Effects of the water extract of Gynura bicolor (Roxb. & Willd.) DC on physiological and immune responses to Vibrio alginolyticus infection in white shrimp (Litopenaeus vannamei)

An Overview of the Biological Functions and Mechanisms of Action of Medicinal Plants and Seaweeds in the Shrimp Culture

Diseases are major constraints to developing large-scale aquaculture practices in many countries. For decades, synthetic chemotherapeutic agents have been widely applied both as prophylactics and therapeutics to inhibit and control aquatic disease outbreaks. However, their use has become more restricted due to the negative impacts they have on the environment, the host and humans, as well as their limitations in preventing the emergence of antimicrobial-resistant bacteria. Therefore, there is a growing interest in the use of medicinal plants and seaweeds as potential alternatives to antibiotics and other synthetic chemotherapeutics. Medicinal plants and seaweeds can enhance the immune systems of animals, thereby providing protection against numerous diseases while minimizing the adverse effects associated with synthetic chemotherapeutics. Furthermore, the advantages of medicinal plants and seaweeds, such as their effectiveness, easy availability and ability to be applied on a large scale, make them appealing for use in the aquaculture industry. The main goal of this study was to review the existing knowledge of the effects of medicinal plants and seaweeds, as well as their extracts, on shrimp growth, immune response and disease resistance against bacterial and viral agents. Moreover, this paper discusses the application of seaweeds in shrimp culture. We also conducted a literature review to identify gaps in the research and provide recommendations for further advancement in this field of study. Further studies should focus on evaluating other physiological aspects, such as feed and mineral utilization, enzyme activities and histological examination.

Survival, immune response and growth of Penaeid shrimp as affected by immunostimulants: A meta-analysis

Immunostimulants represent the most innovative approach for combating shrimp diseases. They are molecules that effectively enhance the host's nonspecific defenses against invading microorganisms. However, methodological differences exist among immunostimulants based on the same source. Therefore, conducting a meta-analysis is essential to derive valid conclusions. The effect size value utilized in this study was Hedges' d. Heterogeneity among studies was assessed using the DerSimonian and Laird tests (Q-statistic). Meta-regression analysis was conducted to explore the sources of heterogeneity in treatment effects. In this study, dose served as a covariate because it was the only continuous variable that significantly contributed to the observed heterogeneity. Funnel plots and the fail-safe number were employed to assess publication bias within the datasets. The article collection process followed the PRISMA methodology. Based on the results of the meta-analysis and meta-regression conducted with 83 articles, it can be concluded that immunostimulants have a significant effect, characterized by high category standard mean difference (SMD) values, on the survival, growth, and immune response of Penaeid family shrimp. Among potential immunostimulants options, algae ingredients exhibited the most favorable effects on the survival, growth, and immune response of Penaeid family shrimp. Subgroup analysis outcomes revealed that various extraction methods significantly impacted the efficacy of immunostimulants, with the ethanol solvent method proving to be the most effective. Among different administration methods, no significant effect was observed on immunostimulant efficacy across all parameters, with positive SMD values for all administration methods. Regarding challenged test pathogens, immunostimulants were observed to enhance immune response, survival, and weight gain against various pathogens. Meta-regression results indicated that algal treatments had a lower optimal dose point, leading to decreased efficacy as the dose increased. In contrast, fungi exhibited a higher optimum dose point, resulting in increased efficacy at higher doses.

Research progress of anthocyanin prebiotic activity: A review

BACKGROUND

Anthocyanins are a kind of flavonoids and natural water-soluble pigments, which endow fruits, vegetables, and plants with multiple colors. They are important source of new products with prebiotic activity. However, there is no systematic review documenting prebiotic activity of anthocyanins and their structural analogues. This study aims to fill this gap in literature.

PURPOSE

The objective of this review is to summarize and evaluate the prebiotic activity of anthocyanin's, and discuss the physical and molecular modification methods to improve their biological activities.

STUDY DESIGN AND METHODS

In this review, the databases (PubMed, Google Scholar, Web of Science, Researchgate and Elsevier) were searched profoundly with keywords (anthocyanin's, prebiotics, probiotics, physical embedding and molecular modification).

RESULTS

A total of 34 articles were considered for reviewing. These studies approved that anthocyanins play an important role in promoting the proliferation of probiotics, inhibiting the growth of harmful bacteria and improving the intestinal environment. In addition, physical embedding and molecular modification have also been proved to be effective methods to improve the prebiotic activity of anthocyanins. Anthocyanins could promote the production of short chain fatty acids, accelerate self degradation and improve microbial related enzyme activities to promote the proliferation of probiotics. They inhibited the growth of harmful bacteria by inhibiting the expression of harmful bacteria genes, interfering with the role of metabolism related enzymes and affecting respiratory metabolism. They promoted the formation of a complete intestinal barrier and regulated the intestinal environment to keep the body healthy. Physical embedding, including microencapsulation and colloidal embedding, greatly improved the stability of anthocyanins. On the other hand, molecular modification, especially enzymatic modification, significantly improved the biological activities (antioxidant, prebiotic activity and so on) of anthocyanins.

CONCLUSION

All these research results displayed by this review indicate that anthocyanins are a useful tool for developing prebiotic products. The better activities of the new anthocyanins formed by embedding and modification may make them become more effective raw materials. Our review provides a scientific basis for the future research and application of anthocyanins.

Ethanol extract of Gynura bicolour reduces atherosclerosis risk by enhancing antioxidant capacity and reducing adhesion molecule levels

CONTEXT

Gynura bicolour (Roxb. and Willd.) DC (Asteraceae) leaf is a common vegetable. Ethanol extracts of fresh G. bicolour leaves (GBEE) have several physiological effects, but studies on atherosclerosis are limited.

OBJECTIVE

We investigated the oxidant scavenging ability and vascular adhesion molecule expression of these extracts.

MATERIALS AND METHODS

The antioxidant effects of 0.05-0.4 mg/mL GBEE were analyzed in vitro. Intracellular antioxidant capacity and adhesion molecule levels were detected in EA.hy926 cells pre-treated with 10-100 μg/mL GBEE for 8 h, then TNF-α for 3 h. The antioxidant capacity of red blood cells and the adhesion molecule levels in the thoracic aorta were detected in high-fat diet (HFD)-fed Sprague-Dawley rats treated with GBEE for 12 weeks.

RESULTS

The in vitro EC₅₀ values of GBEE based on its DPPH radical-scavenging ability, reducing power, and ferrous ion-chelating ability were 0.20, 3.21 and 0.49 mg/mL, respectively. In TNF-α-treated EA.hy926 cells, the thiobarbituric acid-reactive substance levels were decreased after 10, 50, or 100 μg/mL GBEE treatments (IC₅₀: 19.1 mg/mL). When HFD-fed rats were co-treated with GBEE, the GBEE-H group exhibited 25% higher glutathione levels than the HFD group (p < 0.05). E-selectin, intercellular adhesion molecule-1, and vascular cell adhesion protein-1 levels were decreased in TNF-α-treated EA.hy926 cells after GBEE treatment (by approximately 11-73%; p < 0.05), and the above three adhesion molecules levels were decreased in HFD-fed rats with combined GBEE treatment (by approximately 30-77%; p < 0.05).

CONCLUSIONS

GBEE can protect the vascular endothelium by reducing adhesion molecule expression and regulating antioxidants. It may have the potential to prevent atherosclerosis.

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.

Effect in white shrimp Litopenaeus vannamei of Eleutherine bulbosa (Mill.) Urb. Powder on immune genes expression and resistance against Vibrio parahaemolyticus infection

This study investigated the influence of Eleutherine bulbosa (Mill.) Urb. on the immune responses, bacterial population in the intestines, and resistance of white shrimp, Litopenaeus vannamei, against infection with Vibrio parahaemolyticus. Shrimp were fed with three dosages of powder, at 6.25 g kg-1 (P6.25), 12.5 g kg-1 (P12.5), and 25 g kg-1 (P25). One dosage of the crude extract was provided, 1.25 g kg-1 (E1.25), and the controls without administration of E. bulbosa consisted of a positive control (PC) and a negative control (NC). Feed supplementation was carried out for 30 days; then shrimp from all treatments were challenged by intramuscular injection with V. parahaemolyticus (10⁶ cfu/mL), except for the NC. The results showed that supplementation with the powder and extract of E. bulbosa for 30 days resulted in significantly higher (P < 0.05) immune responses (total hemocyte count (THC), phenoloxidase activity (PO), respiratory bursts (RBs)), gene expression (prophenoloxidase (proPO), lipopolysaccharide- and β-1,3-glucan-binding protein (LGBP)), and total bacterial count (TBC) compared to PC/NC. In post challenge testing, there were significantly higher levels for THC, PO, RBs, proPO, LGBP, and PE (peroxinetin), and the treatments were able to suppress V. parahaemolyticus in the intestines, hepatopancreas, and muscles and to reduce damage to the muscles and hepatopancreas. The survival rate with P12.5 was significantly higher compared to the other treatments. It was concluded that the shrimp receiving supplementation with the powder and extract of E. bulbosa had increased immunity and resistance against V. parahaemolyticus infection, with the best dosage being the P12.5 treatment.

Effects of dietary anthocyanin on innate immune parameters, gene expression responses, and ammonia resistance of Nile tilapia (Oreochromis niloticus)

The present study investigated the effects of dietary anthocyanin on the growth performance, haematological, non-specific immune, and spleen gene expression responses of Nile tilapia, Oreochromis niloticus. Five experimental groups of fish with mean weights of 8.24 ± 0.64 g were used in the study; four of these were fed with diets incorporating anthocyanin (20 mg kg -¹, 40 mg kg^-1, 80 mg kg^-1 and 160 mg kg^-1), while the fifth was a control group without dietary anthocyanin. Growth performance and haematological parameters of tilapia were not affected by anthocyanin-supplemented diets (p > 0.05). Dietary anthocyanin significantly increased respiratory burst activity, phagocytic activity, phagocytic index, lysozyme activity, myeloperoxidase activity, serum total superoxide dismutase (T.SOD) activity, and serum catalase (CAT) activity (p < 0.05). The total immunoglobulin level was highest in the 80 mg kg^-1 group compared with the other groups (p < 0.05). In addition, with the anthocyanin-containing diets, the gene levels of interleukin 1, beta (IL-1β), interleukin 8 (IL-8), tumor necrosis factor (TNF-α), heat shock protein 70 (HSP70), and interferon gamma (IFN-γ) were increased in the fish spleen, and the gene levels of CAT, GPx, and SOD were also increased in fish liver (p < 0.05). At the end of the experiment, the fish were subjected to ammonia stress. The groups fed with 20 and 40 mg kg^-1 anthocyanin exhibited higher survival rates than the other groups. In summary, feeding Nile tilapia with anthocyanin-containing diets caused increases in the innate immune parameters, gene expression responses, and the survival rate of the fish subjected to ammonia stress.

α-Phellandrene enhances the immune response and resistance against Vibrio alginolyticus in white shrimp (Litopenaeus vannamei)

Innate immunity and resistance against Vibrio alginolyticus in white shrimp, Litopenaeus vannamei, that received α-phellandrene were examined. The results indicated that the percent survival of shrimp receiving 4, 8, and 12 μg g^-1 α-phellandrene was significantly higher than that of control shrimp after 72 h (p < 0.05). In a separate experiment, the phenoloxidase (PO), respiratory bursts, superoxide dismutase (SOD), and phagocytic and lysozyme activity of L. vannamei receiving 8 and 12 μg g^-1 α-phellandrene were significantly higher than those of the other groups upon challenge with V. alginolyticus at 24-60, 36-60, 12-60, 12-72 and 48-72 h, respectively. However, no significant differences in the total haemocyte counts (THC) of L. vannamei receiving any dose of α-phellandrene and of control shrimp were observed at 12-72 h. The expression (mRNA transcripts) of the immune genes prophenoloxidase (proPO), LPS- and β-1,3-glucan-binding protein (LGBP) and peroxinectin (PE) of shrimp receiving α-phellandrene at 8 and 12 μg g^-1 significantly increased after challenge with V. alginolyticus for 72 h (p < 0.05). We conclude that the immune ability and resistance against V. alginolyticus infection increased in L. vannamei receiving >4 μg g^-1 α-phellandrene. These results indicated that α-phellandrene plays an important role in the innate immunity of white shrimp.

A synbiotic improves the immunity of white shrimp, Litopenaeus vannamei: Metabolomic analysis reveal compelling evidence

In this study, we examined the synergistic effects of a diet-administered synbiotic comprising galactooligosaccharide (GOS) and the probiotic Lactobacillus plantarum 7-40 on immune responses, immune-related gene expressions, and disease resistance to Vibrio alginolyticus in white shrimp Litopenaeus vannamei. To unravel the regulatory role of the synbiotic in activating the immune system of shrimp, ¹H nuclear magnetic resonance (NMR)-based metabolomic analysis were used to investigate hepatopancreas metabolites, then significantly altered metabolites were confirmed in both the hepatopancreas and plasma by reverse-phase high-performance liquid chromatography (RP-HPLC) and spectrophotometric analysis. Shrimp were fed four experimental diets for 60 days, including a basal diet with no GOS or probiotic (control), 0.4% GOS (PRE), probiotic (PRO), and 0.4% GOS in combination with the probiotic (SYN). Results showed that the SYN diet significantly increased survival of L. vannamei 24 h after a V. alginolyticus injection. Immune parameters such as phenoloxidase activity, respiratory bursts, phagocytic activity and gene expressions, including prophenoloxidase I, serine proteinase, and peroxinectin, of shrimp fed the SYN diet significantly increased, compared to the other treatments and control. In addition, results from the ¹H NMR analysis revealed that 22 hepatopancreas metabolites were matched and identified between the SYN and control groups, among which three metabolites, i.e., inosine monophosphate (IMP), valine, and betaine, significantly increased in the SYN group. Confirmation using RP-HPLC and spectrophotometric methods showed that IMP presented high amounts in the hepatopancreas, but not in the plasma of shrimp; in contrast, valine and betaine metabolites were in high concentrations in both the hepatopancreas and plasma. Our results suggested that GOS and the probiotic had a synergistic effect on enhancing immunity and disease resistance of L. vannamei against V. alginolyticus infection through inducing syntheses of a nucleotide (IMP), a branched amino acid (valine), and a methyl group donor (betaine) in the hepatopancreas, which were then released into the plasma and directly taken up by hemocytes, resulting in a triggering of melanization and phagocytosis processes in cells.

Effects of dietary hawthorn extract on growth performance, immune responses, growth- and immune-related genes expression of juvenile golden pompano (Trachinotus ovatus) and its susceptibility to Vibrio harveyi infection

The present study was conducted to investigate the effects of dietary hawthorn extract (HTE) supplementation on growth performance, immune responses, hepatic antioxidant abilities, growth- and immune-related and heat shock protein genes expression and resistance to the pathogen Vibrio harveyi in Trachinotus ovatus. A basal diet supplemented with HTE at 0 (Diet 1), 0.50 (Diet 2), 1.00 (Diet 3), 2.00 (Diet 4), 4.00 (Diet 5) and 10.00 (Diet 6) g kg^-1 were fed to golden pompano for 8 weeks. The highest final body weight, weight gain rate, specific growth rate, feed efficiency ratio and protein efficiency rate were observed in fish fed Diet 2 (P < 0.05). Dietary HTE significantly increased plasma complement 3, complement 4 and immunoglobulin M content (P < 0.05). Hepatic antioxidant enzymes (SOD, T-AOC, CAT, GPx, GR) significantly increased (P < 0.05), whereas MDA content decreased first and then increased in fish fed HTE supplement. After challenge with Vibrio harveyi, significant higher post-challenge survival was observed in fish fed Diet 2 and Diet 3 than the control group (P < 0.05). Transcription levels of growth-related genes (IGF-I and IGF-II) were significantly up-regulated in fish fed HTE supplement (P < 0.05), whereas HSP70 and HSP90 mRNA levels were significantly down-regulated (P < 0.05). With respect to immune-related genes, such as tumour necrosis factor-alpha (TNF-α), interleukin-8 (IL-8) and inhibitor protein κBα (IκB-α), upregulation was observed in the liver of fish fed with the diet supplemented with HTE. In contrast, the expression of antioxidant enzyme genes (CAT, GPx, MnSOD and Keap1) and cytokines (IL-10, TGF-β1 and TOR) was downregulated. These results indicated that golden pompano fed a diet supplemented with 0.50 g kg^-1 HTE could significantly promote growth performance and growth-related genes expression, strengthen immunity, and improve hepatic antioxidative abilities and resistance to Vibrio harveyi infection.

Effects of dietary dandelion extracts on growth performance, body composition, plasma biochemical parameters, immune responses and disease resistance of juvenile golden pompano Trachinotus ovatus

The present study was conducted to investigate the effects of dietary dandelion extracts (DE) supplementation on growth performance, feed utilization, body composition, plasma biochemical indices, immune responses, hepatic antioxidant abilities, and resistance to the pathogen Vibrio harveyi in Trachinotus ovatus. A basal diet supplemented with DE at 0, 0.50, 1.00, 2.00, 4.00 and 10.00 g kg^-1 were fed to golden pompano for 8 weeks. The study indicated that dietary supplementation with DE could significantly improve final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed efficiency ratio (FER), feed intake (FI), protein efficiency ratio (PER) and protein deposit rate (PDR) (P < 0.05). The highest FBW, WGR, SGR, FI and PDR were observed in fish fed 1.00 g kg^-1 dietary DE (P < 0.05). The highest FER and PER were recorded at 0.50 g kg^-1 dietary DE (P < 0.05). Condition factor, viscerosomatic index, hepatosomatic index and survival were not significantly different among all groups. Fish fed 1.00 g kg^-1 dietary DE showed significant increase in plasma total protein, complement 4 content and alkaline phosphatase, lysozyme, glutathione reductase (GSR) activity, but significant decrease in triglyceride, low density lipoprotein cholesterol, malondialdehyde (MDA) content and aspartate aminotransferase activities compared to the control group (P < 0.05). Hepatic antioxidant enzymes (SOD, T-AOC, CAT, GSH-Px, GSR) significantly increased whereas MDA content significantly decreased in fish fed 1.00 g kg^-1 DE supplement (P < 0.05). After challenge with Vibrio harveyi, significant higher post-challenge survival was observed in fish fed DE supplement (P < 0.05). These results indicated that golden pompano fed a diet supplemented with DE (especially at 1.00 g kg^-1 of fed supplement) could significantly promote its growth performance, feed utilization, body protein deposit, immune ability, hepatic and plasma antioxidative enzyme activities and improve its resistance to infection by Vibrio harveyi.

Vitamin E deficiency depressed fish growth, disease resistance, and the immunity and structural integrity of immune organs in grass carp (Ctenopharyngodon idella): Referring to NF-κB, TOR and Nrf2 signaling

This study investigated the effects of dietary vitamin E on growth, disease resistance and the immunity and structural integrity of head kidney, spleen and skin in grass carp (Ctenopharyngodon idella). The fish were fed six diets containing graded levels of vitamin E (0, 45, 90, 135, 180 and 225 mg/kg diet) for 10 weeks. Subsequently, a challenge test was conducted by injection of Aeromonas hydrophila. The results showed that compared with optimal vitamin E supplementation, vitamin E deficiency caused depressed growth, poor survival rates and increased skin lesion morbidity in grass carp. Meanwhile, vitamin E deficiency decreased lysozyme and acid phosphatase activities, complement component 3 and complement component 4 contents in the head kidney, spleen and skin of grass carp (P < 0.05). Moreover, vitamin E deficiency down-regulated antimicrobial peptides (Hepcidin, liver-expressed antimicrobial peptide-2A, -2B, β-defensin), IL-10, TGFβ1, IκBα, TOR and S6K1 mRNA levels (P < 0.05) and up-regulated IL-1β, IL-6, IL-8, IFN-γ2 and TNFα, NF-κB p65, IKKα, IKKβ and 4EBP1 (not in the head kidney) mRNA levels (P < 0.05). In addition, vitamin E deficiency caused oxidative damage, decreased superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and glutathione reductase (GR) activities, and down-regulated the mRNA levels of antioxidant enzymes and signaling molecules Nrf2 (P < 0.05). Vitamin E deficiency also induced apoptosis by up-regulating capase-2, -3, -7, and -8 mRNA levels in the head kidney, spleen and skin of grass carp. In conclusion, this study indicated that dietary vitamin E deficiency depressed fish growth, impaired the immune function and disturbed the structural integrity of the head kidney, spleen and skin in grass carp, but optimal vitamin E supplementation can reverse those negative effects in fish. The optimal vitamin E requirements for young grass carp (266.39-1026.63 g) to achieve optimal growth performance and disease resistance based on the percent weight gain (PWG) and skin lesion morbidity were estimated to be 116.2 and 130.9 mg/kg diet, respectively. Meanwhile, based on immune indicator (LA activity in the head kidney) and antioxidant indicator (protection of spleen against MDA), the optimal vitamin E requirements for young grass carp were estimated to be 123.8 and 136.4 mg/kg diet, respectively.

Priming the immune system of Penaeid shrimp by bacterial HSP70 (DnaK)

This study was conducted to test the effect of DnaK on priming immune responses in Penaeid shrimp. Juvenile-specific pathogen-free (SPF) P. vannamei shrimp were injected with 0.05 μg recombinant DnaK. One hour post-DnaK priming, a non-lethal dose of Vibrio campbellii (10(5) CFU shrimp(-1)) was injected. Other treatments include only DnaK or V. campbellii injection or control with blank inocula. The haemolymph of three shrimp from each treatment was collected at 1.5, 6, 9 and 12 h post-DnaK priming (hpp). It was verified that injection with DnaK and V. campbellii challenge affected the transcription of 3 immune genes, transglutaminase-1 (TGase-1), prophenoloxidase-2 (proPO-2) and endogenous HSP70 (lvHSP70). In P. monodon, shrimp were first injected with DnaK at a dose of 10 μg shrimp(-1) and one hour later with 10(6) CFU of V. harveyi (BB120) shrimp(-1). Shrimp injected with DnaK showed a significant increase in proPO expression compared to the control (P < 0.05). Yet a double injection (DnaK and Vibrio) seemed to cause an antagonistic response at the level of expression, which was not equalled at the level of PO activity. Those results suggest that DnaK is able to modulate immune responses in P. vannamei and P. monodon.

Dietary administration of Gynura bicolor (Roxb. Willd.) DC water extract enhances immune response and survival rate against Vibrio alginolyticus and white spot syndrome virus in white shrimp Litopeneaus vannamei

Gynura bicolor (Roxb. & Willd.) DC., a perennial plant belonging to the Asteraceae family, is originated from the tropical area of Asia. The total hemocyte count (THC), phenoloxidase (PO) activity, respiratory bursts (RBs), superoxide dismutase (SOD) activity, and lysozyme activity were examined after white shrimp Litopenaeus vannamei had been fed diets containing the water extract of G. bicolor at 0 (control), 0.5, 1.0, and 2.0 g (kg diet)(-1) for 7-28 days. The results indicated that these parameters increased accordingly with the amount of extract and time. THCs of the shrimp fed the G. bicolor diets at 1.0 and 2.0 g (kg diet)(-1) were significantly higher than that fed the control diet for 14-28 days. For the shrimp fed the G. bicolor diets at 0.5, 1.0, and 2.0 g (kg diet)(-1), the PO, RBs, and lysozyme activities reached the highest levels after 7 days, whereas SOD activity reached the highest levels after 14 days. In a separate experiment, white shrimp L. vannamei fed the diets containing the G. bicolor extract for 28 days were challenged with Vibrio alginolyticus at 3 × 10(6) cfu shrimp(-1) and white spot syndrome virus (WSSV) at 1 × 10(3) copies shrimp(-1). The survival rate of the shrimp fed the G. bicolor diets was significantly higher than that of the shrimp fed the control diet at 48-144 h post challenge V. alginolyticus and WSSV. For the shrimp fed the G. bicolor diets at 0.5, 1 and 2 g (kg diet)(-1) under challenges of V. alginolyticus and WSSV, their LPS- and β-1,3-glucan-binding protein (LGBP) and peroxinectin (PE) mRNA expressions were significantly higher than those of the challenged control shrimp at 12-96 and 24-144 h post-challenge, respectively. We concluded that dietary administration of a G. bicolor extract could enhance the innate immunity within 28 days as evidenced by the increases in immune parameters (PO, RBs, and lysozyme) and antioxidant enzyme (SOD) activities of shrimp to against V. alginolyticus and WSSV infections.