, to investigate its impact on viral replication by inhibiting the PI3K/Akt pathway in GiCF cell line derived from the caudal fin of Carassius auratus gibelio (Bloch). Our results demonstrated the inhibition of both CyHV-2 replication and Akt phosphorylation within this pathway. Quercetin, a plant-derived analogue of LY294002, was further investigated for its anti-CyHV-2 effects in vitro as well as its underlying mechanism. The results suggested that quercetin exhibits antiviral properties against CyHV-2 and may exert its effects through mechanisms similar to those observed with LY294002. Given that aquaculture water serves as a vector for aquaculture viral diseases and the release of chemical compounds can lead to pollution of the aquatic environment, our study shifted focus to crude extracts obtained from plants. We confirmed crude quercetin extract derived from Cuminum anisum has antiviral activity against CyHV-2 in vitro. Therefore, based on our identification of the involvement of PI3K/Akt signaling pathway in CyHV-2 replication, along with verification of its antiviral mechanism using LY294002, we propose natural dietary quercetin as a promising candidate for development into a novel anti-CyHV-2 drug.

Palmatine as a potent immunomodulator: Enhancing resistance to Micropterus salmoides rhabdovirus in largemouth bass through innate immune activation and viral suppression

Micropterus salmoides rhabdovirus (MSRV) poses a significant threat to aquaculture, causing substantial economic losses. In this study, we evaluated the antiviral efficacy and immunomodulatory potential of palmatine, a plant-derived monomer, against MSRV infection in largemouth bass. Our results demonstrated that palmatine significantly inhibited MSRV replication, with a reduction in viral nucleoprotein expression by 85 % at a safe concentration. Additionally, palmatine pre-treatment of EPC cells enhanced their antiviral capacity, with a maximum inhibition rate of 82 % following 24 h pre-incubation. Palmatine also effectively reduced MSRV-induced cytopathic effects, protecting cellular integrity and maintaining mitochondrial membrane potential. In vivo studies revealed that palmatine immersion at 80 mg/L was non-toxic and significantly suppressed MSRV replication in largemouth bass, increasing survival rates by 53 % over 15 d. Furthermore, palmatine pre-treatment enhanced the fish's resistance to MSRV, with a 78 % inhibition rate of viral replication and a 46 % increase in survival rate. Mechanistically, palmatine activated key immune genes, including IRF3, IRF7, and IFN, indicating its role in boosting innate immune responses. The compound also reduced horizontal transmission of MSRV in a cohabitation model, decreasing viral spread by up to 78 % over nine days. These findings highlight palmatine's potential as a small-molecule immunomodulator in aquaculture, offering a sustainable approach to disease management and enhancing fish health and welfare. Integrating palmatine into fish diets as an immunostimulant could provide a continuous, proactive defense against viral outbreaks, promoting more resilient and sustainable aquaculture practices.

In vitro antiviral activity of eugenol on Singapore grouper iridovirus

The high mortality rate of Singapore grouper iridovirus (SGIV) posing a serious threat to the grouper aquaculture industry and causing significant economic losses. Therefore, finding effective drugs against SGIV is of great significance. Eugenol (C10H12O2) is a phenolic aromatic compound, has been widely studied for its anti-inflammatory, antioxidant and antiviral capacity. In this study, we explored the effect of eugenol on SGIV infection and its possible mechanisms using grouper spleen cells (GS) as an in vitro model. We found that treatment of GS cells with 100 μM eugenol for 4 h exhibited the optimal inhibitory effect on SGIV. Eugenol was able to reduce the expression level of inflammatory factors by inhibiting the activation of MAPK pathway and also inhibited the activity of NF-κB and AP-1 promoter. On the other hand, eugenol attenuated cellular oxidative stress by reducing intracellular ROS and promoted the expression of interferon-related genes. Therefore, we conclude that eugenol inhibits SGIV infection by enhancing cellular immunity through its anti-inflammatory and antioxidant functions.

The combined analysis of transcriptomics and metabolomics reveals the mechanisms by which dietary quercetin regulates growth and immunity in Penaeus vannamei

As a potent antioxidant, the flavonoid compound quercetin (QUE) has been widely used in the farming of aquatic animals. However, there are fewer reports of the beneficial effects, especially in improving immunity of Penaeus vannamei by QUE. The aim of this study was to investigate the effects of dietary QUE on growth, apoptosis, antioxidant and immunity of P. vannamei. It also explored the potential mechanisms of QUE in improving the growth and immunity of P. vannamei. P. vannamei were fed diets with QUE for 60 days. The results revealed that QUE (0.5 or 1.0 g/kg) ameliorated the growth, and the expressions of genes related to apoptosis, antioxidant, and immunity. The differentially expressed genes (DEGs) and differential metabolites (DMs) obtained through transcriptomics and metabolomics, respectively, enriched in pathways related to nutritional metabolism such as lipid metabolism, amino acid metabolism, and carbohydrate metabolism. After QUE addition, especially at 0.5 g/kg, DEGs were enriched into the functions of response to stimulus and antioxidant activity, and the pathways of HIF-1 signaling pathway, C-type lectin receptor signaling pathway, Toll-like receptor signaling pathway, and FoxO signaling pathway. In conclusion, dietary QUE can ameliorate growth, apoptosis, antioxidant and immunity of P. vannamei, the appropriate addition amount was 0.5 g/kg rather than 1.0 g/kg. Regulations of QUE on nutrient metabolism and immune-related pathways, and bioactive metabolites, were important factors for improving the aforementioned abilities in P. vannamei.

Phenotypic characteristics and immune response of Procypris merus following challenge with aquatic isolate of Klebsiella pneumoniae

Currently, aquaculture is a relatively mature industry; however, disease problems are continuously threatening the industry and hindering its development to a certain extent. Klebsiella pneumoniae is one of the zoonotic bacteria widely present in different hosts and has caused some degree of harm to the aquaculture industry, posing a potential threat to the water environment and indirectly also affecting human food safety issues. In this study, K. pneumoniae was isolated from the aquaculture environment, named as ELD, and subjected to pathogenic and immunological related studies. The results of the study showed that the strain carries at least four virulence-related genes, magA, wabG, ureA and uge, and has developed resistance to at least seven antibacterial drugs, such as amoxicillin, doxycycline, rifampicin, and so on. Moreover, the strain is highly pathogenic and is capable of causing systemic clinical foci in Procypris merus. In addition, after infection with K. pneumoniae, the expression of IL-1β, IL-8, HSP70 and C2 was upregulated in P. merus as a whole, whereas the expression of TNF-α did not change significantly in any of the tissues, which might be a kind of immune response of P. merus against K. pneumoniae infection. This study provides an important theoretical basis for the in-depth exploration of the pathogenic mechanism of K. pneumoniae in fish and the immune response that occurs after the disease is contracted in fish, as well as theoretical support for the development of effective preventive and therapeutic strategies against K. pneumoniae-infected aquatic animals in the future.

Molecular and functional characterization of viperin in golden pompano, Trachinotus ovatus

The radical S-adenosyl methionine domain-containing protein 2 (RSAD2), also known as viperin, plays a momentous and multifaceted role in antiviral immunity. However, the function of viperin is uninvestigated in golden pompano, Trachinotus ovatus. In the present study, a viperin homolog, named To-viperin, was cloned and characterized from golden pompano, and its role in response to grouper iridovirus (SGIV) and nervous necrosis virus (NNV) infection was investigated. The whole open reading frame (ORF) of To-viperin was composed of 1050 bp and encoded a polypeptide of 349 amino acids with 70.66%-83.51% identity with the known viperin homologs from other fish species. A variable N-terminal domain, a highly conserved C-terminal domain, and a conserved middle radical SAM domain (aa 61-271) with the three-cysteine motif CxxCxxC was found in To-viperin sequence. Expression analysis showed that To-viperin was constitutively expressed in all tested organs and was located mainly in the ER of golden pompano cells. Treatments with SGIV, poly I: C, or NNV could induce the up-regulation of viperin to varying degrees. The ectopic expression of To-viperin in vitro significantly reduced the viral titer of SGIV and NNV. Furthermore, To-viperin overexpression enhanced the expression of IFNc, IRF3, and ISG15 genes as well as, to a lesser extent, the IL-6 gene. In summary, our results suggested that the function of viperin is likely to be conserved in fish specise, as observed in other vertebrates, shedding light on the evolutionary conservation of viperin.

Discovery of therapeutic targets of quercetin for endometrial carcinoma patients infected with COVID-19 through network pharmacology

Purpose

Aimed to identify the anti-uterine corpus endometrial carcinoma (UCEC) function and characterize the mechanism of quercetin in the treatment of patients infected with COVID-19 via integrated in silico analysis.

Methods

The Cancer Genome Atlas and Genotype Tissue Expression databases were applied to obtain differentially expressed genes of UCEC and non-tumor tissue. Several in silico methods such as network pharmacology, functional enrichment analysis, Cox regression analyses, somatic mutation analysis, immune infiltration and molecular docking were used to investigate and analysis the biological targets, functions and mechanisms of anti-UCEC/COVID-19 of quercetin. Multiple methods such as CCK8 assay, Transwell assay and western blotting were performed to test proliferation, migration, and protein level of UCEC (HEC-1 and Ishikawa) cells.

Results

Functional analysis disclosed that quercetin against UCEC/COVID-19 mainly by ‘biological regulation’, ‘response to stimulus’, and ‘regulation of cellular process’. Then, regression analyses indicated that 9 prognostic genes (including ANPEP, OAS1, SCGB1A1, HLA‐A, NPPB, FGB, CCL2, TLR4, and SERPINE1) might play important roles in quercetin for treating UCEC/COVID-19. Molecular docking analysis revealed that the protein products of 9 prognostic genes were the important anti-UCEC/COVID-19 biological targets of quercetin. Meanwhile, the proliferation and migration of UCEC cells were inhibited by quercetin. Moreover, after treatment with quercetin, the protein level of ubiquitination-related gene ISG15 was decreased in UCEC cells in vitro.

Conclusions

Taken together, this study provides new treatment option for UCEC patients infected with COVID-19. Quercetin may work by reducing the expression of ISG15 and participating in ubiquitination-related pathways.

Quercetin Application for Common Carp (Cyprinus carpio): I. Effects on Growth Performance, Humoral Immunity, Antioxidant Status, Immune-Related Genes, and Resistance against Heat Stress

This study was done to evaluate the effect of different quercetin levels on growth performance, immune responses, antioxidant status, serum biochemical factors, and high-temperature stress responses in common carp (Cyprinus carpio). A total number of 216 common carp with an average weight of 27.21 ± 53 g were divided into 12 tanks (four treatments × three replications) and fed 0 mg/kg quercetin (T0), 200 mg/kg quercetin (T1), 400 mg/kg quercetin (T2), and 600 mg/kg quercetin (T3) for 60 days. There were significant differences in growth performance, and the highest final body weight (FBW), weight gain (WG), specific growth rate (SGR), and feed intake (FI) were observed in T2 and T3 (P < 0.05). Different quercetin levels significantly increased complement pathway activity (ACH50) and lysozyme activity both before and after heat stress (P < 0.05). Catalase (CAT), glutathione peroxidase (GPx), and malondialdehyde (MDA) were significantly increased in fish exposed to heat stress, but fish fed with a supplemented diet with quercetin showed the lowest levels both before and after heat stress (P < 0.05). Superoxide dismutase (SOD) levels were significantly enhanced in fish fed diets supplemented with quercetin in both phases (P < 0.05). Different quercetin levels led to a significant decrease in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) before and after the challenging test (P < 0.05). Glucose and cortisol levels were significantly higher in the control group compared to the other treatments in both phases (P < 0.05). The expression of glutathione peroxidase (GPx) and lysozyme was markedly upregulated in fish fed with quercetin-supplemented diets (P < 0.05). No marked effects were observed for growth hormone (GR) and interleukin-8 (IL8) (P > 0.05). In conclusion, dietary quercetin supplementations (400-600 mg/kg quercetin) improved growth performance, immunity, and antioxidant status and increased tolerance to heat stress.

Identification of ISG15 in golden pompano, Trachinotus ovatus, and its role in virus and bacteria infections

Interferon (IFN)-stimulated gene product 15 (ISG15) is a ubiquitin-like protein critical for the control of microbial infections. Golden pompano, Trachinotus ovatus is one of the precious marine economic fish in the southern coast of China, always suffering from viruses, bacteria, and parasite infections. To date, the roles of golden pompano genes involved in viral and bacterial infections, especially IFN-related genes remained largely unknown. To identify the interferon system genes of golden pompano and explore their function, in this study, the ISG15 homolog (ToISG15) was cloned from golden pompano, and its role in response to grouper iridovirus (SGIV), nervous necrosis virus (NNV), and Aeromonas hydrophila infection was investigated. The whole ORF of ToISG15 was composed of 465 bp and encoded a polypeptide of 154 amino acids with different identity with the known ISG15 homologs from other fish species. Two conserved ubiquitin-like (UBL) domains and an Ub-conjugation domain (LRGG) were found in ToISG15 sequence. Expression analysis showed that ToISG15 was located mainly in the cytoplasm of golden pompano cells, and dramatically induced following SGIV, Aeromonas hydrophila, or poly I:C treatment, but little change was observed when NNV infection. Overexpression of ToISG15 in vitro significantly inhibited the replication of SGIV and NNV. Interestingly, ToISG15 possessed the ability to restrain the growth of Aeromonas hydrophila. Furthermore, To-ISG15 overexpression enhanced the expression of IFNc, IFNh, IRF3, IRF7, and viperin genes as well as, to a lesser extent, the IL-6 gene. Taken together, our results demonstrated the antiviral and antibacterial effect of To-ISG15, shedding light on the evolutionary conservation of ISG15 in the immune response to microbial infection.

Review of Medicinal Plants and Active Pharmaceutical Ingredients against Aquatic Pathogenic Viruses

Aquaculture offers a promising source of economic and healthy protein for human consumption, which can improve wellbeing. Viral diseases are the most serious type of diseases affecting aquatic animals and a major obstacle to the development of the aquaculture industry. In the background of antibiotic-free farming, the development and application of antibiotic alternatives has become one of the most important issues in aquaculture. In recent years, many medicinal plants and their active pharmaceutical ingredients have been found to be effective in the treatment and prevention of viral diseases in aquatic animals. Compared with chemical drugs and antibiotics, medicinal plants have fewer side-effects, produce little drug resistance, and exhibit low toxicity to the water environment. Most medicinal plants can effectively improve the growth performance of aquatic animals; thus, they are becoming increasingly valued and widely used in aquaculture. The present review summarizes the promising antiviral activities of medicinal plants and their active pharmaceutical ingredients against aquatic viruses. Furthermore, it also explains their possible mechanisms of action and possible implications in the prevention or treatment of viral diseases in aquaculture. This article could lay the foundation for the future development of harmless drugs for the prevention and control of viral disease outbreaks in aquaculture.