Immune Response Of Common Carp Research Articles

Immune responses to bacterial infection in zebrafish juveniles with different early-life infectious histories

Both systemic and locally released steroid hormones, such as cortisol and estrogens, show immunomodulatory actions. This research gives evidence that circulating and leukocyte-derived estrogens can be involved in the regulation of the immune response in common carp, during homeostasis and upon restraining stress. It was found that stress reduced level of blood 17β-estradiol (E2) and down-regulated the gene expression of components of the “classical” estrogen system: the nuclear estrogen receptors and the aromatase CYP19, in the hypothalamus, the pituitary and in the ovaries. In contrast, higher gene expression of the nuclear estrogen receptors and cyp19a was found in the head kidney of stressed animals. Moreover, stress induced changes in the E2 level and in the estrogen sensitivity at local/leukocyte level. For the first time in fish, we showed the presence of physiologically relevant amounts of E2 and the substrates for its conversion (estrone – E1 and testosterone – T) in head kidney monocytes/macrophages and found that its production is modulated upon stress. Moreover, stress reduced the sensitivity of leukocytes towards estrogens, by down-regulation the expression of the erb and cyp19 genes in carp phagocytes. In contrast, era expression was up-regulated in the head kidney monocytes/macrophages and in PBLs derived from stressed animals. We hypothesize that, the increased expression of ERα, that was observed during stress, can be important for the regulation of leukocyte differentiation, maturation and migration.In conclusion, these results indicate that, in fish, the estrogen network can be actively involved in the regulation of the systemic and local stress response and the immune response.

Immune response of common carp to presporogonic development of myxozoan Sphaerospora molnari

Immune response of common carp to presporogonic development of myxozoan Sphaerospora molnari

The kinetics of cellular and humoral immune responses of common carp to presporogonic development of the myxozoan Sphaerospora molnari

BackgroundSphaerospora molnari is a myxozoan parasite causing skin and gill sphaerosporosis in common carp (Cyprinus carpio) in central Europe. For most myxozoans, little is known about the early development and the expansion of the infection in the fish host, prior to spore formation. A major reason for this lack of information is the absence of laboratory model organisms, whose life-cycle stages are available throughout the year.ResultsWe have established a laboratory infection model for early proliferative stages of myxozoans, based on separation and intraperitoneal injection of motile and dividing S. molnari stages isolated from the blood of carp. In the present study we characterize the kinetics of the presporogonic development of S. molnari, while analyzing cellular host responses, cytokine and systemic immunoglobulin expression, over a 63-day period. Our study shows activation of innate immune responses followed by B cell-mediated immune responses. We observed rapid parasite efflux from the peritoneal cavity (< 40 hours), an initial covert infection period with a moderate proinflammatory response for about 1–2 weeks, followed by a period of parasite multiplication in the blood which peaked at 28 days post-infection (dpi) and was associated with a massive lymphocyte response. Our data further revealed a switch to a massive anti-inflammatory response (up to 1456-fold expression of il-10), a strong increase in the expression of IgM transcripts and increased number of IgM+ B lymphocytes, which produce specific antibodies for the elimination of most of the parasites from the fish at 35 dpi. However, despite the presence of these antibodies, S. molnari invades the liver 42 dpi, where an increase in parasite cell number and indistinguishable outer cell membranes are indicative of effective exploitation and disguise mechanisms. From 49 dpi onwards, the acute infection changes to a chronic one, with low parasite numbers remaining in the fish.ConclusionsTo our knowledge, this is the first time myxozoan early development and immune modulation mechanisms have been analyzed along with innate and adaptive immune responses of its fish host, in a controlled laboratory system. Our study adds important information on host–parasite interaction and co-evolutionary adaptation of early metazoans (Cnidaria) with basic vertebrate (fish) immune systems and the evolution of host adaptation and parasite immune evasion strategies.

Bacterial ghost as delivery vehicles loaded with DNA vaccine induce significant and specific immune responses in common carp against spring viremia of carp virus

Although vaccine is a prophylaxis measure for the contagious and fatal disease caused by spring viremia of carp virus (SVCV), until now, no commercial vaccine is available for worldwide use. To find more effective and safe means for the control of SVCV infection, here, an Escherichia coli DH5α bacterial ghost (DH5α-BG, non-living bacterial) based DNA vaccine delivery system (BG/pEG-G) was constructed. Carp were injected intramuscularly by different treatments (PBS, pEGFP, BG, pEG-G and BG/pEG-G), and the immunoprotective effect induced by these treatments were analyzed. We found a stronger and longer duration immune response (serum antibody production and immune-related genes expression) can be induced in fish vaccinated with BG/pEG-G in comparison with those vaccinated with pEG-G alone. Additionally, a good immune protective effect (relative percentage survival >81.48%) was observed in fish vaccinated with BG/pEG-G vaccine at the dose of 0.2 μg DNA/g of fish. Overall, this study for the first time demonstrates the ability of DH5α-BG as DNA vaccine carrier against SVCV infection in carps, suggesting a practical multivalent strategy for the control of aquatic disease.

Oral immunization with recombinant Lactobacillus casei expressing flaB confers protection against Aeromonas veronii challenge in common carp, Cyprinus carpio

Aeromonas veronii is an important type of gram-negative pathogen of human-livestock-aquatic animal and causes great economic losses in the aquaculture industry. Vaccination is an effective method of defence against A. veronii. There are many factors that restrict the use of vaccination, and the development of new oral vaccines is urgently needed. The selection of suitable antigens is of great significance for the development of aquaculture vaccines. Bacterial flagellin can specifically bind to TLR5 and induce the release of cytokines from the organism, which could be used in the development of vaccines. In this study, we constructed two recombinant Lactobacillus casei (L. casei) (surface-displayed or secretory) expressing the flaB of A. veronii and evaluated the effect of immune responses in common carp. The flaB gene (900 bp) of A. veronii was subcloned into the L. casei expression plasmids pPG-1 (surface-displayed) and pPG-2 (secretory). Western blot and immunofluorescence assays confirmed the expression of the recombinant flaB protein. Common carp immunized with Lc-pPG-1-flaB and Lc-pPG-2-flaB via oral administration route exhibited induction of antibody expression and innate immune responses. The results indicated that Lc-pPG-1-flaB and Lc-pPG-2-flaB can induce high levels of IgM, ACP, AKP, LZM and SOD activity in organisms, and Lc-pPG-1-flaB can induce even higher levels. The recombinant L. casei may effectively induce humoral immunity and increase the serum immunological index. Furthermore, leukocytes phagocytosis percentage and index of the recombinant L. casei were enhanced. The results of qRT-PCR showed that recombinant L. casei can significantly increase the expression of IL-10, IL-β, IFN-γ and TNF-α in the tissues of immunized common carp, compared with control groups. Viable recombinant L. casei strains, which were delivered directly survived throughout the intestinal tract. Common carp that received Lc-pPG-1-flaB (66.7%) and Lc-pPG-2-flaB (53.3%) exhibited higher survival rates than the controls after challenge with the pathogen A. veronii. Our work indicated that Lc-pPG-1-flaB and Lc-pPG-2-flaB had beneficial effects on immune response and enhanced the disease resistance of common carp against A. veronii infection. The combination of flaB delivery and the Lactic acid bacteria (LAB) approach may be a promising method for the development of oral vaccines for treating A. veronii. In future research, we will focus on the colonization ability of LAB in the intestines and on the impact of these bacteria on intestinal flora.

Growth performance, gut morphometry and innate immune profiles of common carp, Cyprinus carpio juveniles fed diet fortified with Mitracarpus scaber leaves extract and its susceptibility to pathogenic bacteria, Aeromonas hydrophila

Mitracarpus scaber, an endemic medicinal plant to Nigeria, Africa, has medicinal value. In the present study, Mitracarpus scaber leaves extract (MSLE) was fed to common carp, Cyprinus carpio to evaluate its effect on growth performance, nutrient utilization, gut morphometry, and innate immunity parameters. Four isonitrogenous diets (32% crude protein) containing 0.0, 5, 10, or 15 g MSLE/kg diet were fed to fish (7.52 ±0.23 g) for 12 weeks. After the feeding trial, fish were exposed to pathogenic bacteria (Aeromonas hydrophila) for 14 days. Growth performance, nutrient utilization, and feed intake were significantly improved with increasing MSLE levels up to 10 g/kg diet. Similarly, fish fed MSLE diets increased significantly intestinal villi length/width, and absorption area. Furthermore, activities of respiratory burst, lysozyme, catalase, and superoxide dismutase were significantly higher in fish fed diets containing MSLE levels, and their highest values were obtained at fish fed 15 g MSLE/kg diet. After bacterial challenge, fish mortality was lowest (8.45 ±1.30%) in fish fed 15 g MSLE/kg diet, whereas highest mortality (52.50 ±4.56%) was observed with fish fed the control diet. The present study conjured that MSLE inclusion in fish diets with optimum level of 10 g/kg diet stimulated significantly the performance, nutrient utilization, modified gut morphometry, and innate immune response of common carp. Also, its inclusion protected fish against pathogenic bacteria, A. hydrophila infection.

Non-specific immune responses and intestinal immunity of common carp (Cyprinus carpio ) fed Jujube (Ziziphus jujube ) fruit extract

This study investigated the effects of Jujube (Ziziphus jujube) fruit extract (JFE) as an excellent source of nutrients and phytochemicals on the innate immune responses and expression of genes involved in intestinal immunity of common carp (Cyprinus carpio) fingerlings. Three hundred healthy carps (10.78 ± 0.05 g) fingerlings were randomly allocated to 12 fibre glass tanks (300L; 15 fish per tank) and fed for 8 weeks with experimental diets which contained different levels of JFE (0%, 0.25%, 0.5%, or 1%). Thereafter, serum non-specific immune parameters [total immunoglobulin (Ig) as well as alternative complement (ACH50) and lysozyme activity (SL)] and expression of genes involved in intestinal immunity (lyz, tnf-alpha, il1b, il8, il10, and tgfb) were measured. The results revealed a significant elevation of Ig level in the JFE-fed fish (p < 0.05) over the control fish. However, there was no significant difference among treated groups in case of serum total Ig. The highest levels of SL and ACH50 were observed in fish fed 1% of JFE. Nonetheless, no significant difference was noticed regarding SL and ACH50 of control and other supplemented groups (0.25% and 0.5% JFE). Also, expression of lyz, tnf-alpha, and il1b genes increased significantly (p < 0.05) in JFE-fed fish, in a dose-dependent manner. On the other hand, significant (p < 0.05) down-regulation of il110 and tgfb were noticed in treated groups. The present findings suggested that extraction of Jujube, Z. jujube fruit, possesses beneficial effects on immune responses of common carp.

Serum immune responses in common carp (Cyprinus carpio L.) to paraquat exposure: The traditional parameters and circulating microRNAs

Paraquat (PQ) is a herbicide used worldwide, and it was shown to be a high-risk compound to aquatic organisms. This study was conducted to investigate the effects of PQ on traditional serum parameters and circulating microRNAs (miRNAs) in common carp to further elucidate the mechanism of PQ toxicity in fish. In the current study, a subacute toxicity test of common carp exposed to PQ at 1.596 and 3.192 mg/L for 7 d was conducted under laboratory conditions. The results showed that PQ exposure generally reduced the levels of T-AOC, SOD, CAT, and GST, but significantly increased MDA levels in the serum, indicating that PQ exposure induces oxidative stress and lipid peroxidation in the fish. The results of biochemical assays showed that PQ exposure not only significantly altered the activities of LDH, AST, ALT, ACP, AKP, and lysozyme and the contents of IgM and complement 3 but also promoted the expression of pro-inflammatory cytokines, including IFN-γ, IL-1β, IL-6, IL-8, and TNF-α. Additionally, PQ inhibited the levels of the anti-inflammatory cytokines IL-10 and TGF-β, suggesting that PQ exposure may cause fish tissue injury and promote immune inflammatory responses. Furthermore, we found that serum circulating miRNAs, such as ccr-mir-122, ccr-mir-125b, ccr-mir-146a, and ccr-mir-155, were generally promoted in fish following PQ exposure. Based on our results and reports on miRNA-based diagnosis of tissue damage and inflammatory responses in mammals, we suggest that serum ccr-mir-122, ccr-mir-125b, ccr-mir-146a, and ccr-mir-155 could be new biomarkers of PQ toxicity in fish.

Immunogene expression in head kidney and spleen of common carp (Cyprinus carpio L.) following thermal stress and challenge with Gram-negative bacterium, Aeromonas hydrophila

To evaluate the effect of thermal and microbial stress on the immune response of common carp (Cyprinus carpio L.), relative mRNA expression level of pro-inflammatory cytokines [tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β] and other genes related to immune or stress response [inducible nitric oxide synthase (iNOS), heat shock protein 70 (Hsp70), superoxide dismutase one (SOD1), and glucocorticoid receptor (GR)] was measured by quantitative PCR (qPCR). In addition, total protein and total immunoglobulin level in blood plasma of experimental common carp was also assayed. All the above parameters were estimated 24 h post-challenge with Gram-negative bacterium, Aeromonas hydrophila. Common carp (54.89 ± 6.90 g) were initially exposed to 20 °C (control group) and 30 °C (thermal stress group) water temperature for 30 days, followed by experimental challenge with 2.29 × 108 colony forming unit/mL (CFU/mL; LD50 dose) of A. hydrophila. Exposure of fish to thermal stress and subsequently challenge with A. hydrophila significantly (P < 0.05) increases the IL-1β mRNA expression in head kidney and spleen of common carp by ~ 39.94 and ~ 4.11-fold, respectively. However, TNF-α mRNA expression in spleen decreased ~ 5.63-fold in control fish challenged with A. hydrophila. Thermal stress and challenge with bacterium suppresses the iNOS and GR mRNA expression in spleen of common carp. Moreover, significant (P < 0.05) increase in total protein content of blood plasma (~ 43 mg/g) was evident in fish exposed to thermal stress and challenged with A. hydrophila. In conclusion, our study highlights the importance of elevated temperature stress and microbial infection in differential regulation of expression of several immunogenes in common carp.

Stress differentially affects the systemic and leukocyte estrogen network in common carp

Both systemic and locally released steroid hormones, such as cortisol and estrogens, show immunomodulatory actions. This research gives evidence that circulating and leukocyte-derived estrogens can be involved in the regulation of the immune response in common carp, during homeostasis and upon restraining stress. It was found that stress reduced level of blood 17β-estradiol (E2) and down-regulated the gene expression of components of the “classical” estrogen system: the nuclear estrogen receptors and the aromatase CYP19, in the hypothalamus, the pituitary and in the ovaries. In contrast, higher gene expression of the nuclear estrogen receptors and cyp19a was found in the head kidney of stressed animals. Moreover, stress induced changes in the E2 level and in the estrogen sensitivity at local/leukocyte level. For the first time in fish, we showed the presence of physiologically relevant amounts of E2 and the substrates for its conversion (estrone – E1 and testosterone – T) in head kidney monocytes/macrophages and found that its production is modulated upon stress. Moreover, stress reduced the sensitivity of leukocytes towards estrogens, by down-regulation the expression of the erb and cyp19 genes in carp phagocytes. In contrast, era expression was up-regulated in the head kidney monocytes/macrophages and in PBLs derived from stressed animals. We hypothesize that, the increased expression of ERα, that was observed during stress, can be important for the regulation of leukocyte differentiation, maturation and migration.In conclusion, these results indicate that, in fish, the estrogen network can be actively involved in the regulation of the systemic and local stress response and the immune response.

Molecular characterization and expression pattern of X box-binding protein-1 (XBP1) in common carp (Cyprinus carpio L.): Indications for a role of XBP1 in antibacterial and antiviral immunity

X box-binding protein-1 (XBP1) is a transcription factor that is essential for the unfolded protein response (UPR) and the differentiation of plasma cells, and some findings have also uncovered its function in innate immunity. XBP1 typically has two different transcripts, un-spliced (XBP1u) and spliced forms (XBP1s), but XBP1s is an active transcription factor in the regulation of target genes. To date, there is no evidence about the identification and function of XBP1 in common carp. Moreover, no data are currently available regarding the role of fish XBP1 in innate immunity. Thus, to determine whether XBP1 is involved in innate immune response in common carp, we cloned CcXBP1s and examined the expression of XBP1s and a XBP1s stimulated gene (IL-6) after Aeromonas hydrophila (A. hydrophila) and polyinosinic-polycytidylic acid (polyI:C) challenges. The results imply that CcXBP1s, as an active transcription factor, might play regulation roles in the antibacterial and antiviral innate immune responses of common carp. This allows us to gain new insights into the immunological function of XBP1 in fish innate immunity and the evolution of this important class of genes across vertebrates.

Effect of Praziquantel on Hemato-Immunological Indices in Common Carp (Cyprinus carpio)

Praziquantel (PZQ) has been used for treatment of fish parasites for a long time. However, limited investigations exist implying its immunomodulatory properties in fish species. In the present study, the effects of bath administration of therapeutic doses of PZQ on immune responses of common carp, Cyprinus carpio, were investigated. Fingerlings of C. carpio were given 24-h bath immersion in 0.5, 1.5 and 5 mg/l PZQ solutions, and the immune responses were assessed on 1, 7, 14, 21 and 28 days post-PZQ administration in comparison with the controls. Data revealed that the medium and high doses (1.5 and 5 mg/l, respectively) significantly (p < 0.05) enhanced some specific and non-specific immune parameters namely specific antibody titer, serum lysozyme and bactericidal activities, phagocytic and respiratory burst activities, disease resistance, total plasma protein and immunoglobulin level. This study provides preliminary evidence for immunomodulatory properties of PZQ in fish and its potential capacity as an immunostimulant in common carp.

Effect of dietary soybean lecithin on growth parameters, digestive enzyme activity, antioxidative status and mucosal immune responses of common carp (Cyprinus carpio)

Effect of dietary soybean lecithin on growth parameters, digestive enzyme activity, antioxidative status and mucosal immune responses of common carp (<i>Cyprinus carpio</i>)

Effect of T-2 toxin-contaminated diet on common carp (Cyprinus carpio L.)

The T-2 toxin, a fungal metabolite produced by Fusarium molds, occurs in a range of agriculture products. Reduced availability of fish meal has led to increasing use of cereals as a source of protein in commercial aquaculture feeds, which has increased the potential for mycotoxin contamination. The purpose of this study was to investigate toxicity of T-2 toxin intake in common carp (Cyprinus carpio L.) using haematological, biochemical and immunological parameters and oxidative stress indices. In a four-week feeding trial, fish were fed a commercial diet with 5.3 mg/kg T-2 toxin added. Ingestion of contaminated diet did not lead to mortality of fish, probably due to lower feed intake. On the other hand, it significantly affected haematological variables such as haematocrit, haemoglobin, red blood cell counts leading to anemia and white blood cell counts leading to leukopenia due to lymphopenia. Plasma glucose concentration and alanine amino transferase activity showed a significant increase while triglycerides concentration decreased. Activity of ceruloplasmin was significantly decreased in plasma. Further, liver glutathione S-transferase activity was significantly increased and catalase activity decreased, in parallel with a significant increase in caudal kidney catalase activity and a decrease in glutathione peroxidase activity. Finally, lipid peroxidation (detected as malondialdehyde) was significantly increased in the liver and caudal kidney. Changes in non-specific immune response and cytokine levels in head kidney indicated immune system sensitivity to T-2 toxin. Overall, the results demonstrate that this feed-borne mycotoxin is able to induce anaemia and oxidative stress and cause changes in the immune response of common carp.

Aqueous extract of Heracleum persicum Desf. enhances immune response of common carp, Cyprinus carpio, and protection against Aeromonas hydrophila

Aqueous extract of Heracleum persicum Desf. enhances immune response of common carp, Cyprinus carpio, and protection against Aeromonas hydrophila

Transciptomic study of mucosal immune, antioxidant and growth related genes and non-specific immune response of common carp (Cyprinus carpio) fed dietary Ferula (Ferula assafoetida).

A 8-weeks feeding trial was conducted to examine the effects of different levels (0, 0.5, 1 and 2%) of dietary Ferula (Ferula assafoetida) on expression of antioxidant enzymes (GSR, GPX and GSTA), immune (TNF-alpha, IL1B, IL- 8 and LYZ) and growth (GH, IGF1 and Ghrl) genes as well as cutaneous mucus and serum non-specific immune response in common carp. The results revealed Ferula significantly increased antioxidant gene expression (GSR and GSTA) in a dose dependent manner (P<0.05). The expression of immune growth related genes were significantly higher in Ferula fed fish compared control group (P<0.05). The effects of Ferula on expression of genes was more pronounced in higher doses. Feeding on Ferula supplemented diet remarkably increased skin mucus lysozyme activity (P<0.05). However, evaluation of mucus total Ig and protease activity revealed no significant difference between control and treated groups (P>0.05). Regarding non-specific humoral response, serum total Ig, lysozyme and ACH50 showed no remarkable variation between Ferula fed carps and control group (P>0.05). These results indicated up-regulation of growth and health related genes in Ferula fed common carp. Further studies using pathogen or stress challenge is required to conclude that transcriptional modulation is beneficial in common carp.

Occurrence of glucocorticoids discharged from a sewage treatment plant in Japan and the effects of clobetasol propionate exposure on the immune responses of common carp (Cyprinus carpio) to bacterial infection.

The present study evaluated the environmental risks to common carp (Cyprinus carpio) posed by glucocorticoids present in sewage treatment plant (STP) effluent. To gather information on the seasonal variations in glucocorticoid concentration, the authors sampled the effluent of a Japanese STP every other week for 12 mo. Six of 9 selected glucocorticoids were detected in the effluent, with clobetasol propionate and betamethasone 17-valerate detected at the highest concentrations and frequencies. The present study's results indicated that effluent glucocorticoid concentration may depend on water temperature, which is closely related to the removal efficiency of the STP or to seasonal variations in the public's use of glucocorticoids. In a separate experiment, to clarify whether glucocorticoids in environmental water increase susceptibility to bacterial infection in fish, the authors examined the responses to bacterial infection (Aeromonas veronii) of common carp exposed to clobetasol propionate. Clobetasol propionate exposure did not affect bacterial infection-associated mortality. In fish infected with A. veronii but not exposed to clobetasol propionate, head kidney weight and number of leukocytes in the head kidney were significantly increased (p < 0.05), whereas these effects were not observed in infected fish exposed to clobetasol. This suggests that clobetasol propionate alleviated bacterial infection-associated inflammation. Together, these results indicate that susceptibility to bacterial infection in common carp is not affected by exposure to glucocorticoids at environmentally relevant concentrations.

Enhancement of secondary metabolites from Bacillus Licheniformis XY-52 on immune response and expression of some immune-related genes in common carp, Cyprinus carpio

This study was undertaken to isolate active secondary metabolites from immunostimulatory Bacillus Licheniformis XY-52 and evaluate their activities at 0%, 0.5%, 1.0%, and 2.0% doses supplementation with feed on immune response in common carp at weeks 1, 2, and 3. By applying chromatography techniques and successive recrystallization, two purified metabolites were obtained and identified by spectral data (mass spectrometry and nuclear magnetic resonance) as: Cyclo-(Phe–Tyr) and Cyclo-(Phe–Gly). The results revealed that humoral innate immune parameters (lysozyme activity, phagocytic activity and bactericidal activity) were significantly (P < 0.05) increased after feeding on the two active compounds-supplemented diet. Furthermore, administration of the two active compounds significantly (P < 0.05) up regulated IL-1β, Type 1 IFN, IFN g2b, IL10 and TNF-α gene expression. Heat shock protein 70 (HSP70) gene expression was significantly (P < 0.05) lower as compared to control group at the end of trial. Common carp fed with the two compounds had higher survival rates (69.3%) compared to the controls (32.0%) after challenged with the pathogen, Aeromonas hydrophila. The present study indicates that the two isolated active compounds could positively influence immune response and enhance disease resistance of common carp against A. hydrophila infection.

Poly D, L-lactide-co-glycolic Acid (PLGA)-encapsulated CpG-oligonucleotide (ODN) on Immune Response in Cyprinus carpio against Aeromonas hydrophila

The effect of Poly D, L-lactide-co-glycolic acid (PLGA) encapsulated ODN 1668 nanospheres (NS) on innate and adaptive immune response in common carp, Cyprinus carpio against Aeromonas hydrophila is reported. PLGAencapsulated ODN biodegradable NS did not have a significant impact on particle size as expected of the particles was clearly positive for non-coated and coated PLGA/ODN NS. The myeloperoxidase (MPO) activity and serum haemolysin titre significantly increased in fish injected with ODN 1668 and PLGA-encapsulated ODN 1668 groups on week 4 whereas the respiratory burst (RB) activity significantly increased when administered with ODN 1668 and PLGA-encapsulated ODN 1668 (PLGA-ODN 1668) from weeks 1 to 4. The haemoagglutinating titre was significantly enhanced in PLGA-encapsulated ODN 1668 group on week 2 while in ODN 1668 and PLGA-encapsulated ODN 1668 groups the increase manifested on week 4. The bacterial agglutination titre significantly increased in ODN 1668 and PLGA-encapsulated ODN 1668 groups on weeks 2 and 4. The cumulative mortality in ODN 1668 and PLGAencapsulated ODN 1668 groups were 10% each whereas it was 15% in PLGA group. This study indicates that single administration of PLGA-encapsulated ODN 1668 nanospheres elicits better immune response than PLGA or ODN 1668 alone in C. carpio against A. hydrophila.

The dietary wood betony, Stachys lavandulifolia Vahl extract as a growth promoter and immune enhancer in common carp (Cyprinus carpio).

The present study was conducted to evaluate the efficacy of wood betony (WB), Stachys lavandulifolia extract on growth performance and some immune responses in common carp, Cyprinus carpio. Different concentrations of the WB extract 0, 2, 4 and 8% (g per 100 g of diet) were added to commercial diet. Each treatment was randomly assigned to triplicate groups of fish having average initial weight of 44 ± 0.62 g for 10 weeks. The results showed that final weight, food conversion ratio, specific growth rate and condition factor were significantly improved by WB in a dose dependent manner, where the best growth parameters were achieved in the group of fish receiving the highest concentration of WB (P<0.05). Feeding fish at 2 and 4% W/W by WB in the diet improved lysozyme activity, ACH50 and IgM levels significantly in comparison to the control (P<0.05). Group of fish fed on 4% WB in the diet had the best levels of the immune characteristics (P<0.05). Based on the results of this study, it is recommended to feed common carp with WB to improve growth and non-specific immunity.