Effect of saponin immersion on enhancement of the immune response of white shrimp Litopenaeus vannamei and its resistance against Vibrio alginolyticus

Transcriptomics and gut microbiome analysis of the edible herb Bidens pilosa as a functional feed additive to promote growth and metabolism in tilapia (Oreochromis spp.)

To reduce the use of antibiotics and chemicals in aquaculture, an edible herb, Bidens pilosa, has been selected as a multifunctional feed additive. Although there has been considerable research into the effects of B. pilosa on poultry, the wider effects of B. pilosa, particularly on the growth and gut microbiota of fish, remain largely unexplored. We aimed to investigate the interactive effects between the host on growth and the gut microbiota using transcriptomics and the gut microbiota in B. pilosa-fed tilapia. In this study, we added 0.5% and 1% B. pilosa to the diet and observed that the growth performance of tilapia significantly increased over 8 weeks of feeding. Comparative transcriptome analysis was performed on RNA sequence profiles obtained from liver and muscle tissues. Functional enrichment analysis revealed that B. pilosa regulates several pathways and genes involved in amino acid metabolism, lipid metabolism, carbohydrate metabolism, endocrine system, signal transduction, and metabolism of other amino acids. The expression of the selected growth-associated genes was validated by qRT-PCR. The qRT-PCR results indicated that B. pilosa may enhance growth performance by activating the expression of the liver igf1 and muscle igf1rb genes and inhibiting the expression of the muscle negative regulator mstnb. Both the enhancement of liver endocrine IGF1/IGF1Rb signaling and the suppression of muscle autocrine/paracrine MSTN signaling induced the expression of myogenic regulatory factors (MRFs), myod1, myog and mrf4 in muscle to promote muscle growth in tilapia. The predicted function of the gut microbiota showed several significantly different pathways that overlapped with the KEGG enrichment results of differentially expressed genes in the liver transcriptomes. This finding suggested that the gut microbiota may influence liver metabolism through the gut-liver axis in B. pilosa-fed tilapia. In conclusion, dietary B. pilosa can regulate endocrine IGF1 signaling and autocrine/paracrine MSTN signaling to activate the expression of MRFs to promote muscle growth and alter the composition of gut bacteria, which can then affect liver amino acid metabolism, carbohydrate metabolism, endocrine system, lipid metabolism, metabolism of other amino acids, and signal transduction in the host, ultimately enhancing growth performance. Our results suggest that B. pilosa has the potential to be a functional additive that can be used as an alternative to reduce antibiotic use as a growth promoter in aquaculture.

Integrated Metabolome and Transcriptome Analyses Reveal the Efficacy of Steroidal Saponins for Glucose and Lipid Metabolism in Hybrid Grouper (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatu) Fed Higher-Lipid Diets

An analysis of the extent of the effect of steroidal saponin addition on glucose and lipid metabolism in hybrid grouper liver was performed at the transcriptomic and metabolomic levels. Feeds (52% crude protein, 14% crude lipid) were prepared containing 0% (S0), 0.1% (S0.1), and 0.2% (S0.2) steroidal saponins. After eight weeks of feeding trial, compared to the S0 group, the activities of serum albumin, alanine aminotransferase, and aspartate transaminase were significantly lower and the activities of lysozyme, acid phosphatase, and alkaline phosphatase were significantly higher in the S0.1 group (p < 0.05). The superoxide dismutase, catalase, and glutathione peroxidase activities in the livers of the S0.1 group were significantly higher than those of the S0 group, while the malondialdehyde content was significantly lower than that of the S0 group (p < 0.05). There were forty-two differentially expressed genes and thirty-two differential metabolites associated with glucose and lipid metabolism enriched using KEGG and GO. In the S0 group, the expression of prostaglandin-endoperoxide synthase 1, prostaglandin E synthase 1, and thromboxane-2 synthase mRNA was significantly higher than in the S0.1 group (p < 0.05). The expression levels of genes in the S0 group were significantly higher than those in the S0.1 group (p < 0.05), including for glycogen synthase kinase, glucose-6-phosphatase catalytic subunit 2, fructose-1,6-bisphosphatase, phosphoenolpyruvate carboxykinase, glucose transporter 4, and malate dehydrogenase. The expression of mRNA such as fatty acid synthase, acetyl-CoA carboxylase, and sterol regulatory element-binding protein 1 was significantly lower in the S0.1 group than in the S0 group, while the expression of carnitine acyltransferase 1, acyl-CoA synthetase, and acyl-CoA dehydrogenase genes was significantly higher in the S0 group (p < 0.05). In summary, glycogen synthesis, gluconeogenesis, and the arachidonic acid metabolism pathway were inhibited by 0.1% steroidal saponins, and glycogenolysis, glycolysis, the tricarboxylic acid cycle, and the fatty acid β-oxidation pathway were activated. This study aims to provide a reference for the formulation of grouper feeds with a higher crude-lipid level.

Effects of Dietary Steroid Saponins on Growth Performance, Serum and Liver Glucose, Lipid Metabolism and Immune Molecules of Hybrid Groupers (♀Epinephelus fuscoguttatus × ♂Epinephelus lanceolatu) Fed High-Lipid Diets

High-lipid diets are attributed to excessive lipid deposition and metabolic disturbances in fish. The aim of this experiment was to investigate the effects of steroidal saponins on growth performance, immune molecules and metabolism of glucose and lipids in hybrid groupers (initial weight 22.71 ± 0.12 g) fed high-lipid diets. steroidal saponins (0%, 0.1% and 0.2%) were added to the basal diet (crude lipid, 14%) to produce three experimental diets, designated S0, S0.1 and S0.2, respectively. After an 8-week feeding trial, no significant differences were found between the S0 and S0.1 groups in percent weight gain, specific growth rate, feed conversion ratio, protein efficiency ratio and protein deposition rate (p > 0.05). All those in the S0.2 group were significantly decreased (p < 0.05). Compared to the S0 group, fish in the S0.1 group had lower contents of serum triglyceride and low-density lipoprotein cholesterol and higher high-density lipoprotein cholesterol and glucose (p < 0.05). The activities of superoxide dismutase, catalase and glutathione peroxidase were significantly higher, and malondialdehyde contents were significantly lower in the S0.1 group than in the S0 group (p < 0.05). Hepatic triglyceride, total cholesterol and glycogen were significantly lower in the S0.1 group than in the S0 group (p < 0.05). Activities of lipoprotein lipase, total lipase, glucokinase and pyruvate kinase, and gene expression of lipoprotein lipase, triglyceride lipase and glucokinase, were significantly higher in the S0.1 group than in the S0 group. Interleukin-10 mRNA expression in the S0.1 group was significantly higher than that in the S0 group, while the expression of interleukin-6 and tumor necrosis factor-α genes were significantly lower than those in the S0 group. In summary, adding 0.1% steroidal saponins to a high-lipid diet not only promoted lipolysis in fish livers, but also activated glycolysis pathways, thus enhancing the utilization of the dietary energy of the groupers, as well as supporting the fish's nonspecial immune-defense mechanism.

Micro-Aid Liquid 10 Promotes Growth Performance and Health Status of White Shrimp, Litopenaeus vannamei

An experiment was conducted to evaluate the effects of the Micro-Aid Liquid 10 (MAL10) (DPI Global, Porterville, CA, USA), a product made from yucca extract, on growth performance, gut microbiota, and resistance of white shrimp, Litopenaeus vannamei against infectious disease caused by Vibrio alginolyticus. MAL10 was added to shrimp rearing water at different levels of 0 (control), 0.25 mL m3−1 (W0.25), 0.5 mL m3−1 (W0.5), 1 mL m3−1 (W1), and 5 mL m3−1 (W5), respectively, once per week for 70 days. Growth performances, including final body weight, specific growth rate, average daily growth and percentage of weight gain, were significantly improved by adding the MAL10 at levels up to 5 mL m3−1, which may be due to the proliferation of B cells in hepatopancreas of MAL10-treated shrimp. No significant differences in the total viable count and Vibrio-like count in the gut of shrimp were recorded by spread plate method. In the challenge test, shrimp reared in the water supplemented with MAL10 at levels of 1–5 mL m3−1 had significantly lower cumulative mortality after a challenge test with V. alginolyticus compared to shrimp reared in the control, W0.25 and W0.5 groups. Next-generation sequencing indicated that the relative distribution of phylum Proteobacteria in control (80.4%) was higher than the W (77.4%). The proportion of Vibrio was primarily dominant genera in the shrimp intestine and highest in the control group compared to the W group, followed by Spongiimonas, Motilimonas, Demequina, and Shewanella genera. Although there was no statistically significant difference, higher α-diversity indices were recorded in the W5-treated group than in the control group. Therefore, it is considered that MAL10 could be used as a natural alternative in shrimp aquaculture to reduce the risk of infectious disease caused by pathogenic Vibrio and improve the growth performance of white shrimp.

Anti-vibrio and immune-enhancing activity of medicinal plants in shrimp: A comprehensive review

Disease epidemics in shrimp aquaculture increase apace with the development of aquaculture systems throughout the world. The disease caused by Vibrio spp. (vibriosis) is considered the most devastating, which has made it the most feared bacterial disease in the shrimp sector. In aquaculture, several strategies have already been applied to control Vibrio strains, including chemicals, probiotics, antibiotics, natural products from plants, including plant oils; hence, there has been considerable attention for using plants in shrimp aquaculture to provide sustainable, eco-friendly and safe compounds, such as alkaloids, saponins, terpenoids and flavonoids for replacing chemical compounds and antibiotics in current aquaculture. Medicinal plants may also have immunostimulating activity, increase growth and resistance in shrimps. The present paper aims to review the inhibition of Vibrio spp. in shrimp by medicinal plants, using both in vitro or/and in vivo techniques. Several medicinal plants appear capable of inhibiting growth of Vibrio pathogens outside living shrimp or in the body of shrimp, through enhancing growth and immune capacity when shrimps are fed or injected with them. In the current review Gracilaria spp. (Gracilariaceae family) and Sargassum spp. (family Sargassaceae) have been used most for in vitro and in vivo experiments. Among the terrestrial plants, Eucalyptus camaldulensis, Psidium guajava, Rhodomyrtus tomentosa, and Syzygium cumini (Myrtaceae family) had significant activity against Vibrio.

Sargassum wightii-synthesized ZnO nanoparticles - from antibacterial and insecticidal activity to immunostimulatory effects on the green tiger shrimp Penaeus semisulcatus

The green synthesis of metal nanoparticles using phytochemical from marine seaweeds is a fast-growing research field in nanotechnology. Here, the biosynthesis of zinc oxide nanoparticles was achieved using the hot water extract of Sargassum wightii. The hot water extract prepared from S. wightii (H Sw) and ZnO NPs were studied by UV-visible and FTIR spectroscopy, SEM and XRD. Then, both products were evaluated for antibiofilm activity towards aquatic pathogens. The nanoparticles' immunostimulating potential on green tiger prawns, Penaeus semisulcatus was studied through immersion and dietary administration. Shrimp immune parameters (i.e., total hemocytes count (THC), respiratory bursts (RBs), phenoloxidase (PO) and superoxide dismutase (SOD) activity) were significantly affected by exposure or ingestion of ZnO nanoparticles. In addition, the hot water extract and ZnO nanoparticles had high antibiofilm activity against Gram-positive (B. subtilis, S. aureus) and Gram-negative (S. sonnei, P. aeruginosa) microbial pathogens. It was accomplished that the ZnO nanoparticles can be used as the bacteriostatic and immunostimulant agents through immersion and dietary administration enhancing immunity of green tiger shrimp. Furthermore, the toxicity effects of ZnO nanoparticles were 100% at 24 h on Aedes aegypti 3 rd instar larvae at the concentration of 100 μg/mL and the greatest efficacy was accomplished by H Sw ZnO NPs against the Ae. aegypti after 24 h (LC50 49.22; LC90 86.96 mg/mL), if compared to the seaweed extract alone. Morphological and histological damages triggered by nanoexposure were investigated.

Immune defense of emodin enriched diet in Clarias batrachus against Aeromonas hydrophila

This study investigates the effect of emodin enriched diet on growth, hematology, and immune response in walking catfish, Clarias batrachus against Aeromonas hydrophila. The basal (control) diet supplemented with emodin at 0.0, 0.1, 0.2, or 0.4 g kg^-1 was fed to the experimental groups for a period of four weeks. Feeding infected fish with 0.2 g kg^-1 and 0.4 g kg^-1 emodin enriched diets resulted in an overall weight gain, enhanced PER and FCR when compared to other diets. The survival rates were 98.3% and 96.7% in 0.1 g kg^-1 and 0.4 g kg^-1 emodin diet fed groups. Feeding with 0.2 g kg^-1 diet the RBC level significantly elevated on week 1 and with 0.4 g kg^-1 diet on weeks 2 and 4. The WBC, the percentage of globulin and neutrophils increased significantly with 0.2 g kg^-1 diet only on week 4; however with 0.4 g kg^-1 diet the increase was observed from week 1-4. The phagocytic activity increased significantly on being fed with 0.4 g kg^-1 diet on week 2 while with 0.2 g kg^-1 and 0.4 g kg^-1 diets the increase manifested only on week 4; the respiratory burst activity also significantly increased on week 4 whereas increased the complement activity on weeks 2 and 4. The superoxide dismutase (SOD) activity was high on being fed with 0.4 g kg^-1 diet on week 1; with 0.2 g kg^-1 or 0.4 g kg^-1 diets the increase was observed on weeks 2 and 4. The serum IgM level significantly increased when fed with 0.4 g kg^-1 diet whereas the lysozyme activity was enhanced with 0.2 g kg^-1 and 0.4 g kg^-1 emodin diets on weeks 2 and 4. The percentage cumulative mortality was 10% with 0.1 g kg^-1 or 0.2 g kg^-1 diets while with 0.2 g kg^-1 diet it was 15%. The results demonstrate that as a feed additive emodin acts as an immunostimulant enhancing the specific and nonspecific immune defense affording increased disease protection, enhances better growth and boosts hematology parameters in C. batrachus against A. hydrophila infection.

Role of medicinal plants on growth performance and immune status in fish

Disease outbreaks increase proportionally with increases in intensive aquaculture. Natural products including medicinal plants have been known from thousands of years for treating some human diseases. It is well known that many active compounds are responsible for potential bio-activities. For that reason, there has been considerable interest in the use of medicinal plants in aquaculture with a view to providing safe and eco-friendly compounds for replacing antibiotics and chemical compounds as well as to enhance immune status and control fish diseases. This article describes a wide range of medicinal plants such as herbs, seeds, and spices with different forms such as crude, extracts, mixed and active compounds, used as immunostimulants and resulting in a marked enhancement in the immune system of fish to prevent and control microbial diseases. Moreover, different activity was recorded from plant parts like seeds, roots, flowers and leaves. The mode of action of medicinal plants was stimulation of the cellular and humoral immune response which was monitored through elevation in immune parameters. Various levels of immune stimulation have been shown by medicinal plants at different concentrations through injection or immersion or oral administration. However, it is critically important to determine the optimal dose to enhance the immune system of fish and avoid the risk of immunosuppression. Some medicinal plants have been used to replace the protein in fishmeal as a cheap source of protein and proved to be efficient in this respect. Medicinal plants can act as a growth promoter and immunomodulator at the same time. Further investigations should be carried out to examine the influence of those plants on fish health (including physiological and histological parameters) as a preliminary step for use in large scale in aquaculture. The current review describes the role of medicinal plants and their derivatives on innate and adaptive immune status as well as growth performance in fish.

Molecular characterization and function of the Prohibitin2 gene in Litopenaeus vannamei responses to Vibrio alginolyticus

Prohibitin2 (PHB2), a potential tumor suppressor protein, plays important roles in inhibition of cell cycle progression, transcriptional regulation, apoptosis and the mitochondrial respiratory chain. To explore its potential roles in crustaceans' immune responses we have identified and characterized LvPHB2, a 891 bp gene encoding a 297 amino acids protein in the shrimp Litopenaeus vannamei. Expression analyses showed that LvPHB2 is expressed in all examined tissues, and largely present in cytoplasm, correlating with its known anti-oxidation function in mitochondria. Luciferase reporter assays showed that over-expression of LvPHB2 could activate the p53 pathway, indicating that it might participate in apoptosis regulation. Quantitative real-time PCR revealed that infection with Vibrio alginolyticus induces its up-regulation in hepatopancreas. Moreover, RNAi knock-down of LvPHB2 in vivo raises mortality rates of L. vannamei infected by V. alginolyticus, and affects expression of STAT3, Caspase3 and p53 genes. We found significantly higher reactive oxygen species production, DNA damage and apoptosis rates in LvPHB2-silenced shrimp challenged with V. alginolyticus than in controls injected with a Green Fluorescent Protein-silencing construct. Our results suggest that LvPHB2 plays a vital role in shrimp responses to V. alginolyticus infection through its participation in regulation of oxidants and apoptosis.

Dietary administration of saponin stimulates growth of the swimming crab Portunus trituberculatus and enhances its resistance against Vibrio alginolyticus infection

The immunostimulatory role of dietary saponins on swimming crabs was investigated under field conditions. Portunus trituberculatus were fed diets enriched with Quillaja saponin (QS) at 150, 300 and 450 mg kg^-1. They had an enhanced growth rate and increased resistance against Vibrio alginolyticus compared to crabs not fed with QS. Significant effects were observed on the average body weight, percentage weight gain and specific growth rate (p < 0.05). Total hemocyte and hyaline cell counts of P. trituberculatus fed with 300 and 450 mg kg^-1 saponin in their diets significantly increased (p < 0.05) compared to the control. Phenoloxidase, superoxide dismutase, catalase and glutathione peroxidase activities significantly increased in response to the incorporation of QS in the diet. However, the respiratory burst activity did not increase significantly. The phagocytic activity was significantly enhanced at 300 and 450 mg kg^-1 of saponin. QS diets can enhance growth of P. trituberculatus and its immune resistance against V. alginolyticus. Dietary administration of saponin may help to control diseases and improve production in the crab aquaculture industry.

Adjuvant Effect of Quillaja saponaria Saponin (QSS) on Protective Efficacy and IgM Generation in Turbot (Scophthalmus maximus) upon Immersion Vaccination

The adjuvant effect of Quillaja saponaria saponin (QSS) on protection of turbot fry was investigated with immersion vaccination of formalin-killed Vibrio anguillarum O1 and various concentrations of QSS (5, 25, 45 and 65 mg/L). Fish were challenged at days 7, 14 and 28 post-vaccination. Significantly high relative percent of survival (RPS) ((59.1 ± 13.6)%, (81.7 ± 8.2)%, (77.8 ± 9.6)%) were recorded in the fish that received bacterins immersion with QSS at 45 mg/L, which is comparable to the positive control group vaccinated by intraperitoneal injection (IP). Moreover, a remarkably higher serum antibody titer was also demonstrated after 28 days in the vaccinated fish with QSS (45 mg/L) than those vaccinated fish without QSS (p < 0.05), but lower than the IP immunized fish (p < 0.05). Significant upregulation of IgM gene expression has also been identified in the tissues of skin, gill, spleen and kidney from the immunized fish in comparison to the control fish. Taken together, the present study indicated that QSS was able to dramatically evoke systemic and mucosal immune responses in immunized fish. Therefore, QSS might be a promising adjuvant candidate for fish vaccination via an immersion administering route.

Dietary effect of Sargassum wightii fucoidan to enhance growth, prophenoloxidase gene expression of Penaeus monodon and immune resistance to Vibrio parahaemolyticus

The polysaccharide fucoidan from brown seaweed Sargassum wightii was extracted and it was incorporated with pellet diets at three concentrations (0.1, 0.2 & 0.3%). The fucoidan incorporated diets were fed to shrimp Penaeus monodon for 60 days and the growth performance was assessed. The weight gain and SGR of control group was 6.83 g and 9.72%, respectively, but the weight gain and SGR of various concentrations (0.1-0.3%) of fucoidan incorporated diets fed groups of shrimp was increased from 7.30 to 8.20 g and 9.83 to 10.03%, respectively. After 60 days of feeding experiment, the relative quantification of prophenoloxidase gene of experimental groups over control group was analysed by RT-PCR and it was ranged between 2.13 and 7.95 fold increase within 33.52-34.61 threshold cycles, respectively at 0.1-0.3% concentrations of fucoidan. After 60 days of feeding experiment, the P. monodon were challenged with shrimp pathogen Vibrio parahaemolyticus and the mortality percentage was recorded daily up to 21 days. The reduction in mortality percentage of experimental groups over control group was recorded from 44.56 to 72.79%, respectively in 0.1-0.3% of fucoidan incorporated diets fed groups. During challenge experiment, all the immunological parameters such as THC, prophenoloxidase activity, respiratory burst activity, superoxide dismutase activity, phagocytic activity, bactericidal activity and bacterial clearance ability of experimental groups were significantly (P < 0.05) increased than control group. The V. parahaemolyticus load was enumerated from the infected shrimp at every 10 days intervals during challenge experiment. In control group, the Vibrio load was increased in hepatopancreas and muscle tissues from 10th to 21st days of challenge test. But in the experimental groups, the Vibrio load in both the tissues decreased positively from 10th to 21st days of challenge duration. It is concluded that the S. wightii fucoidan had enhanced the innate immunity and increased resistance to V. parahaemolyticus infection in P. monodon.

Dietary effect of Rubus coreanus ethanolic extract on immune gene expression in white leg shrimp, Penaeus vannamei

The objective of this study was to evaluate the effect of dietary supplementation of a Rubus coreanus ethanolic extract on immunostimulatory response in white leg shrimp Penaeus vannamei. Shrimps with an average initial weight of 0.5 ± 0.04 g were collected and acclimatized for 10 days. Four experimental diets including a control diet, a probiotic diet and 0.25 and 0.5% of R. coreanus ethanolic extract (RcEE) diets were used to feed the shrimps. After 8 weeks of culture, shrimp fed with probiotic and 0.25% RcEE diet had showed significant enhancement in the growth while shrimp fed with 0.5% RcEE diet showed significantly increased expression of immune genes and antioxidant enzymes activities. One week of challenge experiments for all the four diets fed shrimps showed decreased cumulative mortality in the 0.5% RcEE diets fed shrimps, when compared with the probiotic and 0.25% RcEE diet fed shrimp groups. The results indicates that R. coreanus ethanolic extract could be used as a herbal immunostimulant for shrimps to increase its immunity and disease resistance against the bacterial pathogen, Vibrio alginolyticus.

Effects of different dietary lipid level on the growth, survival and immune-relating genes expression in Pacific white shrimp, Litopenaeus vannamei

Five feeding trials based on the isonitrogenous and isoenergetic experimental diets containing 34% protein, 6%, 8%, 10%, 12% or 14% lipid respectively in the circulating water culture system for both 30 and 60 days were conducted to investigate the effect of the dietary lipid level on the growth and immunity in white shirmp, Litopenaeus vannamei adults. The body weight and specific growth rate of white shrimp in different treatments indicated that shrimps fed the diet of 12% lipid level for 30d and 10% lipid level for 60d had the best developmental status. The ability of respiratory burst in hemocytes was improved as the increase of dietary lipid level. The transcripts of LGBP and pPO were sensitive to the dietary lipid in hemocyte and hepatopancreas respectively. The activities of CAT, GPx and AKP were increased to a certain extend according to dietary lipid level. Qualification of MDA showed the lowest level in the sample subjected to 12% lipid level diet, indicating an optimal utilization of the dietary lipid and an efficient clearance of MDA in vivo. These results suggested that dietary lipid level of 10-12% significantly tunes the growth and enhance the immune abilities mainly via ROS pathway of L. vannamei.

WITHDRAWN: Effects of saponin supplementation diet on hematological, biochemical, and immunological responses in Epinephelus bruneus against Vibrio alginolyticus

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Dietary administration of a Gracilaria tenuistipitata extract enhances the immune response and resistance against Vibrio alginolyticus and white spot syndrome virus in the white shrimp Litopenaeus vannamei

The haemogram, phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, glutathione peroxidase (GPx) activity, lysozyme activity, and the mitotic index of haematopoietic tissue (HPT) were examined after the white shrimp Litopenaeus vannamei had been fed diets containing the hot-water extract of Gracilaria tenuistipitata at 0 (control), 0.5, 1.0, and 2.0 g kg(-1) for 7-35 days. Results indicated that these parameters directly increased with the amount of extract and time, but slightly decreased after 35 days. RBs, SOD activity, and GPx activity reached the highest levels after 14 days, whereas PO and lysozyme activities reached the highest levels after 28 days. In a separate experiment, white shrimp L. vannamei, which had been fed diets containing the extract for 14 days, were challenged with Vibrio alginolyticus at 2 × 10(6) cfu shrimp(-1) and white spot syndrome virus (WSSV) at 1 × 10(3) copies shrimp(-1), and then placed in seawater. The survival rate of shrimp fed the extract-containing diets was significantly higher than that of shrimp fed the control diet at 72-144 h post-challenge. We concluded that dietary administration of the G. tenuistipitata extract at ≤1.0 g kg(-1) could enhance the innate immunity within 14 days as evidenced by the increases in immune parameters and mitotic index of HPT in shrimp and their enhanced resistance against V. alginolyticus and WSSV infections. Shrimp fed the extract-containing diets showed a higher and continuous increase in the humoral response indicating its persistent role in innate immunity.

The effect of dietary Panax ginseng polysaccharide extract on the immune responses in white shrimp, Litopenaeus vannamei

The immunostimulatory effects of orally administered Panax ginseng root or its polysaccharides (GSP) in white shrimp, Litopenaeus vannamei, were investigated in this study. Shrimp were fed a diet containing 0.4 g kg⁻¹ GSP over a period of 84 days, during which the activities of total superoxide dismutase (T-SOD), catalase (CAT), glutathione peroxidase (GSH-Px), acid phosphatase (ACP), and alkaline phosphatase (AKP), as well as malondialdehyde (MDA) content, and expressions of cytosolic superoxide dismutase (cyt-SOD), CAT, GSH-Px, and peroxiredoxin (Prx) genes were determined in various tissues of the shrimp. Results showed that the shrimp fed the GSP diet had significantly increased ACP and AKP activities in the gills. The GSP-fed shrimp also displayed significantly increased T-SOD and GSH-Px activities in the gills and hepatopancreas of the shrimp; meanwhile there was enhanced CAT activity in the gills, but decreased MDA content in the gills, hepatopancreas and muscle. The mRNA expressions of cyt-SOD, CAT, GSH-Px and Prx were significantly elevated in the gills and hepatopancreas of the shrimp fed the GSP diet for 84 days, compared with that of the control. Therefore, GSP can be used as an immunostimulant for shrimp through dietary administration to increase immune enzyme activity and modify expression of immune genes in shrimp.