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Hybrid groupers become one of the important aquatic animals, but gastric pathogen infection causes losses due to Vibrio sp. infections. Ethyl caffeate (EC), a naturally occurring antioxidant and antibacterial derived from medicinal plant. This study investigated the effects of EC on the immune response, growth performance, as well as the systemic and mucosal immunity following Vibrio parahaemolyticus challenge. The hybrid groupers were fed diets containing EC at the concentrations of 0, 0.1, 0.25, and 0.5 g/kg (control, EC0.1, EC0.25, and EC0.5 groups, respectively). This feeding trial was conducted in three-part separate experiments consist of non-specific immune response, growth performance and challenge test experiment. The result demonstrated that the EC0.25 group had the highest total leukocyte count, phagocytic activity, and respiratory burst (O 2 - ) and the highest upregulation of genes related to antioxidant activity, inflammation, antimicrobial peptides, and stress. Furthermore, higher growth performance was observed in all EC groups than in the control group with the EC0.25 group exhibited optimum growth performance. According to the challenge test results, the EC0.25 group exhibited strong resistance to V. parahaemolyticus, with a survival rate of 96.7 %. This study elucidated a novel self-defense mechanism after EC modulating against V. parahaemolyticus challenge in hybrid groupers. The EC0.25 group had increased leukocyte subpopulation and the highest upregulation of Toll-like receptor 4, Toll-like receptor 21, MyD88, major histocompatibility complex II, immunoglobulin M, interleukin-1β, and tumor necrosis factor-α in both systemic and mucosal related-organs. Overall, dietary EC0.25 increased the hybrid groupers health status, activated multiple signaling pathways, and synergistically increased the host's systemic and mucosal immunity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2025. Published by Elsevier Ltd.)

Plantago asiatica seeds (PS) are commonly used as a medicinal plant. This study investigates the efficacy of PS against heavy metal toxicity in white shrimp (Penaeus vannamei). After feeding PS diet (5 g/kg) or basal diet (control group) for 7 days, shrimps were exposed to sublethal concentrations of heavy metals in seawater (As: 12 mg/L, Pb: 250 mg/L, Hg: 0.4 mg/L). The 7-day survival observation showed that the survival in groups fed with PS were significantly higher than that in the control group, revealing that dietary PS had the efficacy to mitigate heavy metal toxicity in white shrimp. Under the same feeding condition, white shrimps were exposed to safety dose of heavy metals (1/10 of sublethal concentrations) to understand the mechanism of mitigation. The metal accumulations in haemolymph, gills, hepatopancreas, and muscle tissues as well as the immune, anti-oxidative, stress related gene expressions in haemocytes, gills and hepatopancreas were measured for 14 days. The As accumulation in gills and hepatopancreas of groups fed with PS were significantly lower than those of control group on day 7 and 14, respectively; The Pb concentration in haemolymph of group fed with PS was significantly lower than that of control group on day 7 and 14; The Hg concentration in hepatopancreas of the group fed with PS was significantly lower than that of control group on day 7. Dietary PS could mitigate heavy metal-induced immune suppression, oxidative stress, and stress response by positively regulating immune (proPO I, Toll, IMD), antioxidant (SOD, GST, Trx), and negatively regulating stress response genes (HSP70, MT). The present study demonstrated that dietary PS could protect white shrimp against metal toxicity by reducing metal accumulations and regulating the immune, antioxidant, and stress response gene expressions in specific tissue. Therefore, PS may serve as a beneficial feed additive in the aquaculture., Competing Interests: Declaration of competing interest No conflicts of interest are declared., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

This study investigated the effects of Cinnamomum osmophloeum leaf hot-water extract (CLWE) on nonspecific immune responses and resistance to Vibrio parahaemolyticus in white shrimp (Penaeus vannamei). Firstly, a cell viability assay demonstrated that the CLWE is safe to white shrimp heamocytes in the concentration of 0-500 mg L -1 . Haemocytes incubated in vitro with 10 and 50 mg L -1 of CLWE showed significantly higher response in superoxide anion production, PO activity, and phagocytic activity. In the in vivo trials, white shrimp were fed with 0, 0.5, 1, 5, and 10 g kg -1 CLWE supplemented feeds (designated as CLWE 0, CLWE 0.5, CLWE 1, CLWE 5, and CLWE 10, respectively) over a period of 28 days. In vivo experiments demonstrated that CLWE 0.5 feeding group resulted in the highest total haemocyte count, superoxide anion production, phenoloxidase activity, and phagocytic activity. Moreover, CLWE 0.5 supplemented feed significantly upregulated the clotting system, antimicrobial peptides, pattern recognition receptors, pattern recognition proteins, and antioxidant defences in white shrimp. Furthermore, the shrimp were infected with V. parahaemolyticus injections after 14 days of feeding as challenge test. Based on the challenge test result, both CLWE 0.5 and CLWE 5 demonstrated a strong resistance to V. parahaemolyticus. These two dosages effectively reduced the number of nonviable cells and activated different haemocyte subpopulations. These findings indicated that treatment with CLWE 0.5 could promote nonspecific immune responses, immune-related gene expression, and resistance to V. parahaemolyticus in white shrimp., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Hybrid of nanosilver and nanoscale silicate platelet (AgNSP) is a safe, non-toxic nanomaterial which has been applied in medical use due to its strong antibacterial activity. The application of AgNSP in aquaculture was first proposed in the present study by evaluating the in vitro antibacterial activities against four aquatic pathogens, in vitro effects toward shrimp haemocytes as well as the immune responses and disease resistance in Penaeus vannamei fed with AgNSP for 7 days. For evaluating the antibacterial activities of AgNSP in culture medium, the minimum bactericidal concentration (MBC) values against Aeromonas hydrophila, Edwardsiella tarda, Vibrio alginolyticus and Vibrio parahaemolyticus were 100, 15, 625 and 625 mg/L, respectively. Moreover, the inhibition of pathogen growth over a period of 48 h could be achieved by the appropriate treatment of AgNSP in culturing water. In freshwater containing bacterial size of 10 3 and 10 6  CFU/mL, the effective doses of AgNSP against A. hydrophila were 12.5 and 450 mg/L, respectively while the effective doses against E. tarda were 0.2 and 50 mg/L, respectively. In seawater with same bacterial size, the effective doses against V. alginolyticus were 150 and 2000 mg/L, respectively while the effective doses against V. parahaemolyticus were 40 and 1500 mg/L, respectively. For the in vitro immune tests, the superoxide anion production and phenoloxidase activity in haemocytes were elevated after in vitro incubation with 0.5-10 mg/L of AgNSP. In the assessment of dietary supplemental effects of AgNSP (2 g/kg), no negative effect on the survival was found at the end of 7 day feeding trail. In addition, the gene expression of superoxide dismutase, lysozyme and glutathione peroxidase were up-regulated in haemocytes taken from shrimps received AgNSP. The following challenge test against Vibrio alginolyticus showed that the survival of shrimp fed with AgNSP was higher than that of shrimp fed with control diet (p = 0.083). Dietary AgNSP improved the Vibrio resistance of shrimp by increasing 22.7% of survival rate. Therefore, AgNSP could potentially be used as a feed additive in shrimp culture., Competing Interests: Declaration of competing interest No conflicts of interest are declared., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Lactobacillus plantarum is known for its probiotics benefit to host, although the effects vary among strains. This study conducted a feeding experiment of three Lactobacillus strains, MRS8, MRS18 and MRS20, which were isolated from kefir and incorporated into the diets of shrimp to evaluate the effects of non-specific immunity, immune-related gene expression, and disease resistance of white shrimp (Penaeus vannamei) against Vibrio alginolyticus. To prepare the experimental feed groups, the basic feed was mixed with different concentrations of L. plantarum strains MRS8, MRS18, and MRS 20, which were incorporated at 0 CFU (control), 1 × 10 6  CFU (groups 8-6, 18-6, and 20-6), and 1 × 10 9  CFU (groups 8-9, 18-9, and 20-9) per gram of diet for an in vivo assay. During the rearing period for 28 days of feeding each group, immune responses, namely the total hemocyte count (THC), phagocytic rate (PR), phenoloxidase activity, and respiratory burst were examined on days 0, 1, 4, 7, 14, and 28. The results showed that groups 20-6, 18-9 and 20-9 improved THC, and groups 18-9 and 20-9 improved phenoloxidase activity and respiratory burst as well. The expression of immunity-related genes was also examined. Group 8-9 increased the expression of LGBP, penaeidin 2 (PEN2) and CP, group 18-9 increased the expression of proPO1, ALF, Lysozyme, penaeidin 3 (PEN3) and SOD, and group 20-9 increased the expression of LGBP, ALF, crustin, PEN2, PEN3, penaeidin 4 (PEN4) and CP (p < 0.05). Groups 18-6, 18-9, 2-6, and 20-9 were further used in the challenge test. After feeding for 7 days and 14 days, Vibrio alginolyticus was injected into white shrimp and observed the shrimp survival for 168 h. The results showed that compared to the control, all groups improved the survival rate. Especially, feeding group 18-9 for 14 days improved the survival rate of white shrimp (p < 0.05). After the challenge test for 14 days, the midgut DNA of survival white shrimps was extracted to analyze the colonization of L. plantarum. Among the groups, (6.61 ± 3.58) × 10 5  CFU/pre shrimp of L. plantarum in feeding group 18-9 and (5.86 ± 2.27) × 10 5  CFU/pre shrimp in group 20-9 were evaluated by qPCR. Taken together, group 18-9 had the best effects on the non-specific immunity, the immune-related gene expression, and the disease resistance, which might be due to the benefit of the probiotic colonization., Competing Interests: Declaration of competing interest The authors declare no competing financial interests or personal relationships that could have influenced the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

This study investigated the effects of two probiotics, namely Lactobacillus paracasei and Bifidobacterium longum, as feed additives on growth performance, nonspecific immunity, immune-related gene expression, and disease resistance against Vibrio parahaemolyticus in Penaeus vannamei. The experimental diets were prepared using L. paracasei and B. longum at concentrations of 10 5 and 10 7  CFU/g; these diets were referred to as P5, P7, B5, and B7. After 8 weeks of the diets, regarding growth performance, the B7 group showed the highest weight gain rate (890.34 ± 103.65%), special growth rate (4.08 ± 0.19%), and feed conversion rate (1.52 ± 0.19%) compared with the other groups. Moreover, the total hemocyte counts were significantly increased (p < 0.05) in the P7 groups on day 14 during the 28-day feeding trial. The phagocytosis rate in all experimental groups was increased on day 14 and was persistently significantly activated to day 21, especially in the P7 and B5 group. The phagocytic index of the P7 group showed a significant increase on day 14 and persistent activation to day 21. In the analysis of respiratory burst activity and phenoloxidase activity, the P7 and B5 groups showed a significant increase on day 7 and persistent activation to day 21. The expression level of the immune-related genes of superoxide dismutase, clotting protein, Penaeidin2, Penaeidin3, Penaeidin4, anti-LPS factor, crustin, and lysozyme was significantly increased in the experimental groups, especially in the P7 group. Furthermore, the optimum conditions of feed additives were determined in challenge trials conducted using P7 and B5. Shrimps fed P7 and B5 showed an increased survival rate (72.73% and 66.67%) after the V. parahaemolyticus challenge. In sum, the results revealed that B. longum, as a feed additive at 10 7  CFU/g, enhanced growth performance. L. paracasei at 10 7  CFU/g and B. longum at 10 5  CFU/g can enhance nonspecific immune responses and immune-related gene expression, and 10 7  CFU/g L. paracasei has the highest resistance ability for V. parahaemolyticus. Thus, dietary supplementation with L. paracasei and B. longum may be a valuable approach in white shrimp aquaculture., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study investigated the synergistic effects of oxolinic acid (OA) combined with oxytetracycline (OTC) on white shrimp (Penaeus vannamei). Disk diffusion susceptibility testing was performed to analyze the sensitivity of Vibrio alginolyticus and Vibrio parahaemolyticus to different concentrations of OA and OTC. The results revealed that 50 mg OA/L combined with 50 mg OTC/L exhibited stronger antibacterial effects on V. alginolyticus and V. parahaemolyticus. The results of in vitro tests indicated that cotreatment with OA and OTC significantly reduced superoxide anion production and phenoloxidase activity, but not phagocytic activity. Subsequently, feeding trials were performed to investigate the immunomodulatory effects and bioaccumulation of dietary OA combined with OTC on shrimp. The healthy shrimp (15.13 ± 1.02 g) were divided into four groups: control, 100 mg OA/kg combined with 50 mg OTC/kg, 50 mg OA/kg combined with 100 mg OTC/kg, and 50 mg OA/kg combined with 50 mg OTC/kg. The shrimp were sampled to determine innate immunity parameters and residual OA and OTC levels in the muscle during a 28-day feeding regimen; the shrimp were fed the experimental diet from day 1 to day 5 and a commercial diet from day 6 to day 28. Residual OA levels were considerably higher in the group fed 100 mg OA/kg combined with 50 mg OTC/kg compared with the other groups and peaked on day 4. The residual OA levels of all the groups were below the detection limit after without providing OA. The residual OTC levels of the group fed 50 mg OA/kg combined with 100 mg OTC/kg were considerably higher from day 1 to day 4. The residual OTC levels in all the groups decreased rapidly and could not be detected on day 28. The administration of 50 mg OA/kg combined with 100 mg OTC/kg exerted the least effect on the white shrimp. Moreover, the survival rates of the treatment groups after the V. parahaemolyticus challenge were higher than those of the control group, especially the group fed 50 mg OA/kg combined with 100 mg OTC/kg. This result indicated that the synergistic effects of dietary OA and OTC are safe and effective. Combination therapy is a new method of antibiotic use in aquaculture., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study investigated the effect of the moringa (Moringa oleifera) leaf extract and Lactobacillus acidophilus individually or combined on growth performance, enzyme activity, intestinal and hepatopancreatic histology, intestinal microbiota, immune response, and resistance against Vibrio alginolyticus and Vibrio parahaemolyticus in whiteleg shrimp (Penaeus vannamei). Six diets were formulated: three diets without L. acidophilus containining 0 (control, ME0), 2.5 (ME2.5), and 5.0 g/kg of moringa (ME5.0) and the same three diets containing L. acidophilus at 1 × 10 7  CFU/g of diet (ME0+P, ME2.5 + P, and ME5.0 + P, respectively). Growth performance was measured after 60 days of the rearing period. On the final day, the shrimp were sampled to assess enzyme activity, intestinal and hepatopancreatic histology, and gut microbiota. Shrimp hemocytes were examined on Days 0, 1, 2, 4, 7, 14, 21, and 28 to measure the immune response in terms of the total hemocyte count, phenoloxidase activity, phagocytosis, and superoxide anion production. Furthermore, the shrimp were challenged with V. alginolyticus and V. parahaemolyticus. The results revealed that ME2.5 + P significantly increased (P < 0.05) final weight, weight gain, specific growth rate, enzyme activities, and villi height compared with ME2.5 and control. Wall thickness was increased in the shrimp fed diet supplemented with moringa and L. acidophilus compared with the control shrimp. Hepatopancreatic histology revealed that R cells were more abundant in the shrimp fed diet containing moringa and L. acidophilus compared with those fed diet containing moringa alone (P < 0.05) at the same concentration. High-throughput sequencing analysis indicated that the dietary supplementation with moringa and L. acidophilus affected the gut microbiota composition. All gene functions, members of KEGG level 2, related to metabolism were increased in diet supplemented with moringa with or without L. acidophilus compared with the control group. The immune assay revealed that the total hemocyte count, phenoloxidase activity, phagocytic rate, superoxide anion production, and immune-related gene expression (including those of prophenoloxidase II, alpha-2-macroglobulin, penaeidin2, antilipopolysaccharide factor, crustin, lysozyme, glutathione peroxidase, and superoxide dismutase) were higher in the experimental groups than in the control group on several observed days; however, the increases were observed more often in the ME2.5 + P group than in the other treatment groups. Furthermore, the ME2.5 + P group exhibited a significantly higher survival rate (P < 0.05) in the challenge test against V. alginolyticus and V. parahaemolyticus. In conclusion, supplementation with dietary moringa and L. acidophilus at ME2.5 + P improved growth performance, immune system, and resistance against Vibrio in the shrimp., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Trivalent arsenic (As (III)) contamination in the marine environment can produce adverse effects in crustaceans. The present study investigated the chronic toxicity of As (III) in white shrimp (Penaeus vannamei) by analyzing the tissue bioaccumulation and non-specific immune responses. Shrimps were exposed to 0 (control), 50, 500, and 2500 μg/L of As (III) for 21 days. The results showed that the hepatopancreas was the main tissue of arsenic accumulation in white shrimp. The cumulative concentration of total arsenic and inorganic arsenic but not arsenobetaine was positively correlated with the exposure concentration. In vitro As (III) treatment (0-2500 μg/L) with haemocytes isolated from healthy shrimp did not cause the cytotoxicity, but this arsenic treatments inhibited the phagocytic rate and O 2 - production. Moreover, the decrease of total haemocyte count and the inhibition of phagocytic rate, phagocytic index, O 2 - production and phenoloxidase activity were observed in white shrimp under the exposure of As (III) over a period of 21 days. This study revealed that chronic As (III) stress could disturb arsenic metabolism and immune responses in P. vannamei., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

This study investigated the effects of guava leaf extract (GLE) on immune responses, growth performance, and resistance to Vibrio parahaemolyticus in white shrimp (Penaeus vannamei). To examine the effect of GLE on the immune response of white shrimps, they were treated with various concentrations of GLE on hemocyte (in vitro) and were orally administered (in vivo) feed containing various concentrations of 0, 1, 5, and 10 g kg -1  GLE (control, GLE1, GLE5, and GLE10, respectively) for 28 days. Furthermore, their growth performance was evaluated for 56 days. In a separate experiment, the shrimps were challenged with V. parahaemolyticus injection after 7 days of culture. In vitro experiments indicated that GLE is nontoxic and can activate immune response. In vivo experiments revealed that the GLE5 led to the highest total hemocyte count, phenoloxidase activity, phagocytic activity, and superoxide anion production and the highest upregulation of lipopolysaccharide, β-1,3-glucan-binding protein, peroxinectin, lysozyme, crustin, penaeidin 2, penaeidin 3, clotting protein, superoxide dismutase, and glutathione peroxidase. Moreover, better growth performance was observed in the GLE groups, with GLE5 exhibiting the highest specific growth rate, weight gain, and feed conversion rate. In addition, GLE5 enhanced resistance to V. parahaemolyticus, with a survival rate of 72.27%. In conclusion, GLE was found to be effective in enhancing nonspecific immune response and growth performance and in reducing V. parahaemolyticus infection in white shrimp., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

This study investigates the effects of Phyllanthus amarus extract (PAE) on immune responses, growth, and resistance to Vibrio alginolyticus in white shrimp (Litopenaeus vannamei). In vitro PAE treatment did not alter the cell viability of haemocytes and significantly enhanced immune parameters such as phenoloxidase (PO) activity, phagocytic activity, and superoxide anion (O 2 - ) production. We conducted two feeding trials to examine the effects of PAE on the growth, disease resistance, and innate immune parameters of white shrimp. In the first in vivo trial, shrimps (4.01 ± 0.03 g) were fed a diet containing 0 g (control), 10 g (PAE10), 20 g (PAE20), or 40 g (PAE40) of PAE per kilogram of feed for 56 days. After the feeding period, the PAE20 group showed a significantly higher weight gain and specific growth rate than shrimp fed the control diet. Furthermore, after challenge with V. alginolyticus, shrimp fed a diet containing PAE showed significantly higher survival than those fed the control diet. The second in vivo trial (28 days) was performed to identify the mechanisms of enhanced immunity in PAE-fed shrimp. Shrimp fed the PAE20 diet generally had the highest total haemocyte count, PO activity, phagocytic activity, and O 2 - production, followed by the PAE40 and PAE10 groups. Thus, our results suggest that administration of 20 g of PAE per kilogram of feed can enhance immunity, growth, and resistance to V. alginolyticus in white shrimp., (Copyright © 2020. Published by Elsevier Ltd.)

This study investigates the effects of three medicinal herbal extracts, namely Bidens pilosa (BPE), Lonicera japonica (LJE), and Cyathula officinalis (COE), on nonspecific immune parameters of cobia (Rachycentron canadum) in vitro and in vivo. During in vitro tests, BPE treatment increased reactive oxygen species (ROS) production in a dose-dependent manner in primary head kidney leukocytes. Similarly, ROS production rates were enhanced by LJE (50 and 100 mg/ml) and COE (100 mg/ml). This suggests that these three herbal extracts possess immunostimulating properties. We then conducted two feeding trials to examine the effects of these three herbal extracts on growth and innate immune parameters of cobia, and sought an optimal dietary supplementation proportion required for activating the non-specific immune responses. In the first trial, we supplemented the diet with 1, 5, or 10% of the individual extracts. After a ten-week feeding trial, no negative impacts on weight gain, feed conversion rate, and survival rate were observed in fish offered experimental diets. Further, ROS production, phagocytic capacity of the head kidney leukocytes, and serum lysozyme activity were enhanced by differing degrees in fish fed the herbal extracts compared to fish in the control group. A similar albumin/globulin ratio was seen between each experimental group and the control group regardless of the type and dose of herbal extract used, indicating these medicinal herbal extracts are safe for cobia. We then performed a 30-day feeding trial with lower extract concentrations (1, 3, and 5% of the diet) to identify dose responses in cobia at various time points so that we could establish a cost-effective manner of administering the three extracts for cobia. All BPE fed fish had higher ROS production compared to the control group, while phagocytosis rate and index were simultaneously raised in only the BPE30 group (3% BPE). Immune parameters such as ROS production, phagocytic rate, and serum lysozyme activity were triggered when fish received 30 g LJE per kg of feed. However, ROS production only increased in the LJE10 group (1% LJE) on day 30 and was not enhanced in the LJE50 group (5% LJE). Additionally, although the phagocytic rate and phagocytic index were induced in the LJE50 group, serum lysozyme activity was not elevated in this group (LJE50) at any time point examined. ROS production was greatly improved in all COE fed groups, but only the COE30 group (3% COE) showed prolonged enhanced phagocytic rate over the 30-day feeding trial., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

The white shrimp Litopenaeus vannamei is one of the most commercially important aquatic species. However, intensive farming to meet economic demands has been linked to animal stress and subsequent disease outbreaks. In this study, we explore the immunomodulatory effects of Sargassum horneri hot-water extract (SHE) on the immune parameters of L. vannamei. Hemocytes incubated in vitro with 10 mg/ml of SHE showed the highest response in phenoloxidase (PO) activity and reactive oxygen species production. In the in vivo trials, shrimp were fed diets containing 0 (control), 2.5 (SHE 2.5), 5.0 g (SHE 5.0), and 10 g (SHE10.0) of lyophilized SHE per kg feed for four weeks, after which immune parameters were measured. Group SHE10.0 had the highest total hemocyte count, reactive oxygen species production, and phagocytic rate during the 4-week feeding period, followed by groups SHE5.0 and SHE2.5. However, group SHE5.0 showed a better growth performance among all examined groups after four weeks of rearing. Furthermore, gene expression analysis revealed that L. vannamei fed diets containing 0.5% SHE over 28 days showed significant modulation of 11 immune-related genes, including prophenoloxidase I, prophenoloxidase II, peroxinectin, α2macroglobulin, clotting protein, lysozyme, superoxide dismutase, glutathione peroxidase, penaiedin2-4, and crustin. Combined, these results show that SHE is a functional feed additive that can be applied orally to enhance innate immunity and growth performance of white shrimps., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study was conducted to examine the combinatory effects of β-glucan and oxytetracycline (OTC) on hybrid giant tiger groupers (Epinephelus fuscoguttatus × Epinephelus lanceolatus). In vitro tests, OTC significantly reduced superoxide anion production and phagocytic activity in primary head kidney leukocytes. However, this suppressive effect was alleviated by co-treatment with β-glucan. Subsequently, feeding trials were performed to investigate the potential immunomodulatory effects of dietary β-glucan alone or in combination with OTC on groupers. A total of 210 healthy groupers (368.00 ± 51.03 g) were divided into six groups. Group 1 was the control group, group 2 (BG) received 5 g β-glucan per kg feed weight, groups 3-5 received 5 g/kg β-glucan in combination with 10, 30, or 50 mg OTC/kg fish weight/day (groups M1, M2, and M3, respectively), and group 6 (O) received 50 mg OTC/kg fish weight/day. Fish were sampled to determine the innate immunity parameters and residual OTC levels in the muscle tissue during a 28-day feeding regimen. Residual OTC levels were considerably higher in groups M3 and O compared with the other groups, and peaked on day 14. This was followed by a slight decrease on day 28, despite a continuous supply of OTC. Notably, fish fed with OTC alone had significantly decreased phagocytic rates and superoxide anion production observed in head kidney leukocytes, as well as poorer protection against Vibrio alginolyticus infection. These immunosuppressive effects were not observed in the fish fed with β-glucan in combination with a lower dose of OTC (group M2). Thus, these data suggest that the combination of dietary β-glucan and OTC exerts synergistic immunostimulating effects that protect groupers from bacterial infection., Competing Interests: Declaration of competing interest The authors declare that they have no conflicts of interest., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

White spot syndrome virus (WSSV) is a large enveloped DNA virus, and it causes a serious disease that has led to severe mortalities of cultured shrimps in many countries. To determine the mechanism of virus entry into the cell and to establish an antiviral strategy, the cell receptor for virus entry and receptor binding protein should be identified. A shrimp cell surface protein, glucose transporter1 (Glut1), was found to interact with WSSV in previous study. In this study, this Glut1 was confirmed to have the ability of transporting glucose, and this gene can also be found in other shrimp species. The interaction between Glut1 and some other WSSV envelope proteins in the infectome structure was verified by far western blot and His pull down assay. In vitro and in vivo neutralization using recombinant partial Glut1 revealed that the large extracellular portion of Glut1 could delay WSSV infection. Also, shrimps which were knocked-down Glut1 gene by treated with dsRNA before WSSV challenge showed decreased mortality. These results indeed provide a direction to develop efficient antiviral strategies or therapeutic methods by using Glut1., (Copyright © 2015 Elsevier Ltd. All rights reserved.)