Short peptidoglycan recognition protein 5 modulates immune response to bacteria in Indian major carp, Cirrhinusmrigala

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 Zn2+, 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.

Gain of function studies on predicted host receptors for white spot virus

Three decades after its first outbreak, the shrimp white spot virus (WSV) is still a global cause of concern due to considerable losses and lack of effective control measures. Several candidate host receptor proteins have been identified, but the pathogenesis is not clearly understood, although the key role of the WSV envelope protein VP28 in virus internalization is established. Here, protein-protein docking is applied to evaluate the interaction of VP28 trimeric extracellular region with four host (Penaeus monodon) receptors reported earlier, Rab7 GTPase (PmRab7), glucose transporter 1 (PmGLUT1), C-type lectin (PmCTL) and calreticulin (PmCRT). The stability of predicted complexes evaluated in terms of binding energy per unit buried surface area ranged from -8.46 to -11.82 cal mol^-1/Ų, which is not sufficient for functional interaction. Nevertheless, each of these host proteins was tested by a gain-of-function approach by observing their ability to make a fish cell line permissive to the shrimp WSV. Full-length expression constructs of the four receptors were transfected into SSN1 snakehead fish cells that are non-permissive to WSV. Transfected SSN1 cells and WSV permissive insect Sf9 cells were challenged with purified WSV. After 24 h, the presence of receptor transcripts was confirmed in the treated SSN1 cells, and not in the non-transfected SSN1 cells. Further, vp28 transcript was detected in Sf9 cells, but not in any of the treated SSN1 cells, indicating that none of the receptors were singly sufficient to make SSN1 cells permissive to WSV, even though PmRab7 was a strong candidate that alone showed >85% protection in virus neutralization experiments. For the other 3 candidates, previous reports predicted the involvement of co-receptors, which is confirmed here by their inability to act singly.

Evaluation of the Binding Affinity of a Gonadotropin-Releasing Hormone Analogue (GnRH-a) Buserelin through In silico and In vivo Testing in Clarias magur

Aim:

To evaluate the binding affinity and biological potency of gonadotropin-releasing hormone analogue (GnRHa) Buserelin (C60H86N16O13) based on in silico and in vivo testing for induced breeding in Clarias magur.

Background:

Many attempts have been made to induce C. magur, but encouraging results have not yet been achieved. Hence, it is the need of the hour to find out more potent analogues or other bio-molecules for induced breeding in C. magur to facilitate sustainable aquaculture.

Objective:

To determine the binding affinity of C. magur GnRH receptor through in silico and to validate it for induced breeding of C. magur.

Methods:

Buserelin (C60H86N16O13) was selected as the potential GnRHa after screening several peptides for their binding energy with the C. magur GnRH receptor. The induced breeding trial was set up at ICAR-CIFE Powarkheda Centre, M.P. India, and Buserelin was administered in different doses to the brooders along with the dopamine inhibitor domperidone. The standard treatment with the commercial salmon GnRH (sGnRH) analogue Ovaprim® (Syndel, USA) was used as the control.

Results:

The 3-D structure of C. magur GnRH receptor was generated using MODELLER software. Molecular docking studies revealed the binding preference of the receptor as chicken (c) Gn- RH-II > Buserelin > sGnRH > catfish (cf) GnRH > human (m) GnRH. Though Buserelin showed better binding affinity compared to sGnRH, induced breeding experiments with magur showed similar performance of the ligands at the equivalent dose of 20 μg/kg B.W., but the spontaneous release of milt from the males was not observed in both cases. Significantly better reproductive parameters were recorded with Buserelin at the dose of 30 μg/kg B.W.

Conclusion:

The study revealed that that the GnRHa Buserelin can be used as an effective inducing agent for breeding in C. magur.

Development and characterization of a new DRCF cell line from Indian wild strain zebrafish Danio rerio (Hamilton 1822)

Danio rerio, zebrafish, has been widely used as a non-mammalian vertebrate model organism in various studies. The present research describes to develop and characterize a new cell line from a wild strain Indian zebrafish native to Brahmaputra River, Assam, India. The new cell line designated as DRCF was developed from the caudal fin of D. rerio. The cell line was successfully subcultured up to 31 passages. Growth studies revealed that cell growth of DRCF was optimal at 28 °C in L-15 medium supplemented with 20% FBS. Molecular characterization of the DRCF cell line using mitochondrial genes namely cytochrome oxidase subunit I gene (COI) and 16S rRNA authenticated the true origin of the cell line. The chromosome analysis of the DRCF cell line expressed its 50 diploid chromosome number of D. rerio. The immunocytochemical characterization of the cell line exhibited its fibroblastic morphology. The expression of the green fluorescent protein (GFP) following transfection revealed the suitability of the cell line for transfection studies.

Transcriptome analysis of Clarias magur brain and gonads suggests neuro-endocrine inhibition of milt release from captive GnRH-induced males

Transcriptome analysis of Clarias magur brain and gonads at preparatory, mature, 6 and 16 h post-GnRH injection (hpi) stages yielded 9.5 GB data with 39,738 contigs. Sequences of 45 reproductive genes were identified for the first time in C. magur along with unique and differentially expressed genes. The expression of 20 genes was validated by qRT-PCR. Upregulation of Cyp11A1, Cyp17A1 and FTZF1 genes in the 16hpi testis accompanied by the 17β-HSD3 expression indicates testosterone (T) synthesis in response to LH surge, while reduced expression of CYP11B1 suggests a high T: 11-KT ratio. It is evident by the gene expression analysis that the inhibitory neurotransmitter GABA, altered T: 11-KT, increased testicular bile acids, and oxytocin-like neuropeptide in the male brain, appear to be involved in arresting the pulsatile motion of testicular smooth muscles. The work generates important leads for an effective induced breeding strategy for silurid catfish.

Molecular characterization and expression analysis of secretory immunoglobulin M (IgM) heavy chain gene in rohu, Labeo rohita

Immunoglobulin M (IgM) is the major isotype among teleost immunoglobulins. The present study was aimed to explore IgM heavy chain gene and its expression profile in rohu. Full-length IgM heavy chain cDNA of rohu consisted of 1994 bp encoding a polypeptide of 576 amino acid residues including a leader peptide, variable (VH) and constant (CH1-CH2-CH3-CH4) domains confirming the secretory form of IgM. The sequence carries conserved residues such as cysteine, tryptophan and amino acid motifs like 'YYCAR' and 'FDYWGKGT-VTV-S'. The predicted 3 D model confirmed various domains of rohu IgM heavy chain. Phylogenetic tree analysis revealed that IgM heavy chain gene of rohu shared the same cluster with that of other cyprinid fishes. Tissue distribution analysis showed the predominant level of IgM heavy chain gene expression in kidney, spleen and intestine. IgM heavy chain gene expression in rohu kidney was found to be up-regulated and reached a maximum at 7 days post-challenge with Aeromonas hydrophila. These findings demonstrate the first report of full-length secretory IgM heavy chain gene in rohu. Besides, IgM heavy chain gene was highly expressed in major lymphoid tissues and bacterial challenge influenced its expression which further confirmed its role in the adaptive humoral immune response.

Regulation of compensatory growth by molecular mechanism in Labeo rohita juveniles under different feeding regimes

A study was carried out to assess the regulation of compensatory growth under different restriction feeding regimes in Labeo rohita juveniles by the interaction of various feed intake and growth regulating genes. A 60 day feeding trial was conducted with five treatment groups, Control (3% body weight, bw), T1 (alternate days), T2 (0.5% bw), T3 (1% bw) and T4 (2% bw) and feeding was done for first 30 days of the trial. For next 30 days, all the treatment groups were fed at a rate of 3% bw as in the control group. There was significant (p < 0.05) difference in the weight gain among the treatment groups with lowest FCR and highest PER was found in T2 group. Ghrelin gene mRNA levels were upregulated during first 30th days of the trial with highest expression levels in the T2 group. The expression levels of leptin gene mRNA were found significantly different (p < 0.05) among the treatments, which was down-regulated during initial 30 days and upregulated as the experiment progress towards 60th day. The IGF-1 mRNA expression levels were upregulated more in liver compared to the muscle tissue. The results of the study suggest that increased ghrelin levels and decreased leptin levels lead to hyperphagia during the onset of refeeding, which further triggers the compensatory growth in L. rohita. The present study describes the molecular mechanism behind the compensatory growth following a different feed restriction regime in L. rohita which is regulated due to the interaction of different energy homeostasis and growth regulating genes.

Complete mitochondrial genome of threatened mahseer Tor tor (Hamilton 1822) and its phylogenetic relationship within Cyprinidae family

The mahseers (Tor, Neolissochilus and Naziritor) are an important group of fishes endemic to Asia with the conservation status of most species evaluated as threatened. Conservation plans to revive these declining wild populations are hindered by unstable taxonomy. Molecular phylogeny studies with mitochondrial genome have been successfully used to reconstruct the phylogenetic tree and to resolve taxonomic ambiguity. In the present study, complete mitochondrial genome of Tor tor has been sequenced using ion torrent next-generation sequencing platform with coverage of more than 1000 x. Comparative mitogenome analysis shows higher divergence value at ND1 gene than COI gene. Further, occurrence of a distinct genetic lineage of T. tor is revealed. The phylogenetic relationship among mahseer group has been defined as Neolissochilus hexagonolepis ((T. sinensis (T. putitora, T. tor), (T. khudree, T. tambroides)).

Genetic diversity and demographic history of the giant river catfish Sperata seenghala inferred from mitochondrial DNA markers

The giant river catfish Sperata seenghala has huge demand in South Asian countries due to its low number of intramuscular bones and nutritive value. However, the culture practises for this fish have not been standardized and the current demand for this fish is being met by capture fisheries only. Unregulated and indiscriminate fishing would lead overexploitation of fish stocks subsequently stock depletion. Genetic diversity between populations would give insight about population structure and demography. In the present study, S. seenghala stocks from three rivers, namely Ganga, Brahmaputra and Mahanadi were characterized using cytochrome b gene and D-loop region. Moderate to high haplotype diversity and low nucleotide diversity values were observed in all populations. Analysis of molecular variance and pairwise F_ST values showed significant genetic differentiation among populations. Patterns of diversity, haplotype networks and mismatch distribution strongly suggest a historical influence on the genetic structure of S. seenghala populations. S. seenghala stocks from these three rivers are genetically distinct units and management measures should be formulated separately for each population.

Molecular characterization of kisspeptin gene and effect of nano-encapsulted kisspeptin-10 on reproductive maturation in Catla catla

Kisspeptin, a member of the RF-amide-related peptide family, has emerged recently as an essential gatekeeper of various reproductive processes via its ability to activate kisspeptin receptors at puberty. In this study, the kiss1 gene and its receptor kiss1rb were cloned and characterized from the brain of Catla catla. Further, the effects of kissppetin-10 (K-10) and chitosan-encapsulated K-10 nanoparticles (CK-10) on gene expression were assessed. The full-length complementary DNA sequence of kiss1 is 754 bp with an open reading frame of 351 bp that encodes a putative protein of 116 amino acids. The kiss1rb complementary DNA is 1,280 bp long and contains a 5'-untranslated region of 30 bp, 3'-untranslated region of 149 bp, and an open reading frame (open reading frame) of 1,101 bp. The expression patterns of kiss1 and kiss1rb messenger RNA (mRNA) in basal tissues revealed that they are mainly expressed in the brain, pituitary gland, and gonads. CK-10 nanoparticles with a particle size of 125 nm and a zeta potential of 36.45 mV were synthesized and compared with K-10. Chitosan nanoparticles showed 60% entrapment efficiency for K-10. The mRNA expression of reproductive genes (GnRH, LH, and FSH) in fish injected with K-10 declined after 6 h, whereas those injected with CK-10 showed controlled and a sustained surge of mRNA expression of these genes with a peak at 12 h. Histologic examination of ovaries indicated a pronounced effect of CK-10 on maturation and gonadal development. The study reports that this sustained release delivery system will help in increasing the half-life of K-10 and other therapeutic protein drugs in the biological system. Besides, the nanoformulation developed in the present study may be useful for developing therapies against various reproductive dysfunctions in vertebrates.

Assessment of DNA damage and molecular responses in Labeo rohita (Hamilton, 1822) following short-term exposure to silver nanoparticles

The increasing application of silver nanoparticles (Ag-NPs) both in industries and in agricultural fields has led to its accumulation in the aquatic ecosystem through water run-off. In the present study, the effects of Ag-NPs in the liver of Labeo rohita, were investigated at genomic and cellular level for seven days at the concentrations of 100, 200, 400 and 800 μg l(-1) by using 18 and 29 nm sizes of Ag-NPs. The Ag-NPs sizes of 18 and 29 nm were synthesized by a chemical method using atomic force microscopy with the zeta potential of -55 mV and-31.4 mV respectively. They were found to be spherical with smooth surfaces. Assessment of genotoxic effects of the particles in the fish using single-cell gel electrophoresis showed DNA damage on exposure to concentrations of 400 and 800 μg l(-1). Histopathological examination of the liver revealed vacuolar degeneration, hepatocytes have undergone total degeneration and high accumulation of Ag-NPs that depicted both time and dose-dependent relationships. Furthermore, the expression study of stress-related genes showed down-regulation, due to the production of free radicals and reactive oxygen species. Ag-NPs can cause both DNA damage and affect the cellular responses of L. rohita.

Report of leucine-rich repeats (LRRs) from Scylla serrata: Ontogeny, molecular cloning, characterization and expression analysis following ligand stimulation, and upon bacterial and viral infections

Leucine-rich repeat (LRR) proteins are present in all living organisms, and their participation in signal transduction and defense mechanisms has been elucidated in humans and mosquitoes. LRRs possibly involve in protein-protein interactions also and show differential expression pattern upon challenge with pathogens. In the present study, a new LRR gene was identified in mud crab, Scylla serrata. LRR gene mRNA levels in different developmental stages and various tissues of S. serrata were analysed. Further, the response of the gene against different ligands, Gram-negative bacterium, and white spot syndrome virus (WSSV) was investigated in vitro and in vivo. Full-length cDNA sequence of S. serrata LRR (SsLRR) was found to be 2290 nucleotide long with an open reading frame of 1893bp. SsLRR encodes for a protein containing 630 deduced amino acids with 17 conserved LRR domains and exhibits significant similarity with crustacean LRRs so that these could be clustered into a branch in the phylogenetic tree. SsLRR mRNA transcripts were detected in all the developmental stages (egg, Zoea1-5, megalopa and crab instar), haemocytes and various tissues such as, stomach, gill, muscle, hepatopancreas, hematopoietic organ, heart, epithelial layer and testis by reverse-transcriptase PCR. SsLRR transcripts in cultured haemocytes showed a 2-fold increase in expression at 1.5 and 12h upon Poly I:C induction. WSSV challenge resulted in significant early up-regulation at 3h in-vitro and late up-regulation at 72h in-vivo. Peptidoglycan (PGN)-induction resulted in marginal up-regulation of SsLRR at timepoints, 6, 12 and 24h (fold change below 1.5) and no significant change in the expression at early timepoints. LPS-stimulation, on the other hand, showed either down-regulation or normal level of expression at all timepoints. However, a delayed 5-fold up-regulation was observed in vivo against Vibrio parahaemolyticus infection at 72hpi. The constitutive expression of the LRR gene in all the early life-stages, and its response to various ligands and to viral challenge suggest the possible role of the LRR in immune defense in mud crab. The result provides additional information which would help in future studies in understanding the innate immune pathways in crustaceans.

Expression studies on NA+/K(+)-ATPase in gills of Penaeus monodon (Fabricius) acclimated to different salinities

The decapod crustacean Penaeus monodon survives large fluctuations in salinity through osmoregulation in which Na+/K(+)-ATPase (NKA) activity in the gills plays a central role. Adult P. monodon specimens were gradually acclimatized to 5, 25 and 35 per thousand salinities and maintained for 20 days to observe long-term alterations in NKA expression. Specific NKA activity assayed in gill tissues was found to be 3 folds higher at 5 per thousand compared to 25 per thousand (isosmotic salinity) and 0.48 folds lower at 35 per thousand. The enzyme was immunolocalized in gills using mouse α-5 monoclonal antibody that cross reacts with P. monodon NKA α-subunit. At 5 per thousand the immunopositive cells were distributed on lamellar tips and basal lamellar epithelium of the secondary gill filaments and their number was visibly higher. At both 25 per thousand and 35 per thousand NKA positive cells were observed in the inter-lamellar region but the expression was more pronounced at 25 per thousand. Gill architecture was normal at all salinities. However, the 1.5 fold increase in NKA α-subunit mRNA at 5 per thousand measured by quantitative RT-PCR (qRT-PCR) using EF1α as reference gene was not statistically significant. The study confirms the osmoregulating ability of P. monodon like other crustaceans at lower salinities. It is likely that significant increase in NKA transcript level happens at an earlier time point. At higher salinities all three methods record only marginal or no change from isosmotic controls confirming the hypothesis that the animal largely osmoconforms in hyperosmotic environment.

Molecular cloning, sequencing and tissue-level expression of complement C3 of Labeo rohita (Hamilton, 1822)

Complement component C3 plays a central role in all known complement activation pathways. In the present study, we cloned, sequenced and analyzed the full-length cDNA sequence of Labeo rohita complement C3 (LRC3). The expression pattern of complement C3 mRNA in different tissues of healthy rohu and after challenge with Aeromonas hydrophila were evaluated using real-time PCR. The LRC3 cDNA sequence of rohu comprised of 5081 bp encoding a predicted protein of 1645 amino acids. The deduced amino acid sequence had the characteristic domain architecture. About eight domains specific to complement C3 are present in the sequence starting from signal peptide to netrin C345C (NTR) domain. The post-translational processing signal sequence (RKRR), the C3-convertase cleavage site sequence (LAR) and the canonical thiol-ester motif (GCGEQ) were found to be conserved in the LRC3. Real-time PCR analysis revealed the highest expression of C3 in liver and extra-hepatic expression of C3 was also observed in all the tissues studied. A. hydrophila challenge resulted in significant up-regulated expression of C3 transcripts in both liver and kidney at 6, 12, 24, 48 and 72 h post-infection.

Development of chitosan conjugated DNA vaccine against nodavirus in Macrobrachium rosenbergii (De Man, 1879)

The protective efficacy of a DNA construct containing extra small virus antisense (XSVAS) gene of nodavirus encapsulated with chitosan nanoparticles (NPs) was investigated in giant freshwater prawn Macrobrachium rosenbergii (De Man, 1879). The delivery was carried out using oral and immersion methods. A plasmid concentration of 100 ng μL(-1) when conjugated with chitosan NPs was found to be more effective in increasing the survivability of the infected prawn. The particle mean size, zeta potential and loading efficiency percentage were 297 nm, 27 mV and 85%, respectively. The ability of the chitosan to form a complex with the plasmid was studied by agarose gel electrophoresis. The NPs were characterized by atomic force microscopy (AFM). Persistence study showed the presence of the DNA construct up to 30th day post-treatment. The oral treatment was found to be better than the immersion treatment for delivery of the chitosan-conjugated DNA construct. This is probably the first report on the delivery of nanoconjugated DNA construct in M. rosenbergii, against nodavirus.

DNA barcoding of elasmobranchs from Indian coast and its reliability in delineating geographically widespread specimens

Identification of elasmobranchs by conventional taxonomy is difficult due to similarities in morphological characters. Species-specific molecular markers are good choice for identifying species irrespective of it's life stage. Recently, mitochondrial cytochrome c oxidase subunit I (COI) gene got global recognition as a barcode gene to discriminate all animals up-to species level. In this study, mitochondrial COI partial gene was used to develop DNA barcodes for 18 species of elasmobranchs (10 species of sharks and 8 species of rays). The COI barcodes clearly distinguished all the species with high interspecific distance values than intraspecific values. The average interspecific and intraspecific distance values are 8.6% and 0.3% for sharks, respectively and 12.4% and 0.63% for rays, respectively using K2P method. The Neighbor-Joining tree showed distinct clusters shared by the species of same genera. The COI barcodes were also used to estimate allopatric divergences for selected species across broad geographical locations and found that Sphyrna lewini, Aetobatus narinari and Neotrygon kuhlii have cryptic diversity.

White spot syndrome virus Manipulates Ubiquitin Gene Expression in Penaeus monodon

The present study reports the effect of WSSV on the expression profiles of shrimp ubiquitin gene both at protein and transcript levels at different time points after infection. A gradual decrease in ubiquitin protein levels was observed till 12 hpi (0.25 and 0.23 μg/mg of the total protein in gills and muscle, respectively) with a sudden increase at 18 hpi (1.86 and 1.8 μg/mg of total protein in gills and muscle, respectively). The RT-PCR results showed a gradual decrease in ubiquitin mRNA levels in gill tissue till 12 hpi while a more or less constant mRNA levels were observed in muscle tissue till 12 hpi. However, a fourfold and 16 fold induction in ubiquitin mRNA levels at 18 hpi in gill and muscle, respectively suggests its possible regulation by WSSV in the manifestation of the disease.

A GFP-based bacterial biosensor with chromosomally integrated sensing cassette for quantitative detection of Hg(II) in environment

A mercury biosensor was constructed by integrating biosensor genetic elements into E. coli JM109 chromosome in a single copy number, using the attP/attB recombination mechanism of lambda phage. The genetic elements used include a regulatory protein gene (merR) along with operator/promoter (O/P) derived from the mercury resistance operon from pDU1358 plasmid of Serratia marcescens. The expression of reporter gene gfp is also controlled by merR/O/P. Integration of the construct into the chromosome was done to increase the stability and precision of the biosensor. This biosensor could detect Hg(II) ions in the concentration range of 100-1700 nmol/L, and manifest the result as the expression of GFP. The GFP expression was significantly different (P < or = 0.05) for each concentration of inducing Hg(II) ions in the detection range, which reduces the chances of misinterpretation of results. A model using regression method was also derived for the quantification of the concentration of Hg(II) in water samples.

Protection of Penaeus monodon from Infection of White spot syndrome virus by DNA Construct Expressing Long Hairpin-RNA Against ICP11 Gene

A plasmid construct (pICP11-LH) was designed to constitutively express long-hairpin RNA (lhRNA) against icp11 gene, which is reportedly the most highly expressed gene of White spot syndrome virus (WSSV) and likely to have an important role in viral pathogenesis. The construct was used singly and in combination with other similar constructs designed against vp28 and vp19. A total of 6 treatments, T1 (pICP11-LH; 35 μg), T2 (pVP28-LH; 35 μg), T3 (pVP28-LH and pVP19-LH; 17.5 μg each), T4 (pVP28-LH and pVP19-LH; 25 μg:10 μg), T5 (pICP11-LH, pVP28-LH and pVP19-LH; 11.5 μg each) and T6 (pGFP-LH; 35 μg) were injected intramuscularly into 20 g Penaeus monodon specimens. The shrimp were challenged with WSSV 24 hpi and protection efficacy was measured in terms of survival and viral load 15 days after challenge. Appropriate negative and positive controls were used. T2 and T3 offered highest protection (75%) followed by T1 (67%) and T4 and T5 groups (58%), while T6 showed 25% protection. In all the target specific treatments, the viral load as estimated by single tube WSSV kit was kept in check (10-100 copies), whereas in the unimmunized challenged controls it progressed to severe infection (>10(5) copies). In spite of over 3 times higher expression of ICP11 compared to VP28, its knockdown by pICP11-LH did not offer any protective advantage over pVP28-LH, either singly or in combination. Moreover, none of the combinations bettered the protection efficacy of pVP28-LH administered alone. To investigate concerns about deleterious effect of plasmid persistence and constitutive expression on shrimp growth, a lab-scale 1 month growth study was conducted with 4 treatments T2, T3, T4 and T6, where no difference in specific growth rate was observed compared to controls.

RNA interference-based therapeutics for shrimp viral diseases

RNA interference (RNAi) has emerged as a powerful tool to manipulate gene expression in the laboratory. The presence of a double-stranded RNA (dsRNA) in eukaryotic cells triggers this post-transcriptional gene-silencing mechanism, leading to a sequence-specific degradation of the target mRNA. Among its many potential biomedical applications, silencing of viral genes stands out as a promising therapeutic strategy. Marine shrimp viral diseases, especially white spot disease (WSD), represents one of the most attractive targets for the development of therapeutic RNAi owing to its widespread economic impact. This review summarizes the current knowledge in the therapeutic application of RNAi for combating viral diseases in shrimp. The basic principles of RNAi are described, focusing on features important for its therapeutic manipulation. Subsequently, a stepwise strategy for the development of therapeutic RNAi is presented.