Mitochondrial antiviral signaling protein (MAVS), an innate immune signaling adapter coordinates the signals received from two independent cytosolic pathogen recognition receptors (RIG-1 and MDA5) to ...induce antiviral genes. In the present study the MAVS gene of Lates calcarifer (LcMAVS) was cloned and characterized. The complete cDNA sequence of LcMAVS was 3160 bp and encodes a poly peptide of 577 amino acids. Structural analysis of LcMAVS revealed an N-terminal CARD-like domain, central proline-rich domain and a C-terminal transmembrane domain. Phylogenetic analysis indicated that LcMAVS exhibited the closest relationship to P. olivaceous MAVS. LcMAVS was ubiquitously expressed in all tested tissues of healthy fish viz., brain, gill, heart, liver, spleen, kidney and intestine, with highest transcript level in spleen. The mRNA transcript level of LcMAVS in different developmental stages showed constitutive expression in all the stages tested suggesting the maternal transfer of the gene. Significant up regulation in MAVS expression was observed post nervous necrosis virus (NNV) challenge in vivo in all the selected tissues. Further, time course analysis showed that LcMAVS transcripts significantly increased in the brain and spleen tissues after NNV infection. These findings provide useful information for further elucidating the function of LcMAVS in antiviral innate immune response against NNV in Asian seabass.
•The MAVS gene of Lates calcarifer (LcMAVS) was cloned and characterized.•Phylogenetic analysis indicated that LcMAVS exhibited the closest relationship to P. olivaceous MAVS. LcMAVS was ubiquitously expressed in all tested tissues of healthy fish viz., brain, gill, heart, liver, spleen, kidney and intestine, with highest transcript level in spleen.•The mRNA transcript level of LcMAVS in different developmental stages showed constitutive expression in all the stages tested suggesting the maternal transfer of the gene.•The time course analysis showed that LcMAVS transcripts significantly increased in the brain and spleen tissues after NNV infection.•The findings provide useful information for further elucidating the function of LcMAVS in antiviral innate immune response against NNV in Asian seabass.
Emerging and re-emerging diseases in fish cause drastic economic losses in the aquaculture sector. To combat the impact of disease outbreaks and prevent the emergence of infections in culture ...systems, understanding the advanced strategies for protecting fish against infections is inevitable in fish health research. Therefore, the present study aimed to evaluate the induction of trained immunity and its protective efficacy against Streptococcus agalactiae in tilapia. For this, Nile tilapia and the Tilapia head kidney macrophage primary culture were primed using β-glucan @200 μg/10 g body weight and 10 μg/mL respectively. Expression profiles of the markers of trained immunity and production of metabolites were monitored at different time points, post-priming and training, which depicted enhanced responsiveness. Higher lactate and lactate dehydrogenase (LDH) production in vitro suggests heightened glycolysis induced by priming of the cells using β-glucan. A survival rate of 60% was observed in β-glucan trained fish post challenge with virulent S. agalactiae at an LD50 of 2.6 × 107 cfu/ml, providing valuable insights into promising strategies of trained immunity for combating infections in fish.
•Innate immune training using β-glucan can elevate cytokine transcript levels.•Expression of trained immunity markers, mTOR and HIF1α elevated post immune training with β-glucan in tilapia.•Higher lactate and LDH production post β-glucan induction in the supernatant of tilapia head kidney macrophage culture.•Survival rate of 60% in Streptococcus agalactiae-challenged immune trained tilapia.
The synthesis of silver nanoparticles has gained interest due to their diverse applications in various fields. It is very essential to use capping agents to avoid loss of nanosized characteristics ...due to agglomeration of AgNPs. In the present investigation, a simple and environmentally viable protocol to synthesize a wide range of concentrations of non-agglomerated and colloidal AgNPs using extracts of discarded wastes (gills and intestine) of Tilapia (Oreochromis mossambicus) in three different aqueous media without the requirement of any additional stabilizing and capping agent is described. The size of most of AgNPs ranged from 2 to 20 nm, followed by sizes of 20-40 nm and some with sizes of 40-50 nm. Zeta potential was in the range of −31.1 to −52.8 mV and −33.3 to −53.6 mV, and surface plasmon resonance ranged from 405 to 410 nm for gill and intestine extracts respectively. HR-TEM images indicated that Phosphate buffer saline is the best suitable for synthesizing non-agglomerated AgNPs capped with biomolecules. Valorization has been achieved by trapping Ag NPs into two different forms of natural zeolites namely stilbite and mordenite and their ammonia removal efficiency have been evaluated. In addition, the antimicrobial activity of synthesized AgNPs and their valorized products exhibited potent inhibitory activity against test bacteria such as Escherichia coli and Aeromonas hydrophila. This study not only establishes a simple and environmentally viable protocol for the synthesis of AgNPs and valorized products for environmental and disease management but also adds to the utilization of fish wastes in solid waste management.
Multi-drug resistance (MDR) in bacteria is regarded as an emerging pollutant in different food production avenues including aquaculture. One hundred and sixty out of 2304 bacterial isolates from ...shrimp farm samples (
n
= 192) of Andhra Pradesh, India, were MDR. Based on biochemical identification and 16S rRNA sequencing, they were grouped into 35 bacterial species with the predominance of
Vibrio parahaemolyticus
(12.5%). The MDR isolates showed highest resistance toward oxytetracycline (89%) with more than 0.2 MAR (multiple antibiotic resistance), demonstrates a high-risk source. The most prevalent antibiotic-resistance gene (ARG) and mobile genetic element (MGE) detected were
tetA
(47.5%) and
int1
(46.2%), respectively. In conjugation experiments, overall transfer frequency was found to be in the range of 1.1 × 10
−9
to 1.8 × 10
−3
with the transconjugants harbouring ARGs and MGEs. This study exposed the wide distribution of MDR bacteria in shrimp and its environment, which can further aggravate the already raised concerns of antibiotic residues in the absence of proper mitigation measures.
TLR5 is one of the important PRR (pathogen recognition receptors) and plays a fundamental role in pathogen recognition and activation of innate immune responses. It recognizes bacterial flagellin and ...stimulates the production of proinflammatory cytokines, through signalling via the adaptor protein MyD88. In this study, we characterized partial TLR5 (soluble form) gene from Pangasianodon hypophthalmus and analysed its expression profile upon challenge by Edwardsiella tarda. Bioinformatic analysis of gene sequence revealed a putative protein of 266 amino acids with four Leucine rich repeats. Quantitative expression analysis of TLR 5S showed its wide distribution in various organs and tissues. However, significant expression of TLR5S was observed in liver and spleen at 12 h (∼207.8 fold, p < 0.05). Significant upregulation was observed in kidney at 72 h.p.i. (50 folds, p < 0.05) indicating that the kidney provides longer protection almost till the activation of the adaptive immune system. This study enriches the knowledge of TLR5S in boosting the innate immunity against bacterial invasion in fish.
•We identified and partially characterized the Toll like receptor 5 in P. hypophthalmus.•The catfish TLR 5 gene is variously expressed in different immune organs at different time intervals against E. tarda infection.•We studied histopathological changes in various tissues of catfish against E. tarda infection.
An 18-months field trial was performed to explore the effect of duration of stunting on growth, digestive enzymes and carcass quality in Chanos chanos. Milkfish fry (weight of 1.25 ± 0.03 g and ...length of 5.53 ± 0.03 cm) were stocked in earthen ponds of 0.02 ha, in triplicate, for different duration of stunting, viz., 4 months (Treatment-1; T4), 8 months (Treatment-2; T8) and 12 months (Treatment-3; T12) and a normal seed (Control; C) separately. In the stunting phase, fish were stocked at higher stocking density (0.2 million/ha) and fed de-oiled rice bran at sub-optimal level. Post-stunting or re-feeding phase commenced immediately after completion of respective stunting duration and fish were reared for the rest of the period to complete the total rearing period of 18 months. In post-stunting, fish stocking density was adjusted to (5000 pieces/ha) and fed at an optimum level (3%). At the end of stunting phase, the study found a significant reduction in growth, survival, digestive enzymes activity, except protease in the T4 group, and carcass nutrients composition of stunted fish. However, in the initial phase of post-stunting, T8 group exhibited an elevated specific growth rate (5.00 ± 0.092%/day), body weight gain (80.82 ± 1.28 g), amylase (0.585 ± 0.021 U/mg protein), protease (5.48 ± 0.13 U/mg protein), and lipase activity (7.92 ± 0.32 U/mg protein). All stunted fish groups displayed a compensatory growth response in post-stunting, but a complete growth compensation was observed in T8 group, which resulted in better feed conversion ratio (3.03 ± 0.04) feed efficiency ratio (0.33 ± 0.01), protein efficiency ratio (1.91 ± 0.03), survival (91.38 ± 0.07%) and digestive enzyme activities. Similarly, at the end of post-stunting, carcass analysis revealed a complete restoration of nutrients in stunted fish and significantly higher protein content in T8 group. Further, the study found lower meat and higher bone contents in normally reared fish than the post-stunted fish which revealed the carcass quality improvement in post-stunted fish thus indicates superiority of the stunting process over normal rearing. Overall, the study suggests that stunting of milkfish, for 8 months (T8), positively affects its growth, survival, digestive enzyme activities and carcass quality which in turn, shall help to overcome the contemporary challenges in milkfish culture.
The innate immune signaling adapter, Mitochondrial antiviral signaling protein (MAVS) coordinates the signals received from two independent RLRs (RIG-1 and MDA5) to induce IFN & interferon ...stimulatory genes (ISGs). In the present study, we report identification of an orthologue of MAVS from Lates calcarifer (LcMAVS) and its functional role in piscine RLR signaling. The LcMAVS-cDNA was cloned into pcDNA and transfected into SISS cells. LcMAVS was detected to be a 61KDa protein in western blot. Confocal microscopy demonstrated the mitochondrial localization of LcMAVS. In addition, pcDNA-MAVS transfected cells were protected against Nervous Necrosis Virus (NNV) infection as manifested by the delayed appearance of cytopathic effect (CPE) and decreased viral transcript levels. Ectopic expression of LcMAVS resulted in activation of an ISRE-containing promoter (52 folds over control cells) as well as transcriptional expression of IRF-3, IFN-1 and IFN-inducible genes including Mx and ISG15 (p<0.05). These results suggest that LcMAVS is involved in the antiviral immunity as one of the adaptors in fish IFN-activation pathway.
•The 61kDa MAVS orthologue from Asian seabass conferred its localization to mitochondria.•Ectopic expression of LcMAVS demonstrated a potent antiviral activity against NNV 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.
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