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.
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.
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
•This study investigated the effects of dietary lipopolysaccharide (LPS) on immune response, immune gene expression of Labeo bata.•Dietary LPS enhances the immunity and disease resistance in L. ...bata.•The optimum requirement for LPS in feed of L. bata was estimated to be 100mgkg−1.•Short term feeding of LPS may help L. bata to overcome periods of increased disease risk.
This study investigates the effects of dietary lipopolysaccharide (LPS) as an immunostimulant on hematology, innate immunity, immune gene expression and protection against Edwardsiella tarda on Labeo bata. A basal diet supplemented with 0, 50, 100 and 150mg LPS kg−1diet was fed to the four different groups for 30days. The haematological (total erythrocyte count, total leukocyte count, total serum protein, albumin and globulin), innate immune parameters (respiratory burst, serum lysozyme, myeloperoxidase and serum bactericidal activity), immune gene expression (C3, β-2 microglobulin, lysozyme g, transferrin, IFN-1, IFN-γ) were monitored at 7th, 15th, 30th day and one day post challenge (DPC) with E. tarda. All the studied haematological, innate immune parameters and expression of immune gene increased significantly (p≤0.05) in LPS fed group in comparison with control. However the group fed 100mgkg−1 LPS in feed showed highest activity on 7th day and 1DPC. The group fed 100mgkg−1 LPS also recorded highest relative percent survivability after challenge with E. tarda. Therefore this study suggests that LPS at 100mgkg−1 could be used as an immunostimulant in feed to enhance the protection of bata during periods of increased disease risk.
Galectin-9 is a b-galactoside-binding tandem repeat galectin that regulates many cellular functions, ranging from cell adhesion to pathogen recognition. In spite of extensive study of mammalian ...galectin importance in immune system, little is known about that of fish. To study the normal expression and immune response of Labeo rohita to pathogens, a tandem-repeat galectin-9 from Labeo rohita was identified and named LrGal-9. Its full-length cDNA was 1534 bp encoded 291 amino acids (35.12 KDa), shared the highest 81% identity with the galectin-9 of Danio rerio. LrGal-9 identified in this study lacked signal peptide and a transmembrane domain like galectin-9 members reported in other fishes. Quantitative PCR showed that LrGal-9 was lowly expressed in gill, muscle, heart, highly expressed in tested immune tissues (intestine, kidney, liver, spleen) in normal body. After Aeromonas hydrophila challenge, LrGal-9 was remarkably increased in all tested immune tissues in a time-dependent manner. These results suggest that LrGal-9 plays a role in innate immunity in Labeo rohita.
•Expression and immune response of L. rohita to pathogens, a tandem-repeat gal9 was identified and named LrGal-9.•LrGal-9 was lowly expressed in gill, muscle, heart and highly expressed in intestine, kidney, liver and spleen.•LrGal-9 plays an important role in innate immunity in Labeo rohita.
The present study evaluated the effect of dietary andrographolide (EC 50%) on growth, non-specific immune parameters and disease resistance against Aeromonas hydrophila infection in Indian major ...carp, Labeo rohita fingerlings. Fishes were fed with formulated diet containing andrographolide as T0 (0.00%), T1 (0.05%), T2 (0.10%), T3 (0.20%), T4 (0.40%) and T5 (0.80%) for 42 days. Fishes were challenged with A. hydrophila 42 days post feeding and relative percentage survival (RPS) was recorded over 14 days post challenge. Blood and serum samples were collected for nonspecific immune parameters on 14, 28 and 42 days of feeding and growth performance was evaluated at the end of experiment. The results revealed that fishes fed with andrographolide showed significant (p < 0.05) increase in NBT levels, myeloperoxidase activity, phagocytic activity, serum lysozyme activity, and serum antiprotease activity when compared to the control group. The weight gain, specific growth rate, feed conversion ratio and protein efficiency ratio of fishes fed with andrographolide were found to be significantly (p < 0.05) differed compared with control. Dietary andrographolide at the level of 0.10% showed significantly (P < 0.05) higher RPS (74.06%) against A. hydrophila infection than control. The results revealed that andrographolide supplemented diet has a stimulatory effect on non-specific immune parameters along with improved growth performance and increased disease resistance against A. hydrophila infection in L. rohita fingerlings.
This study was performed to evaluate the effect of dietary chitosan on haematology, innate immunity and protection against Vibrio anguillarum in Asian seabass, Lates calcarifer. A basal diet ...supplemented with 0, 5, 10 and 20 g chitosan kg⁻¹ diet was fed to the four different groups for 60 days. The haematological (total erythrocyte count, total leucocyte count, total serum protein, albumin, globulin and albumin‐globulin ratio) and innate immune parameters (phagocytic ratio, respiratory burst, serum lysozyme and serum bactericidal activities) were monitored at fortnight interval to assess the effect of chitosan feeding in Asian seabass. All the studied haematological and innate immune parameters were increased significantly (P ≤ 0.05) in chitosan‐fed groups in comparison with control. However, the group fed diet containing 10 g chitosan Kg⁻¹ feed showed highest haematological and innate immune parameters on 45ᵗʰ day in comparison with other groups. Moreover, the fish fed the diet containing 10 g chitosan Kg⁻¹ feed had significantly higher post‐challenge survival (75.56 ± 4.44%) on the 30th day following V. anguillarum challenge. Therefore, this study suggests that chitosan at 10 g kg⁻¹ diet could be used as prophylactic in Asian seabass culture to enhance the protection against any possible infection by V. anguillarum.
Emerging and existing diseases are the major havoc to the shrimp aquaculture industry. Outbreaks of viral epidemics severely hinder the sustainable farming system with significant economic losses ...worldwide. The Pacific white shrimp, Penaeus vannamei farming was seriously affected by infectious myonecrosis caused by a double-stranded RNA virus, infectious myonecrosis virus (IMNV). Early and rapid diagnostics is the priority on considering the efficient management and prevention measures. So, the present study utilized the accurate, rapid and specific detection capabilities of real-time PCR on SYBR Green platform to diagnose and quantify the viral load from the infected tissues by designing an efficient PCR primer set. The developed PCR could detect the virus at 98% efficiency with 10 viral copy number as the limit of detection. The standard curve analysis and amplification arithmetics have shown that it can even detect even less than 10 copy numbers of virus in a sample. The standard curve of the assay has shown R2 value of 0.98 and slope of −3.3834 without any significant variations in inter- and intra- assays. The validated PCR primer pairs and developed SYBR green-based real-time PCR is highly specific, equally sensitive and comparatively economic than the existing TaqMan probe-based PCR for detection of IMNV.
•Validated a new set of PCR primers for SYBR green-based qPCR for the detection and quantification of IMNV infection in India•The developed PCR could detect the virus at 98% efficiency with 10 viral copy number as the limit of detection.•The standard curve of assay was showing an R2 value of 0.98 and a slope of −3.3834 without any statistical variations.•The assay can be implemented for the accurate diagnosis and viral load quantification of the IMNV from infected shrimps.
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