Nervous necrosis virus induced oxidative stress and associated antioxidative response in the brain of Asian seabass were evaluated in the present study. The infection resulted in an increasing level ...of nitric oxide production induced by the expression of inducible nitric oxide synthase. The activity of NRF2 was increased and up-regulated the expression of ARE stimulatory genes including heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase-1 (NQO-1), superoxide dismutase (SOD) and catalase (CAT). The antioxidant enzyme SOD and CAT activity were diminished following infection even though the gene expression was upregulated. The activity of glutathione metabolism markers GPx, GR and GST were affected by the NNV infection. Expression of ERK-1 was up-regulated whereas AMPK down-regulated. Our results suggest that NNV influence the homeostasis of the cell by oxidative stress and affects the antioxidative responses by perturbing the glutathione metabolism and antioxidant enzyme activity.
•NNV induced oxidative stress and associated antioxidative responses in the brain of Asian seabass was evaluated•Infection resulted in increasing level of nitric oxide production by the expression of inducible nitric oxide synthase.•The activity of NRF2 was increased and up-reguated the expression of ARE stimulatory genes including heme oxygenase-1 (HO-1), NAD(P)H quinone oxidoreductase-1 (NQO-1), SOD and CAT.•The antioxidant enzyme SOD and CAT activity diminished following infection even though the gene expression was up-regulated.•The activity of glutathione metabolism markers GPx, GR and GST was affected by the NNV infection.•ERK-1 expression was up-regulated whereas AMPK down-regulated.•NNV influence the cells homeostasis by oxidative stress and affects the antioxidative responses
Toxicological studies on the emergent pollutant, triclosan (TCS) have established the wide-ranging effects of the compound on fish and other aquatic organisms. Although the available literature ...describes the standalone effects of TCS on growth and metabolism of fish yet, reports about the combined effects of TCS with microbial pathogens are scarce. In a real environment, a combined exposure to TCS and pathogens is of common occurrence, therefore, such investigation facilitates in developing a better understanding about the gross effects of pollutants and microbial pathogens on aquatic organisms including fish. In this context, the experimental fish (striped catfish, Pangasianodon hypophthalmus) were exposed to three different concentrations of TCS viz. 10, 20 and 30% of 96 h LC50 (1177 μg L−1) for 45 days including two control group firstly solvent control (without TCS) group and another one (without solvent and TCS) group in triplicate. Sampling was performed fortnightly and blood, serum and tissues (liver, and gills) samples were collected for evaluating immunological and biochemical parameters. Following 45 days of the experiments, the experimental fish in each treatment group including controls were challenged with a fish pathogenic bacterium Edwardsiella tarda (LD50 dose) and fish mortality was daily monitored for calculating cumulative mortality till 7 days and further, relative per cent survivable was estimated. A significant reduction in cellular immune responses i.e. respiratory burst activity (RBA), myeloperoxidase activity (MPO), phagocytic activity (PA) and humoral immune components viz. serum lysozyme activity, total immunoglobulin in serum, ceruloplasmin level, serum total protein, albumin and globulin level was evident in TCS exposed groups in comparison to control during the experimental periods. Further, oxidative stress parameters viz. superoxide dismutase (SOD), catalase (CAT), glutathione-s-transferase (GST) activity in liver and gill tissue exhibited a dose-dependent increase in activity with related to TCS concentration during the experimental periods. A significant reduction in relative percentage survival was observed with increasing TCS concentration. The present study reveals that TCS can inhibit the cellular and humoral components of the innate immune system of the fish and can elevate the mortality due to TCS mediated immunosuppression in fish during the bacterial infection.
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•TCS suppresses the cellular mediated immune response with decrease in RBA, MPO and lysozyme activity in fish.•Total protein, albumin and globulin level were reduced in serum of TCS exposed fish.•TCS exposed fish showed significant reduction in total immunoglobulin.•TCS exposed fish showed an elevated mortality during E. tarda infection.
Trained immunity refers to the memory acquired by innate immune cells, leading to cross-protection and non-specific responses to subsequent infection, thereby improving host survival. Trained ...immunity induction is a combined effect of immune signaling, metabolic changes, and epigenetic modifications. The present study evaluated the induction of markers of the phenomenon of trained immunity in common carp, which is trained using β-glucan. The mammalian target of rapamycin (mtor) and hypoxia-inducible factor (hif1α), the metabolic basis of trained immunity; the histone deacetylase (hdac7), one of the markers of epigenetic modifications, metabolic activity of activated cells and expression profiles of proinflammatory cytokines viz. il6a, tnfαa2, and ifnγ were targeted in the study and analyzed in vivo. Besides in vivo analysis, in vitro analysis of mtorc2, hif1α, hdac7, and ifnγ were analyzed. In vitro analyses were performed on head kidney macrophages isolated and maintained in L-15 media and double trained with β-glucan at 100μg/mL. The culture supernatant was collected at different time intervals and processed for expression studies. Healthy common carp were injected with β-glucan at 20 mg/kg body weight for training followed by a resting phase for 6 days and were restimulated with the same dose. Head kidney was collected from the fish post-induction as well as post-restimulation. The expression profile of mtorc2, hdac7, and hif1α were found elevated post-stimulation of β-glucan. Further, a significantly upregulated expression profile of proinflammatory cytokines (ifnγ, il6a and tnfαa2) was observed. Increased glycolysis in the cells post-β-glucan stimulation was confirmed by the high lactate and LDH production detected in the cell culture supernatant. Overall, the study revealed the expression profile of the trained immunity markers and the increased metabolic activity in cells induced with β-glucan, which further validates that the action of trained immunity is indispensable in fish on encounter with a potential ligand. The study supports the existing reports on trained immunity in teleost fish with evidence at the genomic level. However, further studies are required to understand the responses and actions of trained immune cells during infection in detail.
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•Expression profiles of trained immunity markers in common carp post immune training with β-glucan.•Elevated expression profiles of trained immunity markers and proinflammatory cytokines were observed post-training.•Increase in metabolic activity and production of metabolites revalidates the phenomenon of the metabolic shift in trained immune cells.
Polymeric immunoglobulin receptor (pIgR) is a protein that transports Immunoglobulins (Igs) from epithelial cells into the external secretion system of the animal. In the present study, we ...characterized the partial pIgR gene from Labeo rohita and analyzed its expression in response to the pDNA (pGPD-IFN) vaccine, and studied its correlation with the expression of IgM, in the mucosal-associated lymphoid tissues (MALT). The significant (p < 0.05) up-regulation of pIgR mRNA was observed in the mucosal tissues of vaccinated fish by qRT-PCR. The highest expression of the gene was detected in gill tissue at 15 days post-vaccination (dpv) followed by skin and gut at 30 dpv. The expression of IgM also showed a similar pattern and indicated a direct correlation of pIgR expression in all the tested tissues. The protective immune response of the DNA vaccine was measured as the relative percentage of survival (RPS) by challenging vaccinated fish with live Edwardsiella tarda (1 × 105 CFU/Fish). The result showed a significantly high relative percentage survival (RPS) in the vaccinated group (47.05%) compared to the control group. Many factors contributing to the immune response of the vaccine. One of the most critical aspects is the rise in IgM level in local tissues. In other higher vertebrates, pIgR is reported to act as the transporter of IgM. The positive correlation in the expression of pIgR and IgM observed in the present study demonstrated the possible role of pIgR as the transporter of IgM in L. rohita. The study suggests the possibility of the secretory nature of IgM in fish.
•Characterization of polymeric immunoglobulin receptor gene (pIgR) in L. rohita•mRNA expression of pIgR and IgM gene in mucosal associated lymphoid tissues in response to DNA vaccine and E. tarda infection•Vaccine efficacy study against E. tarda infection in terms of relative percentage survival (RPS).
The inflammasome is a multimeric protein complex that plays a vital role in the defence against pathogens and is therefore considered an essential component of the innate immune system. In this ...study, the expression patterns of inflammasome genes (
NLRC3
,
ASC
, and
CAS-1
), antiviral genes (
IFNγ
and
MX
), and immune genes (
IL-1β
and
IL-18
) were analysed in
Oreochromis niloticus
liver (ONIL) cells following stimulation with the bacterial ligands peptidoglycan (PGN) and lipopolysaccharide (LPS) and infection with TiLV. The cells were stimulated with PGN and LPS at concentrations of 10, 25, and 50 µg/ml. For viral infection, 10
6
TCID
50
of TiLV per ml was used. After LPS stimulation, all seven genes were found to be expressed at specific time points at each of the three doses tested. However, at even higher doses of LPS,
NLRC3
levels decreased. Following TiLV infection, all of the genes showed significant upregulation, especially at early time points. However, the gene expression pattern was found to be unique in PGN-treated cells. For instance,
NLRC3
and
ASC
did not show any response to PGN stimulation, and the expression of
IFNγ
was downregulated at 25 and 50 µg of PGN per ml.
CAS-1
and
IL-18
expression was downregulated at 25 µg of PGN per ml. At a higher dose (50 µg/ml), IL-1β showed downregulation. Overall, our results indicate that these genes are involved in the immune response to viral and bacterial infection and that the degree of response is ligand- and dose-dependent.
DNA vaccine is an important tool to elicit both humoral and cellular immunity. Present study investigates mucosal immune response of Labeo rohita (15 ± 04 g) to plasmid DNA (pDNA) vaccine ...macromolecule complexed with nanoparticles (NPs). Poly lactic-co-glycolic acid (PLGA), Chitosan (Chit) and PLGA-Chit-NPs were synthesized by double emulsion solvent evaporation method. Synthesized NPs were complexed with pDNA (pGPD + IFN) vaccine construct. Size and zeta potential of PLGA-NPs, Chit-NPs and PLGA-Chit-NPs-pDNA complex were recorded to be 120 nm and +0.5 mV, 117 nm and +32 mV, 189 nm and +11 mV, respectively. Immunization by immersion was carried out in two groups receiving PLGA-Chit-NPs-pDNA (T1) and PLGA-NPs-pDNA (T2) respectively. After immersion, samples were collected on 0, 2, 4, 7, 15 and 30 days from mucosa-associated lymphoid tissues (MALT) for mRNA expression studies of IgM, IgD and IgZ using qRT-PCR. Significant up-regulation of the mRNA expression of IgM, IgD, and IgT were observed in MALT in immunized fish compared to control. After 30 days post-immunization fish were infected with a virulent strain of Edwardsiella tarda. The highest relative percentage survival was observed in T1 (64.7%) compared to T2. The study showed better efficiency of pDNA-PLGA-Chit-NPs compared to pDNA-PLGA-NPs for inducing adaptive mucosal immunity in fish.
Intensification and diversification of the aquaculture practices made an opening to the emergence of new viral diseases daunting the farmers to achieve a sustained production. Viruses are obligatory ...parasites abundant in the aquatic environments and are being introduced in the sector directly or indirectly. Infectious Myonecrosis Virus (IMNV) is an emerging shrimp RNA virus causing the disease, infectious myonecrosis (IMN). The disease was reported first from Brazil and currently the geographical locations of infection span in Brazil and Indonesia. Research are centered on the viral pathogenesis, viral entry, disease prevention and epidemiology, diagnostics and molecular pathology. The recent developments in the synthetic and molecular biology techniques have paved way to explore IMNV at its molecular levels, yet further research has to be conducted to fully understand the virus as well as diagnostics of the disease with cause. This review covers all the aspects of the virus, IMNV and the disease IMN, research developments and emphasizes on the current progress and the future prospects of the research in control and prevention strategies.
•Infectious myonecrosis virus (IMNV) is an emerging penaeid shrimp virus belongs to the family Totiviridae•The virus is endemic to Brazil and Indonesia with a potential chance to spread transboundary.•OIE is listed IMNV as one of major viral pathogen to crustaceans and initiated the active surveillance•The infection is characterized by whitish muscles along the abdomen and tail region•Good Management Practices can prevent the virus and diagnostics are under research phase
Member of the dynamin family of large GTPases, dynamin-related protein 1 (Drp1) dependent mitochondrial fission is an intricate process regulating both cellular and organ dynamics. Present study ...shows that NNV perturbs mitochondrial dynamics by promoting Drp-1 dependent mitochondrial fission, which attenuates MAVS mediated downstream signaling. NNV infected SISS cells revealed induction in Drp1 expression and subsequent translocation into mitochondria. The level of MAVS expression was up-regulated over a period of 24 hpi and declined with the progression of NNV infection at 48 and 72 hpi confirmed by western blot and mRNA transcript analysis. Drp-1 displayed its association with fragmented mitochondria and the transcript abundance was significant post infection along with Mff. Expression levels of IRF-3 IFN-1 and Mx followed a similar pattern with abundant expression at 48 hpi and diminished expression during the further period. Importantly, silencing of Drp1 caused significant elevation in the RLR downstream molecules and reduction in viral RNA expression. These results suggest that NNV-induced mitochondrial fission serve to attenuate host RLR signaling. This provides an illustration of host–pathogen interaction in which the virus evades innate immunity by enhancing mitochondrial fission and perturbs MAVS, and the downstream molecules.
•NNV infection induced mitochondria RoS production and displayed mitochondrial fragmentation.•Upon infection the Drp 1 gets phosporylated and translocated to mitochondria.•Protein and mRNA transcript abundance of MAVS and downstram molecules decreased significantly after NNV infection.•Silencing of Drp1 re-established the RLR signaling cascade invitro.
Immunoglobulin (IgM) is the primary immunoglobulin essential for defense mechanisms in fish. It is difficult to reliably quantify IgM because a lack of standardization in methodology and limited ...availability of commercially reagents. In the present study, a polyclonal antibody was developed for the specific detection and quantification of IgM in Labeo rohita. Recombinant bicistronic NanoDNA plasmid (RBND Vac) encoding the glyceraldehyde-3-phosphate dehydrogenase gene of Edwarsiella tarda conjugated with poly (lactic-co-glycolic acid) - Chitosan (PLGA-Chit) was developed and its potential as a DNA vaccine, to prevent the infection of E. tarda in L. rohita was investigated. Two treatment groups T1 - (PLGA-Chit-NPs-pDNA), T2 - (PLGA-NPs-pDNA) and one control group (T0 - 1 × PBS) were utilized. Polyclonal antibody was developed to estimate IgM titers in the serum and mucosal associated tissues (MAT) using Enzyme-linked Immunosorbent Assay (ELISA) technique. Additionally, immune gene expression was studied using qRT-PCR. Vaccinated groups also exhibited a significant increase in the total serum protein, globulin concentration and relatively less mortality was observed in T1 group. IgM level in serum and mucosal tissues (skin, gill and gut) increased significantly days post vaccination compared to control group, also non-specific immune parameters (myeloperoxidase and lysozyme levels) showed significant improvement in vaccinated fish. Furthermore, histopathological examination confirmed minor damage in physiological structure of kidney and liver tissues in vaccinated fish. Knowledge of the immunoglobulin in L. rohita primed with RBND Vac complex provides the better protection against E. tarda. The normal physiology findings of this study will aid in monitoring changes in the health status of fish, when the animals undergo vaccination by immersion method.
•Species-Specific IgM Antibodies were generated using IgM of Labeo rohita.•Musosal immunity enhancement using RBND Vac.•Post vaccination by immersion method fish were challenged with virulent strain of Edwasiella tarda.•Relatively highest percentage survival was recorded in PLGA-Chit-NPs-pDNA group.
Peptidoglycan recognition proteins (PGRPs) function in host antibacterial responses by recognizing bacterial peptidoglycan (PGN). In the present study, a short pgrp5 (named mpgrp5) was identified in ...Cirrhinus mrigala (mrigal). The full-length cDNA of the mpgrp5 gene was 1255 bp, containing an open reading frame of 746 bp encoding a protein of 248 amino acids. The predicted protein contained the typical Pgrp/amidase domain, conserved Zn
, and PGN binding residues. The phylogenetic analysis revealed that the mpgrp5 is closely related to Pgrps reported in Labeo rohita, Cyrinus carpio, and Ctenopharyngodon idella. The ontogenetic expression of mpgrp5 was highest at 7 days post-hatching (dph) and its possible maternal transfer. mpgrp5 was constitutively expressed in all tissues examined, with the highest expression observed in the intestine. Furthermore, mpgrp5 was found upregulated in mrigal post-challenge in a time-dependent manner at 6hpi in the liver (3.16 folds, p < 0.05) and kidney (2.79 folds, p < 0.05) and at 12hpi in gill (1.90 folds, p < 0.01), skin (1.93 folds, p < 0.01), and intestine, (2.71 folds, p < 0.05) whereas at 24hpi in spleen (4.0 folds, p < 0.01). Our results suggest that mpgrp5 may play an important role in antibacterial immune response from early life stages in mrigal.
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