•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.
Interferon regulatory factor (IRF) 3 and IRF7 are key regulators of type I interferon (IFN) gene expression for the antiviral immune response. In the present study, interferon regulatory factor 3 and ...7 from Asian seabass, namely AsIRF3 and AsIRF7 were cloned and characterized. The full-length cDNA sequence of IRF3 and IRF7 consisted of 2965 and 2343 bp respectively. AsIRF3 and AsIRF7 were true orthologes of vertebrate IRF3/7 and showed similar domain organization, with an N-terminal DBD which consisted five tryptophan residues in IRF3 and four in IRF7, a C-terminal IRF3 domain and a serine rich region. Both IRF3 and 7 constitutively expressed during the ontogenesis and in all tissues of healthy fish. The expression of both genes was up-regulated following NNV challenge with obvious transcript abundance in brain heart and kidney. Ectopic expression of AsIRF3 and AsIRF7 displayed activation of ISRE/NF-κB promoters and modulation of interferon, ISGs and pro-inflammatory cytokine gene expression. These observations indicated that IRF3 and IRF7 play an important role in Asian seabass's antiviral defense and the RIG-IRF-IFN axis is conserved in the species.
•The 61 kDa MAVS orthologue from Asian seabass conferred its localization to mitochondria.•Ectopic expression of LcMAVS demonstrated a potent antiviral activity against nervous necrosis virus causing the viral RDRP transcription.•MAVS over expression increased the activity of ISRE promoter in vitro by 52 folds.•LcMAVS transient over expression triggered IFN stimulatory genes viz, IRF-3, ISG-15, and Mx.
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.
A 90‐day experiment was conducted by rearing 1020 prawn juveniles (0.54 ± 0.03 g) in water supplemented with three different concentrations of probiotic bacteria viz. T1 (10⁷ cfu L⁻¹), T2 ...(10⁸ cfu L⁻¹), T3 (10⁹ cfu L⁻¹) and the control (C) (unsupplemented water), to evaluate probiotic effect of Lactobacillus plantarum. In the present study, the growth parameters (WG%, SGR) and feed utilization parameters (FCR, PER) significantly improved (P < 0.05) in T3. The growth and feed utilization parameters though improved marginally in T1 and T2, the difference was not significant (P > 0.05) compared to the control. The gastro‐intestinal Lactobacillus sp. count increased significantly (P < 0.05) in all the treatment groups, whereas the decrease in harmful bacteria was significant (P < 0.05) in T3 compared to the control. Similarly, the Lactobacillus sp. count in culture water increased significantly (P < 0.05) in all the experimental groups, whereas the decrease in harmful bacteria was significant (P < 0.05) in T2 and T3. The immune parameters (THC, PO and RB activity) and clearance efficiency significantly improved (P < 0.05) in T3 with concurrent decrease (P < 0.05) in cumulative mortality against Aeromonas hydrophila challenge. However, water quality did not improved (P > 0.05) in any of the treatment groups. The results indicate that Lactobacillus plantarum at a minimum concentration of 10⁹ cfu L⁻¹ could be used as water additive to confer its probiotic effect in prawn, Macrobrachium rosenbergii. Moreover, future studies with higher probiotic concentrations should be conducted for its efficient commercial scale field application.
Bacillus subtilis, a Gram-positive, aerobic, endospore-forming bacterium, was evaluated for its probiotic potential in Indian major carp, Labeo rohita. Labeo rohita (15±2 g) were fed a feed ...containing B. subtilis in three concentrations for 2 weeks, e.g., 0.5 (T₂), 1.0 (T₃) and 1.5 (T₄) x 10⁷ CFU g⁻¹ feed. The control group (T₁) was fed feed without B. subtilis for the same period. Haematological and serum parameters were monitored at weekly intervals. The response variables were total erythrocyte count, total leucocyte count (TLC), haemoglobin, total protein, albumin, globulin, albumin-globulin ratio, alkaline phosphatase activity, alanine aminotransferase activity and aspartate aminotransferase activity. Fish were challenged intraperitoneally with a virulent strain of Aeromonas hydrophila after 2 weeks of feeding to the treatment groups and positive control group, while the negative control group was challenged with phosphate-buffered saline only. Clinical signs and symptoms, and mortality/survival percentage were noted in each group. The haematological and serum parameters were monitored each week and during post challenge on the third and tenth day. The B. subtilis-treated fish (T₄, 1.5 x 10⁷ CFU g⁻¹ feed) showed maximum per cent survival (87.50%), weight gain (35.5%), TLCs (3.23 x 10⁴ cells mm⁻³), haemoglobin content (7.4 g%), total protein (2.37 gdL⁻¹) and globulin content (1.28 g dL⁻¹) during the pre-challenge. Enzymes showed higher activities during post challenge (P<0.05). The result suggests that B. subtilis can be used effectively as a commercial product for use in aquaculture.
Abstract
The COVID-19 pandemic presents a serious public health challenge in all countries. However, repercussions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on future ...global health are still being investigated, including the pandemic’s potential effect on the emergence and spread of global antimicrobial resistance (AMR). Critically ill COVID-19 patients may develop severe complications, which may predispose patients to infection with nosocomial bacterial and/or fungal pathogens, requiring the extensive use of antibiotics. However, antibiotics may also be inappropriately used in milder cases of COVID-19 infection. Further, concerns such as increased biocide use, antimicrobial stewardship/infection control, AMR awareness, the need for diagnostics (including rapid and point-of-care diagnostics) and the usefulness of vaccination could all be components shaping the influence of the COVID-19 pandemic. In this publication, the authors present a brief overview of the COVID-19 pandemic and associated issues that could influence the pandemic’s effect on global AMR.
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