Non-specific Immune Parameters Research Articles

Streptomyces kunmingensis XK9 and galactooligosaccharide synergistically enhance growth performance, nonspecific immunity and disease resistance in striped catfish (Pangasianodon hypophthalmus)

Abstract The present study evaluated the effectiveness of the synergy of Streptomyces kunmingensis XK9 and galactooligosaccharides (GOS) in improving growth performance, nonspecific immunity, and protection of striped catfish (Pangasianodon hypophthalmus). Seven feed regimens were tested in striped catfish fingerlings, including commercial pellets supplemented with preparations S7, S8, and S9 containing XK9 at 107 CFU/mL, 108 CFU/mL, and 109 CFU/mL, respectively; G5 containing 5% GOS; S7G5, S8G5, and S9G5 including 5% GOS and XK9 at different doses of 107 CFU/mL, 108 CFU/mL, and 109 CFU/mL, respectively. After 3 months of treatment with different dietary regimens, weight gain, specific growth rate, weight gain rate, and feed conversion ratio were greatly improved in fish-fed diets containing S9, S8G5, and S9G5 (p<0.05). Nonspecific immune parameters, including total white blood cell, phagocytic activity, and phagocytic index, increased consistently in fish that were fed diets containing synbiotics S8G5 and S9G5 (p<0.05). Lysozyme and complement activity increased substantially in fish that were fed diets supplemented with S9G5 (p<0.05). The protective effect of XK9 and GOS on striped catfish was evaluated after 15 days of challenge with Edwardsiella ictaluri. The results achieved show that the cumulative mortality rate sharply decreased in fish fed a diet containing the synbiotic S9G5, down 2.17 times compared to the control group; pathogen density was lowest in tanks of fish that were fed regimens containing S8G5, S9G5, and S9 (p<0.05). The results suggest that synbiotics, including S. kunmingensis XK9 and GOS, have the potential to be applied in sustainable farming for the striped catfish industry.

Copaiba oil’s bactericidal activity and its effects on health and zootechnical performance for Nile tilapia after oral supplementation

Tilapia is one of the most important farmed fish in the world and the most cultivated in Brazil. The increase of this farming favors the appearance of diseases, including bacterial diseases. Therefore, the aim of this study was to evaluate the bactericidal activity of copaiba oil, Copaifera duckei, against Streptococcus agalactiae and Flavobacterium columnare and the dietary effect of copaiba oil on zootechnical performance, hematological, biochemical, immunological, and histological analysis before and after an intraperitoneal infection (body cavity) with S. agalactiae in Nile tilapia. For this, fish were randomly distributed into 15 fiber tanks in five treatments (0, 0.25, 0.50, 0.75, and 1.0%) and fed with a commercial diet supplemented with copaiba oil for 30 days. After this period, the fish were randomly redistributed for the experimental challenge with S. agalactiae into six treatments (T0, T1, T2, T3, T4, and T5), the fish were anesthetized, and blood samples were collected to assess hematological, biochemical, immunological, and histological parameters. Copaiba oil showed bactericidal activity against Streptococcus spp. and Flavobacterium spp. in vitro. In addition, concentrations of 0.75 and 1.0% of copaiba oil have an anti-inflammatory effect and improve hematological and immunological parameters, increasing leukocyte numbers, albumin, and serum lytic activity. Furthermore, there is an increase in the intestinal villus length and tissue damage in groups at concentrations of 0.75 and 1.0% of copaiba oil. In conclusion, copaiba oil presented bactericidal activity against Streptococcus spp. and Flavobacterium spp. in vitro, and oral supplementation at concentrations of 0.75 and 1.0% compared to the control group enhanced non-specific immune parameters and digestibility in Nile Tilapia.

Anti-parasitic activity of garlic (Allium sativum) and onion (Allium cepa) extracts against Dactylogyrus spp. (Monogenean) in Nile tilapia (Oreochromis niloticus): Hematology, immune response, histopathological investigation, and inflammatory cytokine genes of gills

BackgroundGills monogenean infestation causes significant mortalities in cultured fishes as a result of respiratory manifestation. Medicinal plants are currently being heavily emphasized in aquaculture due to their great nutritional, therapeutic, antimicrobial activities, and financial value.MethodsThe current study is designed to assess the effect of garlic (Allium sativum) and onion (Allium cepa) extracts as a water treatment on the hematological profile, innate immunity, and immune cytokines expression besides histopathological features of gills of Nile tilapia (Oreochromis niloticus L.) infected with gills monogenetic trematodes (Dactylogyrus sp.). Firstly, the 96-hour lethal concentration 50 (96 h-LC50) of garlic extract (GE) and onion extract (OE) were estimated to be 0.4 g/ L and 3.54 g/ L for GE and OE, respectively. Moreover, the in-vitro anti-parasitic potential for (GE) was found between 0.02 and 0.18 mg/mL and 0.4 to 1.8 mg/mL for OE. For the therapeutic trial, fish (n = 120; body weight: 40–60 g) were randomly distributed into four groups in triplicates (30 fish/group, 10 fish/replicate) for 3 days. Group1 (G1) was not infected or treated and served as control. G2 was infected with Dactylogyrus spp. and not exposed to any treatment. G3, G4 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of OE, respectively. G5, G6 were infected with Dactylogyrus sp. and treated with 1/10 and 1/5 of 96 h LC50 of GE, respectively.ResultsNo apparent signs or behaviors were noted in the control group. Dactylogyrus spp. infected group suffered from clinical signs as Pale color and damaged tissue. Dactylogyrus spp. infection induced lowering of the hematological (HB, MCH, MCHC and WBCs), and immunological variables (lysozyme, nitric oxide, serum Anti- protease activities, and complement 3). the expression of cytokine genes IL-ß and TNF-α were modulated and improved by treatment with A. sativum and A. cepa extracts. The obtained histopathological alterations of the gills of fish infected with (Dactylogyrus spp.) were hyperplasia leading to fusion of the gill filament, lifting of epithelial tissue, aneurism and edema. The results indecated that G4 and G5 is more regenarated epithelium in compare with the control group.ConclusionA. sativum and A. cepa extracts enhance the blood profile and nonspecific immune parameters, and down-regulated the expression level of (IL-1β and TNF-α).

Effect of dietary mannan oligosaccharide inclusion on production parameters of Farfantepenaeus aztecus cultured in a biofloc system

AbstractThe effects of dietary mannan oligosaccharide (MOS) supplementation in a biofloc system on growth performance, whole‐body proximate composition, whole‐body fatty acids, nonspecific immune parameters, antioxidant enzyme activities, digestive enzyme activity, and gut microbiota of brown shrimp, Farfantepenaeus aztecus, were investigated. Shrimp were fed five diets containing different levels of MOS doses (MOS0: basal diet, MOS1: 0.1%, MOS2: 0.2%, MOS3: 0.3%, and MOS4: 0.4%) during the 90‐day trial. The results indicated that all MOS‐supplemented shrimp showed significantly higher growth rates and better feed utilization than shrimp fed the control diet. Experimental diets had varying effects on the nonspecific immune parameters and antioxidant enzyme activities, indicating that MOS supplementation resulted in significant differences in the parameters except for respiratory burst activity. Significantly higher protease activity was observed in shrimp fed MOS1 and MOS2 diets compared with MOS0, MOS3, and MOS4 diets. Shrimps fed MOS2 and MOS3 diets had the highest lipase and amylase activities among all groups. Proteobacteria were the most abundant phylum in all groups and were higher at increasing MOS doses. In conclusion, these results suggest that supplementing the diet of brown shrimp in the biofloc system with 3 g kg−1 of MOS may improve production parameters.

Mannan oligosaccharide improves antioxidant capacity, non-specific immunity and protection against Vibrio disease and Typhoon stress in Trachinotus ovatus juveniles

This study examined the impact of varying doses of mannan oligosaccharide (MOS) supplementation on antioxidant defense, non-specific immunity, resistance to typhoon stress, and resistance to disease in Trachinotus ovatus. Fish groups C, M1, M2, and M3 were fed 1%, 0.3%, 0.6%, and 1% MOS-supplemented feed, respectively. On the 28th and 56th day of the feeding trial, samples from all groups were taken to measure the antioxidant and non-specific immunity parameters and challenged with Vibrio harvey. On the 32nd day, a typhoon hit the experimental site, and the survival rates of all groups were calculated. Results showed that on the 28th day, groups M2 and M3 showed considerably higher levels of antioxidant abilities (T-AOC), and groups M1 and M2 showed significantly enhanced non-specific immunity (AKP, LZM, and TP) levels than those of group C (p < 0.05). All MOS groups had significantly lower cumulative mortality following the challenge test and typhoon stress than the control group (p < 0.05). On the 56th day, groups M2 and M3 showed significantly enhanced antioxidant ability (CAT) compared to the control group. Only one non-specific immunity parameter increased significantly in groups M2 and M3 (p < 0.05). After the challenge test, only group M3 exhibited a significantly declined cumulative mortality rate compared to the control groups (p < 0.05). In summary, supplementation of MOS at dose 0.6% (M2) for 28 days showed the best overall improving effects on the antioxidant capacity, non-specific immunity, disease resistance, and typhoon stress resistance in T. ovatus juveniles.

Effects of 2,4-dichlorophenol on non–specific immunity, histopathological lesions, and redox balance in African Catfish, clarias gariepinus (Burchell, 1822)

ABSTRACT The toxic effects of 2, 4-dichlorophenol (2, 4-DCP) on aquatic organisms are well-established; however, the details regarding the mechanisms underlying the toxicity, especially immunotoxicity are poorly understood. Consequently, the aim of this study was to investigate the histopathologic, oxidative stress and immunotoxic effects attributed to exposure to sublethal concentrations of 2,4-DCP in the African catfish, Clarias gariepinus. Juvenile C. gariepinus were exposed to 0.4, 0.8, or 1.6 mg/L 2, 4-DCP for 28 days after which blood and head kidney were extracted for the determination of various nonspecific innate immune parameters while the liver was excised for histopathology examination and measurement of oxidative stress biomarkers. Control fish were maintained in water spiked 10 µL/L ethanol, representing the solvent control. A significant increase was noted in the activities of lactate dehydrogenase and superoxide dismutase as well as in levels of lipid peroxidation and DNA fragmentation in a dose-dependent manner, with higher adverse effects observed at the highest concentration tested (1.6 mg/L). The total white blood cells (WBC) count was significantly elevated in fish exposed to 2,4-DCP compared to control. Myeloperoxidase content was decreased significantly in fish exposed to 2,4-DCP especially at the highest concentration (1.6 mg/L) compared to controls. The respiratory burst activity did not differ markedly amongst groups. Histopathological lesions noted included edema, leucocyte infiltration, and depletion of hemopoietic tissue in the head kidney of exposed fish. There was significant upregulation in the mRNA expression of tumor necrosis factor (TNF-α) and heat shock protein 70 (HSP 70) but downregulation of major histocompatibility complex 2 (MHC 2) in exposed fish. Data demonstrated that exposure to 2,4-DCP resulted in histopathological lesions, oxidative stress, and compromised immune system in C. gariepinus.

Dietary Artemisia arborescens Supplementation Effects on Growth, Oxidative Status, and Immunity of Gilthead Seabream (Sparus aurata L.).

Fish infectious diseases are one of the main constraints of the aquaculture sector. The use of medicinal plants provides a sustainable way of protection using safe, eco-friendly compounds in a more cost-effective way of treatment, compared to antibiotics. The aim of the present study is the assessment of Artemisia arborescens (AA) feed-supplementation effects on gilthead seabream (Sparus aurata). Fish with an average initial body weight of 109.43 ± 3.81 g, were divided into two groups based on AA feed composition (A25 and A50). Following two months of ad libitum feeding, the effect of diets on fish weight and length were measured. Fish serum and mucus were analyzed for non-specific immune parameters (nitric oxide, lysozyme, myeloperoxidase, protease-/anti-protease activity, and complement), antibody responses, oxidative stress (cytochrome P450 1A1, metallothionein), and metabolism markers (total protein, alkaline phosphatase, and glucose). Expression levels of antioxidants (sod1, gpx1), cytokines (il-1b, il-10, tfgb1, and tnfa), hepcidin, and heat shock protein grp75 genes were measured in spleen samples. A results analysis indicated that A. arborescens use as a feed supplement has a compromised positive effect on the growth performance, immune response, and blood parameters of gilthead seabream. Overall, the suitability of A. arborescens as an efficient food supplement for gilthead seabream health improvement was investigated, setting the basis for its application assessment in Mediterranean aquaculture.

Terminalia arjuna Bark Powder as a Potential Immunomodulator in Labeo rohita: Enhanced Hematological, Adaptive, and Humoral Responses against Bacterial Pathogens and Concordant Liver Histomorphology.

This study investigated the dietary immunomodulatory effects of Terminalia arjuna bark powder (TABP) in Labeo rohita, a freshwater fish model. Four iso-nitrogenous and iso-caloric diets containing graded levels of TABP (0, 1, 10, and 15 g/kg were fed to fish for 90 days, followed by a 10 day challenge with pathogenic bacteria Aeromonas hydrophila and Edwardsiella tarda. An integrated biomarker response (IBR) approach assessed the impact of TABP on hematological, adaptive, and humoral immune parameters, along with liver histomorphology. Dietary TABP at 10 g/kg significantly enhanced (p < 0.05) hematological indices (hemoglobin, red blood cell count, hematocrit), specific immune parameters (lysosomal enzyme activity, phagocytosis, respiratory burst), and non-specific immune parameters (serum lysozyme, alternative complement activity), and exhibited improvements in liver architecture consistent with the enhanced immune response. Broken line regression analysis showed 11.5 g/kg to be an optimum dose. However, at 15 g/kg, a compromised trend was observed in some parameters. These findings suggest an optimal dosage range for TABP's immunomodulatory effects. The study highlights the potential of TABP as a natural immunomodulator in fish aquaculture. The improved immune response and concomitant liver health observed in Labeo rohita opens avenues for further research on TABP's applicability in animal health, using fish as a model organism. Additionally, the IBR approach proved effective in evaluating TABP's immunomodulatory properties, paving the way for similar studies on other natural products in aquaculture.

RNA interference confirmed a close association of CYP, ApD, and UCH with the function of CpG ODNs in Litopenaeus vannamei

CpG oligonucleotides (CpG ODNs) have been demonstrated to enhance the innate immune response in various organisms, including Litopenaeus vannamei, a species of significant economic importance. However, the precise mechanism or the genetic factors of CpG ODNs underlying function in L. vannamei remained elusive. Our previous experiment has identified five potential marker genes, including cytochrome P450 (CYP), gamma-butyrobetaine dioxygenase (γ-BDO), apolipoprotein D (ApD), prostaglandin reductase 1 (PGR1), and ubiquitin carboxyl-terminal hydrolase (UCH). In this study, RNA interference (RNAi) was employed to validate the relevance of these five genes in responding the stimulation of CpG ODNs. Briefly, shrimps were fed CpG ODNs and subsequently injected dsRNA targeting these five genes for interference. Finally, the non-specific immune parameters of shrimps, including the expression of immune-related genes and antioxidant capacity of hepatopancreas, as well as the mortality of shrimps after pathogen attack were assessed. The tissue distribution analysis revealed a high abundance of CYP in the hepatopancreas, γ-BDO in the hemocytes, ApD in the eyestalk, PGR1 in the hemocytes, and UCH in the gonad. After blocking CYP, ApD, and UCH through RNAi, a significant down-regulation of the mRNA expression levels of immune-related genes, including ALF, TNF-α, Toll, and TOR, was observed. Additionally, a notable decline in the activity of antioxidant enzymes, such as CAT, GPX, GST, and SOD, was also observed. Moreover, the mortality rates of shrimps in the CYP, ApD, and UCH inhibited groups significantly increased compared to other treatment groups following exposure to Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VpAHPND) and white spot syndrome virus (WSSV). These results collectively suggest a close association of CYP, ApD, and UCH with the function of CpG ODNs in shrimps which will provide significant theoretical insights into comprehending the mechanism of CpG ODNs and optimizing their practical application in shrimp's aquaculture.

Biofloc System with Different Carbon Sources Improved Growth, Haematology, Nonspecific Immunity, and Resistivity against the Aeromonas hydrophila in Common Carp, Cyprinus carpio

Biofloc technology (BFT) is one of the most sustainable aquaculture system, which is based on the principle of nutrient recycling and addition of carbon to enable heterotrophic microorganisms to the system. To evaluate the performance of the biofloc culture system for Cyprinus carpio fingerlings, a 60-day growth trial was conducted. The fingerlings (n = 600) of average body weight (4.92 g ± 0.14) were stocked in 12 circular fiberglass tanks (300 L, volume 10.59 cft) to form three biofloc treatments (T1, T2, and T3) along with one control group. The carbon sources for treatments were sugarcane molasses, tapioca, and wheat. The C/N ratio of 15 was maintained for all treatments. After 60 days of rearing, the fish were challenged with Aeromonas hydrophila, and the relative percentage survival (RPS) was observed over 14 days. A haematological, nonspecific immune, and stress parameters were analyzed using blood and serum samples collected at intervals of 20, 40, and 60 days. According to the results, the carbon sources affected the water quality parameters but were still adequate for fish welfare. An increased biofloc volume was observed with tapioca. Growth performance and better feed conversion ratio were recorded in biofloc with the tapioca group. The hematological parameters, including haemoglobin (Hb), hematocrit (HCT), white blood cells and lymphocytes were significantly (P &lt;0.05) higher in biofloc-based tapioca group than in other treatments and control. Further, the serum protein, globulin, albumin, total immunoglobulin, and respiratory burst activity were also found significantly (P &lt;0.05) higher in biofloc with tapioca as carbon source. However, the lysozyme activity was higher in biofloc with the wheat group. The RPS in tapioca was significantly higher, followed by biofloc with wheat. In conclusion, the tapioca-based biofloc can improve C. carpio growth, haematology, and nonspecific immune response under zero water exchange.

Effects of Dietary Star Apple (Chrysophyllum cainito L.) Peel Extract on Growth Performance, Intestinal Histology, Hematology, and Non-Specific Immune Parameters in Common Lowland Frog (Rana rugulosa Wiegmann)

Star apple (Chrysophyllum cainito L.) has been used to treat several diseases. However, using this plant as a feed additive in aquaculture production is rare. Therefore, this work aimed to investigate the effects of dietary star apple peel extract (SAPE) on growth performance, intestinal histology, hematology, and non-specific immune parameters in common lowland frog (Rana rugulosa Wiegmann). Peel samples from star apple fruits were collected, dried, and extracted with methanol. Alkaloids, flavonoids, phenolics, saponins, tannins, and steroids were detected in SAPE at varied concentrations. Frogs of average weight 8.50 ± 0.10 g were fed diets incorporating 0, 10, 15, and 20 g SAPE/kg diet. After six weeks of feeding, the frogs' growth and physiological parameters were evaluated. The results revealed that the growth and intestinal histology features of frogs fed SAPE diets were significantly increased compared with the control (P &lt;0.05). No significant differences among the treatments were observed in the survival rate, red blood cells, hematocrit, and hemoglobin (P &gt;0.05). Serum albumin was significantly enhanced in frogs fed a 10 g SAPE/kg diet (P &lt;0.05). Dietary SAPE significantly decreased serum alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, triglyceride, and cholesterol compared with the control (P &lt;0.05). Furthermore, frogs fed SAPE diets had significantly elevated lysozyme activity, leukocyte respiratory burst activity, complement activity, and immunoglobulin M compared with the control (P &lt;0.05). In conclusion, these results showed the beneficial effects of SAPE on the growth and health status of frogs with the appropriate level of 17.75 to 20.00 g/kg diet. Keywords: Medicinal plants, Common lowland frog, Growth performance, Immunity, Hematology

НЕКОТОРЫЕ ПОКАЗАТЕЛИ НЕСПЕЦИФИЧЕСКОГО ИММУНИТЕТА ЛЕЩА САРАТОВСКОГО ВОДОХРАНИЛИЩА

The study of some parameters of nonspecific humoral and cellular immunity in sexually mature bream of the Saratov Reservoir was carried out. The fish were caught by bottom trawl in September 2019 during a complex hydrobiological expedition aboard the R/V “Akademik Topchiev” organized by the Papanin Institute for Biology of Inland Waters, Russian Academy of Sciences. Trawling operations were performedt at three standard stations: 1 – Shiroky Buerak, 2 – Khvalynsk, 3 – Kashpir Rudnik. The first two stations were located in the lower reaches of the reservoir and the third one was in the central part. Fish blood was sampled from the tail vein to obtain serum and prepare smears for phagocytic activity of neutrophils. After autopsy, pieces of immunocompetent organs (kidney, spleen and liver) were also taken from the fish in dry sterile tubes. The level of antimicrobial properties and C-reactive protein of blood serum, nonspecific immune complexes in kidney, spleen and liver tissues were studied, the proportion of immunodeficient individuals and phagocytic activity of neutrophils were determined. The study established quantitative indicators of humoral and cellular immunity of bream of the Saratov Reservoir. The comparative analysis showed significant differences in antimicrobial properties of blood serum and the content of non-enzymatic cationic protein in lysosomes of neutrophils of peripheral blood in bream from the central part and the lower reaches of the reservoir. Fish caught in the central part of the reservoir were characterized by high level of bactericidal activity of blood serum and low level of phagocytic activity of neutrophils. The majority of the studied individuals had a positive level of C-reactive protein and unreliable differences in the content of IR in tissues and organs. The revealed differences are probably caused by the impact of different environmental factors on the bream organism.

ВЛИЯНИЕ ЭЛЛАГОТАНИНОВ И ПРОБИОТИЧЕСКОГО ПРЕПАРАТА “ЭКОФЛОР” НА ПОКАЗАТЕЛИ НЕСПЕЦИФИЧЕСКОГО ИММУНИТЕТА СТЕРЛЯДИ

The experimental study of the effect of feed additive based on ellagotanins and immobilized probiotic “Ecoflor” on some parameters of non-specific immunity of sterlet Acipenser ruthenus was carried out. Feed additives based on ellagotannins are one of the numerous preparations of natural origin. They have antibacterial and immunostimulating properties. Biologically active additive “Ecoflor” is a consortium of live antagonistically active strains of bifido- and lactobacilli immobilized on enterosorbent. During the experiment, control and experimental groups were kept in flow-through plastic pools. Sterlets were fed 6 times a day. Drugs were added to the feed according to the instructions. Sampling was carried out before the start of the experiment, on 7, 14, 30, 45 and 60 days. Material for the study was taken from 5 individuals from each group. Peripheral blood was taken from the tail vein. After autopsy, tissue pieces of immunocompetent organs (kidney, spleen and liver) were taken from the fish into dry sterile tubes. Blood coagulation and clot retraction were waited for to obtain serum. The serum was then withdrawn with a syringe with a fine needle and transferred into an Eppendorf tube. For further studies, the homogenate was prepared from kidney, spleen and liver with physiological solution in the ratio of 1:6. The level of bacteriostatic activity, C-reactive protein and nonspecific immune complexes was determined in blood serum samples. In homogenates of kidney, spleen and liver the content of immune complexes was determined. The study established high indices of antimicrobial properties of blood serum in all studied fish and the absence of immunodeficient individuals. Lower indices of bacteriostatic activity in experimental groups and zero percent of immunodeficient individuals indicate insignificant influence of preparations on nonspecific antibacterial defense. The majority of the studied fish had a positive level of C-reactive protein, which indicates the presence of inflammatory processes in the body. The content of nonspecific immune complexes in the liver was several times higher than in other tissues, which may be due to the neutralization of components included in the preparations.

PEMBERIAN EKSTRAK DAUN KETAPANG UNTUK MENINGKATKAN IMUN – NON SPESIFIK PADA IKAN (ARTIKEL REVIEW)

This review article focuses on the administration of ketapang leaf extract to enhance non-specific immunity in fish. Ketapang leaves have been of interest as a potential immunostimulant in aquaculture to boost the non-specific immune response in fish. In this review, various studies exploring the effects of ketapang leaf extract on the non-specific immune response of fish have been examined. The findings suggest that the administration of ketapang leaf extract can lead to an increase in non-specific immune parameters, such as phagocytosis activity, lysozyme activity, and total protein content. The potential use of ketapang leaf extract as an immunostimulant in aquaculture shows promising results in enhancing the non-specific immune response of fish. Strengthening the non-specific immune system can help fish combat various pathogens and diseases, thereby improving their overall health and survival in aquaculture settings. However, further research is needed to fully understand the mechanisms of action and optimal dosage of ketapang leaf extract as an immunostimulant. Additionally, considering its potential positive impact on fish health, the use of ketapang leaf extract in aquaculture warrants comprehensive studies to ensure its safe and effective implementation.

Effect of killed autogenous polyvalent vaccines against Vibrio harveyi, V. alginolyticus and Streptococcus iniae on survival and immunogenicity of Asian seabass (Latescalcarifer)

Vibriosis and Streptococcosis are the most important bacterial diseases that infect Asian seabass (Lates calcarifer) in various stages of its life cycle. Vaccination is a cost-effective strategy to prevent the occurrence of infectious diseases and increase sustainability in the aquaculture industry. This study was aimed to develop and evaluate a killed polyvalent vaccine against Vibrio harveyi, V. alginolyticus and Streptococcus iniae, delivered by intraperitoneal injection in Asian seabass. The fish were divided into three groups with 60 fish in triplicate: I) a control group injected with phosphate-buffered saline (PBS), II) a group vaccinated by polyvalent vaccine (V. alginolyticus + V. harveyi + S. iniae) and III) a group vaccinated with the same polyvalent vaccine plus an oral booster. Immunological parameters and antibody titer were measured before and at three, five-, and eight-weeks post-vaccination. The efficacy of the killed vaccine was assessed five weeks post-vaccination by challenging with each isolate separately. The vaccinated groups had higher survival rate than control group. The highest relative percentage survival rate, 85.71 ± 3.57 % was observed in group III when challenged with V. harveyi. The vaccinated fish produced significantly higher antibody titers against V. alginolyticus, V. harveyi and S. iniae than the control group (P < 0.05). Non-specific immune parameters were significantly enhanced in the vaccinated groups, especially group III, compared to the control. The results demonstrated that the administration of a killed polyvalent vaccine can effectively protect Asian seabass against V. alginolyticus, V. harveyi and S. iniae.

Dietary supplementation of Terminalia arjuna bark extract improved growth, biochemical parameters and innate immunity in Heteropneustes fossilis larvae

Achieving healthy aquatic environment has been elusive with the process of intensification due to irrational use of chemicals. Plant extracts are hence candidate of choice as an alternative in aquaculture. Moreover, the poor larval survival of Heteropneustes fossilis (singhi) needs urgent research attention, which can be effectively addressed by boosting immunity, particularly by enhancing nonspecific immunity in the larvae. Hence, the study investigates the effects of dietary supplementation of Terminalia arjuna (TA) methanolic bark extract on growth, immune biomarkers and biochemical status in the stinging catfish, Heteropneustes fossilis larvae. 180 numbers of fish larvae (15 days post hatch; 22 ± 2.6 mm mean length and 43 ± 3.5 mg mean weight) were equally distributed in to four groups and fed with 0 % (control), 0.1 %, 0.25 % and 0.5 % of TA supplemented feed. Growth attributes, non-specific immune and biochemical parameters were analysed after 40 days of feeding. Results demonstrated that, larval group fed with 0.25 % TA extract had significantly (P < 0.05) improved final body weight, weight gain percent, daily weight gain and SGR compared to other treatment groups. Supplementation with 0.25 % TA extract significantly (P < 0.05) elevated respiratory burst activity (RBA), myeloperoxidase activity (MPO), lysozyme and biochemical parameters including alkaline phosphatase (ALP) activity, total protein, albumin as well as SOD level. However, 0.5 % TA dietary group revealed reduced growth and compromised immunity in the larva. Moreover, 0.25 % level significantly (P < 0.05) reduced hepato-cellular enzymes like ALT and AST activities and glucose as compared to control. However, the increase in extract level up to 0.5 % in the diet exhibited stress, which is evident from undermined growth and immunity. The present study suggests that the dietary TA bark extract inclusion level up to 0.25 % is safe limit and can modulate immunity, antioxidant and growth performance in stinging catfish, H. fossilis larvae.

Aquatic product hydrolysates increase rearing performance in red seabream (Pagrus major), fed a low fish meal diet, in both controlled and stressed conditions: From growth to stress responses

Although aquaculture industry has made great efforts to reduce the levels of fish meal (FM) in aquaculture feeds, further efforts and investigations are still needed to increase aquaculture production, which has more than tripled in the last two decades. This study was implemented to Six replicate groups of fish (24.6 ± 0.1 g) were fed one of the experimental diets to apparent satiety twice daily for 15 weeks; half of them were subjected to a daily net chasing stress for 1 min in the morning, 1 h before feeding. At the end of the feeding trial, fish were challenged with Edwarselia tarda injection. LFM diet resulted in comparable growth and feed efficiency performance to HFM group. However, significant impairments were observed in apparent digestibility coefficients, condition factor, hematocrit and serum super oxide dismutase activity. Fish fed LFM showed much lower resistance to E. tarda challenge. Both TH and SH resulted in enhanced fish nutritional and health performance with significant improvements in growth performance, feed efficiencies, digestibility, serum non-specific immunity and gut morphometric parameters. Fish fed TH and SH also exhibited the highest survival after E. tarda challenge. Principal component analysis (PCA) showed significant differences between stress and dietary groups for dimension 1 (33.3% of the variability), which was mostly characterized by growth and health variables. SH and TH coordinates were significantly higher on dimension 1 compared to HFM and LFM ones. Daily repeated stress affected most of measured performance parameters of all dietary groups with very few interactions. The stressed fish groups fed TH or SH showed lower cortisol levels compared to those fed HFM and LFM (p < 0.01). Strong correlations were observed between feed efficiency and fish gut morphometrics as quantified by villi length, enterocyte height and goblet cell density. Dietary supplementation of aquatic protein hydrolysates such as TH and SH appeared to be essential for maintaining good fish performance when they were subjected to a daily husbandry stressor or to an infectious challenge.

Effects of Sargassum horneri as a substitute for Undaria pinnatifida in high plant protein diet for juvenile Pacific abalone (Haliotis discus discus, Reeve 1846)

Sargassum horneri is an abundant seaweed causing golden tides on the southwestern coast of South Korea. Undaria pinnatifida is an edible and expensive seaweed conventionally used in abalone diets. The study was conducted to evaluate Sargassum horneri as a substitute for U. pinnatifida in high plant protein diets for juvenile Pacific abalone (Haliotis discus). Dried and ground U. pinnatifida and S. horneri were used for the experiment. Diets were formulated to contain 100 g kg-1 fish meal and 300 g kg-1 seaweed meal. Control diet (SA0) was prepared including 300 g kg-1U. pinnatifida meal. Three other diets were designed to contain 100, 200, and 300 g kg-1S. horneri (SA10, SA20, and SA30) by replacing U. pinnatifida meal from control. Triplicate groups of abalones stored in fifteen plastic baskets were hand-fed one of four experimental diets or dried U. pinnatifida once every other day for 16 weeks. Growth performance of abalone fed SA10 and SA20 diets were comparable to SA0 and U. pinnatifida groups. Hemolymph non-specific immune parameters were significantly higher in SA20 group compared to SA0 and U. pinnatifida groups (p ˂ 0.05). Moisture and lipid levels in edible portions of abalone fed S. horneri diets were significantly higher than in control (p ˂ 0.05). Water stability was higher in SA0 diet and gradually decreased with the increase of S. horneri meal in diets. After air exposure, abalone fed S. horneri diets exhibited higher survival than SA0 and U. pinnatifida groups. Therefore, S. horneri can be used to replace U. pinnatifida from abalone diets. The proper combination of U. pinnatifida and S. horneri meal in abalone diet containing a low level of FM appears to be approximately 100 and 200 g kg-1.

Protective Effects of Chlorella vulgaris Supplemented Diet on Antibacterial Activity and Immune Responses in Rohu Fingerlings, Labeo rohita (Hamilton), Subjected to Aeromonas hydrophila Infection.

The current study focuses on the antibacterial activity and potential efficiency of dietary supplements of Chlorella vulgaris on the immune response, improved growth performance, and disease resistance of Labeo rohita fingerlings against Aeromonas hydrophila infection. Crude ethanolic extract of Chlorella and partially purified fractions of the extract were tested against two selected fish pathogens using the disc diffusion method. A total number of 360 rohu fingerlings (25 ± 2 g) were allocated to 4 treatments for 90 days. They were fed with an experimental diet containing Chlorella powder (0, 0.1, 0.5, and 1.0 g Kg-1 of a basic diet). To evaluate the non-specific immunity parameters including serum bactericidal, lysozyme activity, superoxide anion production, and biochemical and haematological indices, the fish were sampled at day 30, 60, 90, and after bacterial challenge. Mortalities of the fish were observed over 10 days post challenge with A. hydrophila. The protein and globulin levels of the treatment group were significantly higher after being treated with Chlorella than those of the control group. The total blood-cell count and haemoglobin content were also increased in the algal-diet-treated group. Among all the experimental diets, the 0.5 g Kg-1Chlorella fed group of fish showed significantly (p < 0.05) increased serum bactericidal activity and superoxide anion production when compared with the control group on day 90. Maximum lysozyme activity (750.00 ± 3.27) was noticed in the 1.0 g Kg-1 diet fed group on day 30. The Chlorella treated group exhibited a better growth performance of the fish. The maximum survivability (86.5%) was recorded in the 1.0 g Kg-1 diet fed group at the end of the 10-day fish exposure to A. hydrophila. These results suggest that the optimum dietary Chlorella supplementation could be 0.5-1.0 g Kg-1 of the diet, which stimulates immunity and protects L. rohita from A. hydrophila infection.

Characteristics and biological control functions of Bacillus sp. PM8313 as a host-associated probiotic in red sea bream (Pagrus major) aquaculture.

Host-associated probiotics (HAPs) are bacteria originally isolated from rearing water or the host's gastrointestinal tract in order to enhance the host's growth and health. This study investigated the HAP potential of Bacillus sp. PM8313, isolated from wild red sea bream (Pagrus major), through characterization and feeding trials. Results based on invitro tests showed that PM8313 is safe, confirming its hemolytic, cytotoxic, and antibiotic resistance. In addition, PM8313 showed advantages as a probiotic with high viability in the gastrointestinal model and a high cell adhesion rate. Whole-genome sequencing demonstrated that PM8313 has a 4,615,871 bp single circular chromosome and a guanine-cytosine content of 45.25%. It also showed the absence of genes encoding virulence factors, such as cytotoxin, enterotoxin, hemolysin, sphingomyelinase, and phospholipase. In the feeding trial, a supplemental diet of 1×108CFU/g PM8313 positively altered the weight gain, digestive enzyme activity, and intestinal microbiota composition of red sea bream. Analysis of nonspecific immune parameters and immune-related gene expression, and a challenge test showed that PM8313 supplementation increases immunity and pathogenic bacteria resistance. Our findings suggest that PM8313 should be considered for application as a novel HAP to red sea bream aquaculture.