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Our work evaluated the possible underlying roles of dietary dried seaweed (Gracilaria verrucosa; GV) on the inherent immune response, antioxidant capacity, immune-related gene expression, and protection of whiteleg shrimp (Litopenaeus vannamei) contra white spot syndrome virus (WSSV). Three hundred and sixty healthy L. vannamei (15.26 g ± 1.29 g) were graded into four supplemental groups (Triplicate/group) and fed with diets including 0 (control), 2, 4, and 8 g GV (kg diet) −1 for 21 days. Following the feeding period, each group of shrimp received an intramuscular WSSV injection (1.4 × 106 copies/ml). Hemolymph and gills samples were collected before and after the challenge with WSSV. Notably, the administration of dietary GV significantly enhanced the innate immune parameters of pacific white shrimp including total hemocyte count (THC), phagocytosis, phenoloxidase activity, reactive oxygen species (ROS) production, and lysozyme activity before and after challenge with WSSV. Additionally, dietary supplementation of 4, and 8 g of GV (kg diet)−1 remarkably elevated ACP, AKP, SOD, GPx, and catalase activities along with a decrease in the MDA level in gills of shrimp before and post-WSSV challenge. In response to the GV supplement, significant upregulation of expression of ALF1, CRU1, PEN4, and CTL with downregulation of TRAF6, STAT, TLR1, and NOS genes was recorded in the gills tissue before and post-challenge with WSSV, especially at a dose of 8.0 GV g kg − 1. Dietary inoculated shrimp with GV revealed notably higher survival percentages after being challenged with WSSV. Conclusively, these data indicate that Gracilaria verrucosa can be recommended as a valuable supplemented seaweed to stimulate the innate immunity and enhance the health of Litopenaeus vannamei against viral infection. [ABSTRACT FROM AUTHOR]

Simple Summary: Shrimp lack an adaptive immune system, which makes the oral delivery of antibodies a potential therapeutic strategy for treating diseases in these animals. Single-domain antibodies (sdAbs) derived from camelids against the white spot syndrome virus exhibit promising therapeutic potential for disease prevention and treatment, and they have emerged as effective feed additives in shrimp diets. The results of the present study demonstrated that the inclusion of sdAbs did not negatively affect juvenile whiteleg shrimp at the organism and tissue levels; however, it did impact molecular pathways associated with growth, cold stress, and antioxidant responses. A six-week feeding trial was conducted to assess the safety of single-domain antibodies (sdAbs) derived from camelids against the white spot syndrome virus (WSSV) (WSSVvp28 was used as the antigen), focusing on the whole-organism responses and molecular-level changes in juvenile whiteleg shrimp (Litopenaeus vannamei). Five experimental diets with varying levels of sdAbs were formulated: CON (no sdAb supplementation); SDA8.2 (8.20% of sdAbs); SDA16.4 (16.40% of sdAbs); SDA24.6 (24.60% of sdAbs); and SDA32.8 (32.80% of sdAbs). In the CON diet, 450 mL of water per kg of diet (45%) was used to form a feed dough, while sdAbs were used to replace the water in the treatment diets. A total of 450 shrimp, with an initial body weight of 3.27 ± 0.02 g (mean ± SEM), were randomly distributed in 15 tanks (30 shrimp per tank; three tanks per treatment). Each tank was filled with 30 L of seawater (77 L capacity) in an indoor semi-recirculating system with a constant water flow rate of 1.2 L min−1. The photoperiod was maintained at 12 h of light and 12 h of dark. The water temperature, pH, salinity, and dissolved oxygen were 27.3 ± 0.1 °C, 7.61 ± 0.01, 34 ± 1 ppt, and 5.94 ± 0.04 mg L−1, respectively. During the feeding trial, the shrimp were fed the experimental diet (40% protein and 11% lipid) three times a day for six weeks. Following the feeding trial, an acute cold-water-temperature stress test was conducted by abruptly exposing the shrimp from each treatment to 15 °C for 4 h, down from 27 °C. The results showed no significant differences in the growth performance (weight gain, feed utilization efficiency, survival, etc.), plasma metabolites (aspartate aminotransferase activity, alanine aminotransferase activity, total protein, and glucose), or antioxidant enzymes (superoxide dismutase and glutathione peroxidase) among all the experimental diets (p > 0.05). In the acute cold-temperature stress test, there was no significant interaction between sdAb supplementation and temperature stress, nor any main effect from either factor, except for the main effect of temperature stress on the glucose levels, which was significantly higher in shrimp exposed to cold-temperature stress (p < 0.05). The next-generation sequencing of differentially expressed genes (DEGs) in the hepatopancreases of shrimp fed the CON, SDA16.4, and SDA32.8 diets, followed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses, indicated that DEGs were significantly enriched in signaling pathways associated with growth, cold stress, and antioxidant systems. Overall, the results from conventional measurements suggest that the use of sdAbs against the WSSV may be safe for juvenile whiteleg shrimp. However, findings from the sophisticated analysis indicate that further research is needed to understand the molecular mechanisms underlying the observed changes, and to evaluate the long-term effects of sdAb supplementation in shrimp diets. [ABSTRACT FROM AUTHOR]

Simple Summary: The outbreak of white spot syndrome poses a significant threat to the shrimp farming industry. To explore the interaction between Litopenaeus vannamei and the pathogenic white spot syndrome virus (WSSV), this study cloned and analyzed an important pattern recognition receptor, the C-type lectin ladderlectin (LvLL). The results revealed that LvLL in L. vannamei promoted WSSV replication, thereby affecting shrimp survival rates. This study demonstrated the role of LvLL in the resistance of L. vannamei to WSSV, providing theoretical insights into the mechanisms of shrimp resistance to the virus. C-type lectins are known for agglutination activity and play crucial roles in regulating the prophenoloxidase (proPO) activation system, enhancing phagocytosis and encapsulation, synthesizing antimicrobial peptides, and mediating antiviral immune responses. This work cloned a C-type lectin, ladderlectin (LvLL), from Litopenaeus vannamei. LvLL comprised a 531 bp open reading frame (ORF) that encoded 176 amino acids. The predicted LvLL protein included a signal peptide and a CLECT domain. LvLL was predicted to feature a transmembrane region, suggesting it may be a transmembrane protein. LvLL was predominantly expressed in the shrimp's hepatopancreas. After WSSV infection, LvLL expression in the hepatopancreas increased significantly by 11.35-fold after 228 h, indicating a general upregulation. Knockdown of LvLL resulted in a significant decrease in WSSV viral load and a notable increase in shrimp survival rates. Additionally, knockdown of LvLL led to a significant downregulation of apoptosis-related genes Bcl-2 and caspase 8 and a significant upregulation of p53 and proPO in WSSV-infected shrimp. This study showed that LvLL played a vital role in the interaction between L. vannamei and WSSV. [ABSTRACT FROM AUTHOR]

Taura syndrome in shrimp, caused by Taura syndrome virus (TSV), is a disease listed by the World Organisation for Animal Health (OIE) that has been identified in five continents, causing serious economic losses in years. Due to the lack of specific drugs available to treat Taura syndrome, an effective TSV detection method is urgently needed to ensure pathogen prediction and disease control. In this study, we developed and evaluated an isothermal enzymatic recombinase amplification–based assay (TSV-ERA) that was able to diagnose TSV within 20 min at an optimal temperature of 42 °C. In the reaction system, the optimal concentrations of the primer and the probe were 500 nM and 120 nM, respectively. When the plasmid standards were used as a detection template, the check-out time of TSV-ERA was 12 min (21.76 ± 0.60 Ct), and the limit of detection (LOD) was 3.6 × 101 copies/µL. Compared to the sensitivity of the TSV detection method recommended by the OIE, TSV-ERA was equal to real-time PCR (qPCR) and higher than one-step PCR. This assay was highly specific for TSV and had no cross-reactivity with Enterocytozoon hepatopenaei (EHP), white spot syndrome virus (WSSV), Vibrio parahaemolyticus strain causing acute hepatopancreatic necrosis disease (VpAHPND), infectious hypodermal and hematopoietic necrosis virus (IHHNV), and the genomic DNA of specific pathogen-free (SPF) shrimp. Compared with the common detection methods, the TSV-ERA assay was able to shorten the detection time and decrease the detection temperature while sustaining accurate sensitivity. Based on these results, our TSV-ERA detection method is simple, rapid, and effective, and has great potential in the detection of TSV. [ABSTRACT FROM AUTHOR]

As a member of the small G protein superfamily, ras-related nuclear proteins (Ran) mainly function in regulating nucleocytoplasmic transport and microtubule formation. Ran is reported to have an immune function in invertebrate defense against pathogen invasion. This study obtained the full-length sequence of the Ran cDNA (PcRan) of Procambarus clarkii and investigated changes in its expression after pathogenic infection and its role in the clearance of pathogenic bacteria. Phylogenetic tree analysis revealed that PcRan and Ran of other crustaceans belong to one branch and have a close genetic relationship. Multiple sequence alignment analyses revealed that PcRan has a highly conserved G domain and contains all the G1–G5 motifs. PcRan expression was widely distributed in various tissues in P. clarkii, with the highest expression levels being found in the muscle and gills. The levels of PcRan expression in several major immune organs, including hepatopancreas, gills, hemocytes, and intestines, were significantly increased after infection with white spot syndrome virus or Aeromonas veronii. After PcRan overexpression, the bacterial clearance ability and survival rate of P. clarkii infected with A. veronii was significantly higher than that of the control group. This study showed that PcRan is involved in the innate immune process of P. clarkii. The results of this study provide theoretical significance and application value for understanding the immune function of Ran after crayfish pathogen infection, and provide guidance for the prevention and control of crayfish diseases. [ABSTRACT FROM AUTHOR]

As a newly discovered virus, Decapoda iridovirus 1 (DIV1) can cause a mortality rate of up to 100% in crustaceans, leading to huge economic losses. At present, there is no effective prevention and control measures for this disease. In the present study, the specific primers targeting highly conserved regions of MCP gene were designed, and then a quantitative real-time PCR method was established. The results indicate that DIV1 quantitative real-time PCR established has good specificity and does not cross react with other pathogens including white spot syndrome virus (WSSV), infectious subcutaneous and hematopoietic necrosis virus (IHHNV) and Vibrio parahaemolyticus induced acute hepatopancreatic necrosis disease (VpAHPND). The real-time PCR was capable of detecting DIV1 DNA at a minimum concentration of 10 copies/µL within 34 cycles. The method has good repeatability, with intra group and inter group coefficients of variation both less than 2%. Thirty-two clinical samples were assessed using both the real-time PCR and conventional PCR. The results shown real-time PCR we established are more sensitive than conventional PCR. In conclusion, this method has strong specificity, stable repeatability, and high sensitivity, providing technical support for clinical diagnosis, epidemiology investigation and monitoring of DIV1. [ABSTRACT FROM AUTHOR]

Chinese rice‐field eels rhabdovirus (CrERV) causes haemorrhagic disease in Chinese rice‐field eels (Monopterus albus), leading to significant mortality and economic losses. Sensitive detection of CrERV nucleic acids is essential to control the spread of this pathogen and to treat infected individuals. Herein, we developed an efficient and sensitive droplet digital PCR (ddPCR) method to rapidly detect and quantify CrERV. The ddPCR assay optimal conditions were an annealing temperature of 53°C, and primer and probe concentrations of 0.5 and 0.25 μM, respectively. The assay had a diagnostic sensitivity of 0.23 copies/μL, and was highly specific, showing no cross reactivity with other viruses (infectious haematopoietic necrosis virus, grass carp reovirus, spring viremia of carp virus, largemouth bass ranavirus, carp edema virus, Chinese giant salamander iridovirus, and white spot syndrome virus). Real‐time quantitative PCR testing of 30 Chinese rice‐field eels samples detected CrERV in 7 samples (23.3%), whereas ddPCR detected CrERV in 12 samples (40%), demonstrating its higher sensitivity. Thus, ddPCR represents an advanced method to absolutely quantify CrERV in infected fish with low virus concentrations, providing a valuable tool to manage the spread and impact of CrERV. [ABSTRACT FROM AUTHOR]

Penaeus vannamei, also known as white foot shrimp, is globally one of the three high-yield shrimp farming varieties. The wild species is found along the Pacific coast of South America. Since 1988, China has introduced P. vannamei. Due to its strong environmental adaptability, high feed conversion rate, fast growth rate, and high tolerance to ammonia nitrogen and nitrite, it has been widely promoted in aquaculture. By 2021, the aquaculture output of P. vannamei in China reached 1.977 million tons, accounting for approximately 37% of the world's total production, and has extremely high economic value.Growth traits are among the most important economic factors in the production of P. vannamei. With the intensive development of shrimp farming and degradation of germplasm, the white spot syndrome virus (WSSV) is a serious disease faced by the global shrimp industry. The infection can cause symptoms such as reduced food intake, enlarged liver and pancreas, pale red body color, and white spots on the head and chest armor in shrimp, resulting in widespread death.At present, China has cultivated 12 new varieties of P. vannamei, which to some extent alleviates its dependence on imports for high-quality P. vannamei. However, the excellent traits of domestic shrimp species are singular, and cultivating new varieties of P. vannamei with fast growth and strong disease resistance is an urgent demand in the market. Genetic parameter evaluation is the fundamental work of selection breeding. Heritability reflects the genetic variation in traits in the breeding population, which is of great significance in the development of a selection index, prediction of selection response, comparison of selection methods, selection breeding planning, and other breeding processes. There are different degrees of genetic correlation among various quantitative traits of shrimp, and genetic correlation coefficients are important for selecting target traits. The estimation of genetic correlation can be used to develop a comprehensive selection index and breeding program of multiple traits, which can improve the selection efficiency and breed better varieties with multiple traits. The higher the genetic correlation between traits, the better the effect of indirect selection. The estimation of genetic parameters is greatly affected by the test population, breeding management, analysis methods, and other factors. To ensure the accuracy of multi-trait composite breeding for growth and WSSV resistance, accurate evaluation of growth and WSSV resistance needs to be carried out for specific breeding populations. There are two commonly used target traits for measuring WSSV resistance in P. vannamei: individual survival time after infection and half-lethal survival rate (SS50) of families. In practice, measuring the half-lethal survival rate of families is more convenient. However, the correlation between these two traits has not yet been reported.To promote the growth and WSSV resistance of P. vannamei, 59 families (1, 770 individuals) were tested for WSSV infection. We recorded the survival time and individual body length of shrimp after infection and analyzed the mean, standard deviation, maximum and minimum values, and coefficient of variation of half-lethal survival rate and test traits for each line. The heritability and genetic correlation coefficients of growth, survival time, and half-lethal survival rate were calculated. Variance components and genetic parameters for growth and survival traits were estimated using a two-trait animal model and a sire-dam threshold model. The genetic parameters of body length were corrected by including age as a covariate. The genetic parameters of WSSV survival time were corrected by including body length as a covariate. The estimated heritability of body length was medium (0.17±0.05), and the estimated heritabilities of survival time and half-lethal survival rate were medium (0.18±0.05 and 0.14±0.05). Further, the estimated heritabilities of the three traits were significantly different from zero (P < 0.01). The genetic correlation between body length and survival time and that of body length and half-lethal survival rate were low (0.15±0.20 and 0.25±0.22). There were no significant differences between the genetic correlations and zero (P > 0.05). The genetic correlation between survival time and half-lethal survival rate was high (0.96±0.03). There was no significant difference between the genetic correlation and one (P > 0.05). The results showed that a comprehensive selection index of growth and WSSV resistance of P. vannamei can be established to carry out multi-trait composite breeding. In this breeding population, the growth and WSSV resistance of P. vannamei can be combined with multiple traits according to the breeding requirements, and the comprehensive selection index can be formulated by assigning values. In addition, to optimize the breeding of each generation, the half-lethal survival rate of WSSV can be used as an indicator of WSSV resistance. This study provides basic data and theoretical support for breeding varieties of P. vannamei with excellent growth and WSSV resistance.

This document is a correction notice for an article titled "Effect of prawn fed with Catharanthus roseus ethanolic extract incorporated diet in the protein profile approaches in gene expressions related and immune characteristics in giant freshwater prawn (Macrobrachium rosenbergii)." The original article contained mistakes, specifically in the figures and author contributions. The corrected figures include a GC-MS peak level graph, conformational transitions in VP28 protein, and relative mRNA expression levels of certain genes. Additionally, the author contributions were updated to include Velusamy Gayathri. The corrected version of the article has been approved. [Extracted from the article]

Plants have long been the main focus of the medical industries' attention due to their extensive list of biological and therapeutic properties and ethnobotanical applications. This study investigates the effects of substituting Catharanthus roseus, a medicinal herb favorable in the diet of post larvae (PL) of Macrobrachium rosenbergii, a freshwater prawn. The study assesses the impact on the GC-MS, UV–Vis analyses, and FTIR spectrum through leaf material from C. roseus that was analyzed and found to include a variety of phytochemicals including four of the seven secondary metabolic products discovered in C. roseus leaves showed bioactive principles 2-methylmannoside, squalene, pentatriacontane, and 2,4,4-trimethyl-3-hydroxymethyl-5a-(3-methyl-but-2-enyl)-cyclohexene. Catharanthus roseus is rich in the anticancer compounds vinblastine and vincristine. After that, the compounds undergo molecular in silico assessments docking studies revealed that among these compounds with bioactive properties. After separation, the basal diets of C. roseus crude extract in various ratios 0.5 mg/g, 1 mg/g, 1.5 mg/g, and 2 mg/g for 90 days experimental prides Macrobrachium rosenbergii was fed a diet enriched with C. roseus. At the conclusion of the feeding trial, it was discovered that the C. roseus supplemented feed given prawns had considerably (P < 0.05) greater physiological water parameters such as temperature, pH, salinity, dissolved oxygen, ammonia, and total dissolved solids, have to be within tolerance ranges so as to get the most effective results for M. rosenbergii. The muscle of protein profile such as a white spot disease (WSD) is caused by the white spot syndrome virus (WSSV), which also requires amino acid (AA) and fatty acid (FA); protein VP28 fused was shown to bind to prawn cells in an in vitro binding experiment using Western blot SDS-PAGE gel. Moreover, a respective up- and downregulated crustacean hyperglycemic hormone (MrCHH), myostatin (MrMSTN), peroxidasin (MrPXDN), heat shock protein 70 (MrHSP70), and heat shock protein 90 (MrHSP90) confirmed the impact of C. roseus on prawn development. The prawns that were given a diet containing a 1.5 mg/g concentration of C. roseus feed showed significant enhancements in safe level growth performance. Therefore, the present study proposes that 1.5 mg/g may be used as a dietary supplement safe level for regulating Macrobrachium rosenbergii production more effectively. [ABSTRACT FROM AUTHOR]

The shrimp farming sector has faced significant hurdles due to acute hepatopancreatic necrosis disease (AHPND). In this study, an attempt was made to combine the enzymatic recombinase amplification (ERA) assay and CRISPR-Cas12a (ERA-Cas12a) for the rapid detection of AHPND. A set of crRNA and ssDNA with high sensitivity and good specificity was screened, and the best optimized one-tube system was obtained. Our additional analysis focused on the sensitivity and specificity of ERA-Cas12a, contrasting it with the established methodology of the World Organization for Animal Health (WOAH). The ERA-Cas12a could deliver the desired outcomes in under 40 min with a detection limit of 2 × 103 copies/µL and showed no interaction with white spot syndrome virus (WSSV), infectious hypodermal and hematopoietic necrosis virus (IHHNV), Enterocytozoon hepatopenaei (EHP), Taura syndrome virus (TSV), covert mortality nodavirus (CMNV), and decapod iridescent virus 1 (DIV1). Our actual sample detection results showed that the ERA-Cas12a system has the advantage of being more intuitive and fast without losing too much sensitivity compared with the nested PCR and quantitative real-time PCR (qPCR). Moreover, the detection results could be directly observed under blue light irradiation. All these results indicate that ERA-Cas12a provides a rapid and specific diagnosis of AHPND, which could further reduce the dependence on the instrument and effectively reduce aerosol pollution. It could be helpful in the prevention of shrimp disease and in reducing the economic loss of shrimp aquaculture. [ABSTRACT FROM AUTHOR]

As "non‐cellular organisms", viruses need to infect living cells to survive themselves. The virus infection must alter host's metabolisms. However, the influence of the metabolites from the altered metabolisms of virus‐infected host cells on virus‐host interactions remains largely unclear. To address this issue, shrimp, a representative species of crustaceans, is challenged with white spot syndrome virus (WSSV) in this study. The in vivo results presented that the WSSV infection enhanced shrimp glycolysis, leading to the accumulation of lactate. The lactate accumulation in turn promoted the site‐specific histone lactylation (H3K18la and H4K12la) in a p300/HDAC1/HDAC3‐dependent manner. H3K18la and H4K12la are enriched in the promoters of 75 target genes, of which the H3K18la and H4K12la modification upregulated the expression of ribosomal protein S6 kinases 2 (S6K2) in the virus‐infected hosts to promote the virus infection. Further data revealed that the virus‐encoded miR‐N20 targeted hypoxia inducible factor‐1α (HIF‐1α) to inhibit the host glycolysis, leading to the suppression of H3K18la and H4K12la. Therefore, the findings contributed novel insights into the effects and the underlying mechanism of the virus‐induced histone lactylation on the virus‐host interactions, providing new targets for the control of virus infection. [ABSTRACT FROM AUTHOR]

This study aimed to assess the genetic parameters associated with survival against acute hepatopancreatic necrosis (S_AHPND) and white spot syndrome virus (S_WSSV) in controlled challenge settings, as well as survival in commercial ponds (S_COMERCIAL) and within a high biosecurity genetic nucleus (S_NUCLEUS). Two lines were studied: one with a history of resistance to WSSV (RES) and another focused on rapid growth but susceptible to WSSV (GRO). All traits were analyzed as binary (alive or dead), and (co)variance components were estimated using a within-line multivariate linear animal model. Heritabilities for S_AHPND and S_WSSV ranged from 0.09 to 0.15 and from 0.01 to 0.14, respectively. In the case of S_COMMERCIAL, heritabilities spanned from 0.01 to 0.23, and for S_NUCLEUS, they were between 0.02 and 0.08. Notably, genetic correlations (rg) between S_WSSV and S_AHPND exceeded 0.50 in both lines. When examining S_COMMERCIAL, rg with S_AHPND in GRO were estimated at values between 0.25 and 0.51, while in RES, they ranged from 0.23 to 0.62. Regarding S_WSSV, rg ranged from − 0.04 to 0.60 in GRO and from 0.22 to 0.76 in RES. The rg between S_NUCLEUS and the other traits fell within the range of − 0.15 to 0.74. Spearman correlations between the family breeding values for all four traits were estimated to be between 0.31 and 0.66. In summary, this study found that additive genetic variation for these traits ranged from low to moderate. The results suggest the potential for a correlated response in overall commercial survival (S_COMERCIAL) when selecting for improved specific-pathogen resistance against both S_AHPND and S_WSSV. [ABSTRACT FROM AUTHOR]

Nanotechnology can contribute significantly to the aquaculture sector for a wide range of applications. In this study, silica nanoparticles were prepared from beach sand and characterized. The XRD pattern was obtained and confirms the crystalline nature of potassium aluminium silicate [K(AlSi3O8)], sodium silicate (Na2Si2O5), and silicon dioxide (SiO2). FTIR confirms that intense peaks at 445, 795, and 1036 cm−1 are characteristic of Si–O–Si stretching vibration. TEM micrograph of silica nanoparticles found a spherical morphology with an average size of 42 nm. In vitro anti-WSSV (white spot syndrome virus) activity was carried out using PmLyo-Sf9 cells by attachment inhibitory and virucidal activity; the optimum concentration was determined as 320 μg/mL. The interaction of silica nanoparticles and VP28 envelope protein was confirmed using in silico approach. The complexes K(AlSi3O8)-VP28, Na2Si2O5-VP28, and SiO2-VP28 had binding affinities of −5.2, −7.2, and −8.3 Kcal/mol, respectively. [ABSTRACT FROM AUTHOR]

Tiny controllers referred to as microRNAs (miRNAs) impede the expression of genes to modulate biological processes. In invertebrates, particularly in shrimp as a model organism, it has been demonstrated that miRNAs play a crucial role in modulating innate immune responses against viral infection. By analyzing small RNAs, we identified 60 differentially expressed miRNAs (DEMs) in Penaues vannamei hemocytes following infection with white spot syndrome virus (WSSV). We predicted the target genes of WSSV-responsive miRNAs, shedding light on their participation in diverse biological pathways. We are particularly intrigued by pva-miR-166, which is the most notably elevated miRNA among 60 DEMs. At 24 h post-infection (hpi), the negative correlation between the expression of pva-miR-166 and its target gene, PvProsaposin, was evident and their interaction was confirmed by a reduction in luciferase activity in vitro. Suppression of PvProsaposin in unchallenged shrimp led to decreased survival rates, reduced total hemocyte count (THC), and increased caspase 3/7 activity, suggesting its significant role in maintaining hemocyte homeostasis. In WSSV-infected shrimp, a lower number of hemocytes corresponded to a lower WSSV load, but higher shrimp mortality was observed when PvProsaposin was suppressed. Conformingly, the introduction of the pva-miR-166 mimic to WSSV-infected shrimp resulted in decreased levels of PvProsaposin transcripts, a significant loss of THC, and an increase in the hemocyte apoptosis. Taken together, we propose that pva-miR-166 modulates hemocyte homeostasis during WSSV infection by suppressing the PvProsaposin, an anti-apoptotic gene. PvProsaposin inhibition disrupts hemocyte homeostasis, rendering the shrimp’s inability to withstand WSSV invasion. IMPORTANCE Gene regulation by microRNAs (miRNAs) has been reported during viral infection. Furthermore, hemocytes serve a dual role, not only producing various immune-related molecules to combat viral infections but also acting as a viral replication site. Maintaining hemocyte homeostasis is pivotal for the shrimp’s survival during infection. The upregulated miRNA pva-miR-166 could repress PvProsaposin expression in shrimp hemocytes infected with WSSV. The significance of PvProsaposin in maintaining hemocyte homeostasis via apoptosis led to reduced survival rate, decreased total hemocyte numbers, and elevated caspase 3/7 activity in PvProsaposin-silenced shrimp. Additionally, the inhibitory ability of pva-miR-166-mimic and dsRNA-PvProsaposin on the expression of PvProsaposin also lowered the THC, increases the hemocyte apoptosis, resulting in a lower WSSV copy number. Ultimately, the dysregulation of the anti-apoptotic gene PvProsaposin by pva-miR-166 during WSSV infection disrupts hemocyte homeostasis, leading to an immunocompromised state in shrimp, rendering them incapable of surviving WSSV invasion. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) presents a considerable peril to the aquaculture sector, leading to notable financial consequences on a global scale. Previous studies have identified hub proteins, including WSSV051 and WSSV517, as essential binding elements in the protein interaction network of WSSV. This work further investigates the functional structures and potential applications of WSSV hub complexes in managing WSSV infection. Using computational methodologies, we have successfully generated comprehensive three-dimensional (3D) representations of hub proteins along with their three mutual binding counterparts, elucidating crucial interaction locations. The results of our study indicate that the WSSV051 hub protein demonstrates higher binding energy than WSSV517. Moreover, a unique motif, denoted as "S-S-x(5)-S-x(2)-P," was discovered among the binding proteins. This pattern perhaps contributes to the detection of partners by the hub proteins of WSSV. An antiviral strategy targeting WSSV hub proteins was demonstrated through the oral administration of dual hub double-stranded RNAs to the black tiger shrimp, Penaeus monodon, followed by a challenge assay. The findings demonstrate a decrease in shrimp mortality and a cessation of WSSV multiplication. In conclusion, our research unveils the structural features and dynamic interactions of hub complexes, shedding light on their significance in the WSSV protein network. This highlights the potential of hub protein-based interventions to mitigate the impact of WSSV infection in aquaculture. [ABSTRACT FROM AUTHOR]

Aims This study aimed to assess the effects of chlorine dioxide (ClO2) in water on whiteleg shrimp Penaeus vannamei , evaluating its impact on the stomach microbiota, gill transcriptome, and pathogens. Methods and results ClO2 was added to the aquarium tanks containing the shrimp. The application of ClO2 to rearing water was lethal to shrimp at concentrations above 1.2 ppm. On the other hand, most of the shrimp survived at 1.0 ppm of ClO2. Microbiome analysis showed that ClO2 administration at 1.0 ppm significantly reduced the α-diversity of bacterial community composition in the shrimp stomach, and this condition persisted for at least 7 days. Transcriptome analysis of shrimp gill revealed that ClO2 treatment caused massive change of the gene expression profile, including stress response genes. However, after 7 days of the treatment, the gene expression profile was similar to that of shrimp in the untreated control group, suggesting a recovery to the normal state. This 1.0-ppm ClO2 significantly reduced shrimp mortality in artificial challenges with an acute hepatopancreatic necrosis disease-causing Vibrio parahaemolyticus and white spot syndrome virus, which were added to rearing water. Conclusions The use of ClO2 at appropriate concentrations effectively eliminates a significant portion of the bacteria in the shrimp stomach and pathogens in the water. The results of this study provide fundamental knowledge on the disinfection of pathogens in water using ClO2 and the creation of semi germ-free shrimp, which has significantly decreased microbiome in the stomach. [ABSTRACT FROM AUTHOR]

The objective of this study was to define desired genetic gains from economically important traits of Pacific white shrimp (Litopenaeus vannamei) using participatory approaches. Two questionnaires were sent out to 100 Pacific white shrimp farmers in all five Iranian shrimp farming provinces. Questionnaire A (Q‐A) includes management factors and farming environments. Moreover, in this questionnaire, farmers were asked to rank the fourth most important traits in shrimp among 10 economic traits in the list for genetic improvement. In questionnaire B (Q‐B), priorities of the four traits with the highest value were obtained using pairwise comparison. The results showed that the four most important traits were white spot syndrome virus resistance (WSSV), growth rate before 4 months (GR), acute hepatopancreatic necrosis disease resistance (AHPND), and female total weight at ablation (FTW). Medians of the best individual preference values were WSSV (0.222), GR (0.173), AHPND (0.157), and FTW (0.053). Most disagreements were found between the social group preference values in the commercial products and water salinity categories. Desired genetic gains were 1.71%, 1.57%, 0.53% and 0.31% for GR, AHPND, WSSV and FTW, respectively. This study highlighted that despite environmental and management differences, participatory approaches can achieve desired genetic results for Pacific white shrimp breeding programme. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV), the causative agent of White spot disease (WSD), not only caused huge economic losses, but also greatly limited the development of crustacean breeding industry. Chinese herbs are widely used and have great application potential in antiviral research. In thist study, the antiviral effects of 11 Chinese herb extracts were evaluated in Procambarus clarkii (crayfish) model of WSSV infection, among which Cimicifuga foetida L. extract showed the highest inhibition rate (88.22%) against WSSV replication. On this basis, the anti-WSSV effect of Isoferulic acid (IFA), a major bioactive component of Cimicifuga foetida L., was further investigated. The results showed that IFA significantly inhibited WSSV replication (96.57%, 50 mg/kg) in a dosedependent manner and significantly improved the survival of WSSV-challenged crayfish. IFA had the potential preventive and therapeutic effect against WSSV infection, and the preventive effect was better than the therapeutic effect. Mechanistically, IFA suppressed the expression of the immediate early gene ie1, the DNA polymerase gene DNApol and envelope protein gene Vp28 to inhibit WSSV replication, activated TLR, CTL and ProPo genes expression to block ie1 transcription, and suppressed BAF, STAT, NF-κb and Crustin 1 genes expression to elevate innate immunity against WSSV infection. Besides, IFA upregulated the cMnSOD, mMnSOD, CAT and GST genes expression, and downregulated the COX-1 and COX-2 genes expression to balance the oxidative stress and inflammatory damage caused by WSSV infection. This study provides a theoretical basis and meaningful reference for the development of IFA as a highly effective and practical anti-WSSV drug. [ABSTRACT FROM AUTHOR]

The cellular endosomal sorting complex required for transport (ESCRT) system comprises five distinct components and is involved in many different physiological processes. Recent studies have shown that different viruses rely upon the host ESCRT system for viral infection. However, whether this system is involved in white spot syndrome virus (WSSV) infection remains unclear. Here, we identified 24 homologs of ESCRT subunits in kuruma shrimp, Marsupenaeus japonicus, and found that some key components were strongly upregulated in shrimp after WSSV infection. Knockdown of key components of the ESCRT system using RNA interference inhibited virus replication, suggesting that the ESCRT system is beneficial for WSSV infection. We further focused on TSG101, a crucial member of the ESCRT-I family that plays a central role in recognizing cargo and activating the ESCRT-II and ESCRT-III complexes. TSG101 colocalized with WSSV in hemocytes. The addition of N16 (a TSG101 inhibitor) markedly decreased WSSV replication. TSG101 and ALIX of the ESCRT system interact with WSSV envelope proteins. The host proteins TSG101, RAB5, and RAB7, the viral protein VP28, and DNA were detected in endosomes isolated from hemocytes of WSSV-infected shrimp. Knockdown of Rab5 and Rab7 expression reduced viral replication. Taken together, these results suggest that the ESCRT system is hijacked by WSSV for transport through the early to late endosome pathway. Our work identified a novel requirement for the intracellular trafficking and infection of WSSV, and provided novel therapeutic targets for the prevention and control of WSSV in shrimp aquaculture. IMPORTANCE Viruses utilize the ESCRT machinery in a variety of strategies for their replication and infection. This study revealed that the interaction of ESCRT complexes with WSSV envelope proteins plays a crucial role in WSSV infection in shrimp. The ESCRT system is conserved in the shrimp Marsupenaeus japonicus, and 24 homologs of the ESCRT system were identified in the shrimp. WSSV exploits the ESCRT system for transport and propagation via the interaction of envelope proteins with host TSG101 and ALIX in an endosome pathway-dependent manner. Understanding the underlying mechanisms of WSSV infection is important for disease control and breeding in shrimp aquaculture. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to estimate genetic parameters of growth traits and resistance to white spot syndrome virus in Pacific white shrimp (Litopenaeus vannamei). Through controlled virus challenge assays, phenotypic values for five traits were assessed: body weight, overall length, body length, tail length, and post-infection survival time. Three models were utilized, namely pedigree-based best linear unbiased prediction, genomic best linear unbiased prediction, and single-step genomic best linear unbiased prediction. Under the genomic prediction model, the heritability of growth-related traits decreased, whereas the heritability of post-infection survival time increased. Both genomic models significantly enhanced prediction accuracy compared to the pedigree-based model, with the most notable improvement observed in virus resistance. The genetic correlations between growth and WSSV resistance obtained from the three methods were consistently low and negative. These findings provide valuable insights for breeding programs and variety development in L. vannamei. The current study aimed to provide a precise assessment of the genetic parameters associated with growth and white spot syndrome virus (WSSV) resistance traits in Pacific white shrimp (Litopenaeus vannamei). This was achieved through a controlled WSSV challenge assay and the analysis of phenotypic values of five traits: body weight (BW), overall length (OL), body length (BL), tail length (TL), and survival hour post-infection (HPI). The analysis included test data from a total of 1017 individuals belonging to 20 families, of which 293 individuals underwent whole-genome resequencing, resulting in 18,137,179 high-quality SNP loci being obtained. Three methods, including pedigree-based best linear unbiased prediction (pBLUP), genomic best linear unbiased prediction (GBLUP), and single-step genomic BLUP (ssGBLUP) were utilized. Compared to the pBLUP model, the heritability of growth-related traits obtained from GBLUP and ssGBLUP was lower, whereas the heritability of WSSV resistance was higher. Both the GBLUP and ssGBLUP models significantly enhanced prediction accuracy. Specifically, the GBLUP model improved the prediction accuracy of BW, OL, BL, TL, and HPI by 4.77%, 21.93%, 19.73%, 19.34%, and 63.44%, respectively. Similarly, the ssGBLUP model improved prediction accuracy by 10.07%, 25.44%, 25.72%, 19.34%, and 122.58%, respectively. The WSSV resistance trait demonstrated the most substantial enhancement using both genomic prediction models, followed by body size traits (e.g., OL, BL, and TL), with BW showing the least improvement. Furthermore, the choice of models minimally impacted the assessment of genetic and phenotypic correlations. Genetic correlations among growth traits ranged from 0.767 to 0.999 across models, indicating high levels of positive correlations. Genetic correlations between growth and WSSV resistance traits ranged from (−0.198) to (−0.019), indicating low levels of negative correlations. This study assured significant advantages of the GBLUP and ssGBLUP models over the pBLUP model in the genetic parameter estimation of growth and WSSV resistance in L. vannamei, providing a foundation for further breeding programs. [ABSTRACT FROM AUTHOR]

This article presents a new method for detecting Decapod iridescent virus 1 (DIV1), a harmful pathogen in crustacean farming. The method, called TaqMan-based real-time PCR, is highly accurate and specific for detecting aquatic viruses. The study developed primers and a probe targeting the DIV1 gene and tested the assay's specificity and sensitivity. The results showed that the method was highly specific and could detect very low levels of DIV1 DNA. The authors recommend using this method alongside another real-time PCR method for the best detection of DIV1. [Extracted from the article]

The arthropod exoskeleton provides protection and support and is vital for survival and adaption. The integrity and mechanical properties of the exoskeleton are often impaired after pathogenic infection; however, the detailed mechanism by which infection affects the exoskeleton remains largely unknown. Here, we report that the damage to the shrimp exoskeleton is caused by modulation of host lipid profiles after infection with white spot syndrome virus (WSSV). WSSV infection disrupts the mechanical performance of the exoskeleton by inducing the expression of a chitinase (Chi2) in the sub-cuticle epidermis and decreasing the cuticle chitin content. The induction of Chi2 expression is mediated by a nuclear receptor that can be activated by certain enriched long-chain saturated fatty acids after infection. The damage to the exoskeleton, an aftereffect of the induction of host lipogenesis by WSSV, significantly impairs the motor ability of shrimp. Blocking the WSSV-caused lipogenesis restored the mechanical performance of the cuticle and improved the motor ability of infected shrimp. Therefore, this study reveals a mechanism by which WSSV infection modulates shrimp internal metabolism resulting in phenotypic impairment, and provides new insights into the interactions between the arthropod host and virus. Author summary: Loosening and softening of the exoskeleton of shrimp is frequently observed after white spot syndrome virus (WSSV) infection. This study reveals that the impairment of the exoskeleton is due to the enrichment of certain long-chain fatty acids (LCFAs), induction of chitinase, and ultimately decrease in cuticle chitin after WSSV infection. The exoskeleton allows for movement through contracting connected muscle; therefore, these WSSV-induced changes impair the motor ability of infected shrimp. The impaired motor ability may increase the chance of an infected shrimp being consumed by a healthy shrimp, thereby facilitating the natural transmission of WSSV. As WSSV exploits LCFAs for virion morphogenesis, we also show that blocking WSSV-induced lipogenesis restores exoskeleton performance, providing a possible strategy for the inhibition of viral transmission. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is causing significant economic losses in shrimp farming. Envelope proteins, which interact with host cells during viral attachment, are potential targets for drug development. In this study, the antiviral activity of Sargassum wightii was assessed using in-vitro and in-silico analyses. Crabs were injected with S. wightii extract and WSSV and were observed for 30 days post-infection. The antiviral activity was confirmed by bio-assay, histopathology, and in-silico analysis. GC–MS analysis identified 15 compounds in S. wightii, and in-silico docking revealed a strong interaction between VP28 and VP26 envelope proteins and stigmasta-4,22-dien-3-one. Molecular simulations validated the stability of the protein–ligand binding. These findings confirm the potential of S. wightii as a treatment for WSSV. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is marked as one of the most economically devastating pathogens in shrimp aquaculture worldwide. Infection of cultured shrimp can lead to mass mortality (up to 100%). Although progress has been made, our understanding of WSSV's infection process and the virus–host–environment interaction is far from complete. This in turn hinders the development of effective mitigation strategies against WSSV. Infection models occupy a crucial first step in the research flow that tries to elucidate the infectious disease process to develop new antiviral treatments. Moreover, since the establishment of continuous shrimp cell lines is a work in progress, the development and use of standardized in vivo infection models that reflect the host–pathogen interaction in shrimp is a necessity. This review critically examines key aspects of in vivo WSSV infection model development that are often overlooked, such as standardization, (post)larval quality, inoculum type and choice of inoculation procedure, housing conditions, and shrimp welfare considerations. Furthermore, the usefulness of experimental infection models for different lines of WSSV research will be discussed with the aim to aid researchers when choosing a suitable model for their research needs. [ABSTRACT FROM AUTHOR]

Biomarkers for monitoring shrimp health have been proposed but scarcely evaluated at the farm level. We analyzed several indicators of energy status in shrimp under farming conditions concerning stocking densities (100 m-2 with biofloc, 15 and 7 m-2). The influence of the year's season (temperature) was also analyzed, and, finally, an unfortunate event of White spot syndrome virus (WSSV) infection occurred on the 7 m-2 farms, adding another condition. At shrimp sampling from ponds, the effect of acute handling stress was also analyzed for indicators typically affected by such procedure with a 3- and 10-fold increase in glucose and lactate levels in hemolymph, respectively, regardless of density. This response was partially blunted at lower temperatures and WSSV incidence. Increased levels of protein in the hepatopancreas, adenylic energy charge (AEC) in both hepatopancreas and muscle and phosphagens in muscle were observed in shrimp from the 100 m-2 farms, suggesting a better nutritional and energetic status in shrimp cultured at high density with biofloc technology. Shrimp with WSSV presented lower hemocyanin levels in hemolymph, most likely associated with its role in the immune response. In WSSV-infected shrimp, the stress response regarding glucose increase was blunted, whereas a stress-induced increase in triglycerides (TG) levels in hemolymph was observed only with WSSV. Increased TG levels in those shrimp hepatopancreas could indicate a switch from carbohydrate to lipid-based metabolism associated with the preferential use of carbohydrates (Warburg effect) for virus replication in the early infection state. [ABSTRACT FROM AUTHOR]

The Pacific white shrimp, Penaeus vannamei, is highly susceptible to white spot syndrome virus (WSSV). Our study explored the transcriptomic responses of P. vannamei from resistant and susceptible families, uncovering distinct expression patterns after WSSV infection. The analysis revealed a higher number of differentially expressed genes (DEGs) in the susceptible family following WSSV infection compared to the resistant family, when both were evaluated against their respective control groups, indicating that the host resistance of the family line influences the transcriptome. The results also showed that subsequent to an identical duration following WSSV infection, there were more DEGs in P. vannamei with a high viral load than in those with a low viral load. To identify common transcriptomic responses, we profiled DEGs across families at 96 and 228 h post-infection (hpi). The analysis yielded 64 up-regulated and 37 down-regulated DEGs at 96 hpi, with 33 up-regulated and 34 down-regulated DEGs at 228 hpi, showcasing the dynamics of the transcriptomic response over time. Real-time RT-PCR assays confirmed significant DEG expression changes post-infection. Our results offer new insights into shrimp's molecular defense mechanisms against WSSV. [ABSTRACT FROM AUTHOR]

A permanent cell line, SPB (Snubnose pompano brain) was established from Trachinotus blochii by the explant culture method. It has been sub‐cultured more than 75 passages and showed optimal growth at 28°C using L‐15 medium supplemented with 15% to 20% FBS. The SPB cells were cryopreserved at different passage levels for various applications. SPB cells were composed of fibroblastic and epithelial‐like cells. The SPB cells were tested for mycoplasma contamination which was found to be negative. The origin of the SPB cell line from T. blochii was confirmed by amplification of the mitochondrial cytochrome oxidase I (COI) gene. The transfection efficiency of SPB cell line is 15% assessed by expression of green fluorescent protein using pEGFP‐N1 plasmid. In addition, two CMV promotor plasmids pFNCPE42‐DNA and pcDNAVP28 were transfected to SPB cells and it shows high expression levels of FNCP of fish nodavirus and VP28 protein of white spot syndrome virus by immunostaining. The SPB cells showed susceptibility to SJNNV and the infection was confirmed by RT‐PCR, Western blot, ELISA, TCID50 and RT‐qPCR. Experimental infection was carried out in T. blochii using SJNNV propagated in SPB cell line and found 100% mortality with clinical signs. The infection was confirmed by RT‐PCR. The SPB cell line can be used for propagation of fish viral pathogens and production of the recombinant proteins. [ABSTRACT FROM AUTHOR]

Simple Summary: Outbreaks of white spot disease in Pacific white shrimp pose a significant threat to the major shrimp farming industry. Understanding the mechanisms of the shrimp against the causative virus is crucial. C-type lectins are important pattern recognition receptors that can be involved in the response against viral infections. This study identified the C-type lectin domain family 4 member F in shrimp as an important receptor gene that could promote replication of the causative virus and affect the survival rate of shrimp. This study will provide a theoretical basis for understanding the resistance mechanisms of shrimp against the virus. White spot disease (WSD) outbreaks pose a significant threat to the Pacific white shrimp (Litopenaeus vannamei) farming industry. The causative agent is the white spot syndrome virus (WSSV). There are no effective treatments for WSD so far. Therefore, understanding the resistance mechanisms of L. vannamei against the WSSV is crucial. C-type lectins (CTLs) are important pattern recognition receptors (PRRs) that promote agglutination, phagocytosis, encapsulation, bacteriostasis, and antiviral infections. This study cloned the C-type lectin domain family 4 member F (LvCLEC4F) from L. vannamei. LvCLEC4F contains a 492 bp open reading frame (ORF) encoding a protein of 163 amino acids, including a carbohydrate recognition domain (CRD). Following a challenge with the WSSV, the expression profile of LvCLEC4F was significantly altered. Using RNA interference (RNAi) technology, it was found that LvCLEC4F promotes WSSV replication and affects the expression levels of genes related to the regulation of apoptosis, signaling and cellular stress response, and immune defense. Meanwhile, the hemolymph agglutination phenomenon in vivo was weakened when LvCLEC4F was knocked down. These results indicated that LvCLEC4F may play an important role in the interaction between L. vannamei and WSSV. [ABSTRACT FROM AUTHOR]

Shrimp aquaculture is the fastest-growing animal food-producing sector in the world due to its high demand in developed countries. The white spot syndrome virus (WSSV), a double-stranded virus, is primarily associated with high mortalities in the shrimp population, causing an imbalance in the aquaculture industry. Nanotechnology is advantageous due to its high surface area to volume ratio, targeted drug load and alteration of the charge of nanoparticle surface area, and prevention of adverse effects associated with commercial drug treatment. This review discusses the antiviral activity of chitosan triphosphate (CS/TPP)-coated nanoparticles encapsulating WSSV Viral protein 28 (VP28), innate immunity stimulation using polyamine-coated carbon quantum dots, and the investigation of silver nanoparticle designed Argovit-4 with or without PVP responsible for inhibiting viral activity. Nanotechnology-driven techniques have improved the stability of RNA-induced vaccines, paving the way for an effective cure for white spot syndrome. [ABSTRACT FROM AUTHOR]

It is reported that ILF2 (interleukin enhancer binding factor 2) is involved in the immune response by regulating the transcription of interleukin 2 (IL2), which may play an important role in host-virus interactions. To investigate the role of ILF2 in WSSV infection in Penaeus japonicus, the ILF2 gene was characterized by bioinformatics analysis and RNAi. The sequence of 873 bp ORF region encoding 290 amino acids was obtained by PCR amplification in this study. The relative molecular weight of ILF2 protein is 32.29154 KDa. The bioinformatics analysis indicated that the ILF2 protein has an DZF domain and a RGG domain and contained a large number of alpha helices and irregular coils. The results of tissue-specific assays demonstrated that ILF2 was highly expressed in the hemolymph and gill of shrimp. After WSSV stimulation, qRT-PCR analysis showed that the expression of ILF2 was significantly increased in all tissues of shrimp. Using RNAi to knock down the expression of ILF2 in shrimp, the results showed that the copy number of WSSV in shrimp was significantly increased, suggesting that ILF2 could inhibit the replication of WSSV. The results showed that ILF2 had the potential to inhibit WSSV replication and to achieve antiviral properties, providing a theoretical basis for the control of WSSV in shrimp. [ABSTRACT FROM AUTHOR]

Background: Application of a virus-like particle (VLP) as a nanocontainer to encapsulate double stranded (ds)RNA to control viral infection in shrimp aquaculture has been extensively reported. In this study, we aimed at improving VLP's encapsulation efficiency which should lead to a superior fighting weapon with disastrous viruses. Results: We constructed 2 variants of chimeric Macrobrachium rosenbergii nodavirus (MrNV)-like particles (V1- and V2-MrN-VLPs) and tested their efficiency to encapsulate VP37 double stranded RNA as well as WSSV protection in P. vannamei. Two types of short peptides, RNA-binding domain (RBD) and deca-arginine (10R) were successfully engineered into the interior surface of VLP, the site where the contact with VP37-dsRNA occurs. TEM and dynamic light scattering (DLS) analyses revealed that the chimeric VLPs remained their assembling property to be an icosahedral symmetric particle with a diameter of about 30 nm, similar to the original MrN-VLP particle. The superior encapsulation efficiency of VP37-dsRNA into V2-MrN-VLP was achieved, which was slightly better than that of V1-MrN-VLP but far better (1.4-fold) than its parental V0-MrN-VLP which the mole ratio of 7.5–10.5 for all VLP variants. The protection effect against challenging WSSV (as gauged from the level of VP37 gene and the remaining viral copy number in shrimp) was significantly improved in both V1- and V2-MrN-VLP compared with an original V0-MrN-VLP template. Conclusion: MrN-VLP (V0-) were re-engineered interiorly with RBD (V1-) and 10R (V2-) peptides which had an improved VP37-dsRNA encapsulation capability. The protection effect against WSSV infection through shrimp administration with dsRNA + V1-/V2-MrN VLPs was experimentally evident. [ABSTRACT FROM AUTHOR]

A study was conducted to test the inclusion of Aurantiochytrium sp. meal in the rearing of Penaeus vannamei grown in a clear water system and at a suboptimal temperature of 22 °C. The doses tested were 0 (control), 1, 2, 3, and 4% at a stocking density of 100 shrimp/m3. Rearing was carried out with aeration and individual heaters, and seawater temperature was controlled with a chiller. After nine weeks, shrimp were weighed and hemolymph was collected for hemato-immunological tests, and growth performance were calculated. Shrimp raised at 22 °C and fed a 1% of dietary supplementation of Aurantiochytrium sp. meal were superior in immunological parameters. After the dietary assay, a total of 42 shrimps (10.9 ± 0.06 g) per treatment were infected with White Spot Syndrome Virus (WSSV). They were orally infected with 2.6 ± 106 virus particles per g of the animal, maintained at a suboptimal temperature of 22 °C for 108 h, and acclimated to an optimal temperature of 28 °C for an additional 48 h. At 7 days post infection, surviving shrimp were collected for hemato-immunological analysis. Cumulative mortality results showed that shrimp fed diets containing 3% and 4% Aurantiochytrium sp. meal had higher survival than other treatments when challenged with WSSV. [ABSTRACT FROM AUTHOR]

Shrimp hemocytes are the vital immune cells participating in innate immune response to defend against viruses. However, the lack of specific molecular markers for shrimp hemocyte hindered the insightful understanding of their functional clusters and differential roles in combating microbial infections. In this study, we used single-cell RNA sequencing to map the transcriptomic landscape of hemocytes from the white spot syndrome virus (WSSV)-infected Litopenaeus vannamei and conjointly analyzed with our previous published single-cell RNA sequencing technology data from the healthy hemocytes. A total of 16 transcriptionally distinct cell clusters were identified, which occupied different proportions in healthy and WSSV-infected hemocytes and exerted differential roles in antiviral immune response. Following mapping of the sequencing data to the WSSV genome, we found that all types of hemocytes could be invaded by WSSV virions, especially the cluster 8, which showed the highest transcriptional levels of WSSV genes and exhibited a cell type-specific antiviral response to the viral infection. Further evaluation of the cell clusters revealed the delicate dynamic balance between hemocyte immune response and viral infestation. Unsupervised pseudo-time analysis of hemocytes showed that the hemocytes in immune-resting state could be significantly activated upon WSSV infection and then functionally differentiated to different hemocyte subsets. Collectively, our results revealed the differential responses of shrimp hemocytes and the process of immune-functional differentiation post-WSSV infection, providing essential resource for the systematic insight into the synergistic immune response mechanism against viral infection among hemocyte subtypes. [ABSTRACT FROM AUTHOR]

Plastics in the ocean create the "plastisphere", a diverse habitat hosting various life forms. Other than the pollution induced by plastics, the co-occurrence of primary producers, symbiotic organisms, decomposers, and pathogens within the plastisphere raises questions about how they influence the dynamics of marine ecosystems. Here, we used a shotgun DNA-sequencing approach to describe the species thriving on floating plastics collected in two Mediterranean sites. Our findings revealed many species of bacteria, eukaryotes, viruses, and archaea on each plastic. Proteobacteria was dominant (70% of reads in the entire dataset), with other groups such as Ascomycota fungi (11%) and Bacteroidetes (9%) also being represented. The community structure was not affected by the polymeric composition or the plastic shape. Notably, pathogenic Vibrio species, including V. campbelli, V. alginolyticus, and V. coralliilyticus, were among the most abundant species. Viruses, despite showing lower relative abundances, occurred in all samples, especially Herpesvirales, Caudovirales, and Poxviridae groups. A significant finding was the presence of the White Spot Syndrome virus (WSSV). This pathogen, responsible for devastating outbreaks in aquaculture systems, had not been previously reported in the marine plastisphere. Our study emphasizes the need for further investigation into the ecological and economic impacts of plastisphere organisms in the ocean. [ABSTRACT FROM AUTHOR]

White spot syndrome virus (WSSV) is a highly contagious and economically costly virus that affects many crustacean species. Since its introduction into the United States in the 1990s, it has spread from aquaculture shrimp and crayfish to wild crustaceans throughout the southeastern United States. Transmission to natural systems may occur through contact between commodity (i.e. store-bought) and wild crustaceans or the use of infected frozen shrimp as bait, which has been proven capable of transmitting the virus. In this study, we surveyed both live (Penaeus setiferus (Linnaeus, 1767) and P. aztecus Ives, 1891) and frozen commodity shrimp (Penaeus vannamei Boone, 1931) and crayfish (Procambarus troglodytes (Le Conte, 1856) and P. clarkii (Girard, 1852)) as well as wild populations of some of these species of shrimp, crayfish, and blue crabs (Callinectes sapidus Rathbun, 1896) in South Carolina for WSSV. We found extremely low levels of the virus in wild-caught decapods but high levels of WSSV in commodity crayfish (50%) and imported frozen shrimp (43.3%). While additional work is needed to understand the environmental conditions that affect the transmission potential of WSSV, these results suggest that care must be taken with commodity crustaceans to prevent introductions of WSSV and subsequent harm to natural ecosystems. [ABSTRACT FROM AUTHOR]

Viral diseases are one of the constraints affecting the sustainability of the shrimp farming industry worldwide. The common causes of viral infections include white spot syndrome virus, infectious hypodermal and haematopoietic necrosis virus, hepatopancreatic parvovirus, Penaeus monodon nudivirus, decapod iridescent virus 1, Taura syndrome virus, yellow head virus, infectious myonecrosis virus and Macrobrachium rosenbergii nodavirus. Accurate diagnostic methods are necessary for preventing the spread of these transboundary diseases. Many molecular diagnostic methods for shrimp viral diseases have been developed and are currently in use, including conventional polymerase chain reaction (PCR), nested PCR, loop‐mediated isothermal amplification PCR, recombinase polymerase assay and real‐time PCR. Although the World Organization for Animal Health (founded as OIE) recommends several PCR methods for shrimp disease diagnosis, there has been a lack of efforts to comparatively evaluate the performance of the available methods, resulting in a significant knowledge gap. Therefore, in this review, we compare various PCR assays and commercial PCR‐based diagnostic kits that have been developed and/or published previously, and discuss pros and cons of each of these methods. Our objective of this review is to offer enhanced clarity and a comprehensive overview of molecular diagnostic methods for shrimp viral diseases. This endeavour would serve as an important resource for researchers engaged in relevant studies and professionals within the shrimp‐farming industry, providing valuable guidance and insights. [ABSTRACT FROM AUTHOR]

White spot disease (WSD), attributed to the white spot syndrome virus (WSSV), represents a substantial danger to the international shrimp sector, resulting in considerable losses in both production and economic terms. Nevertheless, there are currently no approved therapeutic measures to control the outbreak. This study involved the synthesis of 15 new compounds for the assessment of their anti-WSSV efficacy in Litopenaeus vannamei post-larvae. Among these compounds, N-(4-methyl-2-oxo-2H-chromen-7-yl)acetamide (P13) exhibited a maximum antiviral response of > 90 %, with a median effective concentration (EC50) < 12 mg/L, making P13 the most promising antiviral compound. In the cases where the larvae were simultaneously incubated with WSSV and P13, as well as where the larvae were first infected with WSSV and then treated with P13, the replication of WSSV was significantly inhibited. However, pre-treatment with P13 had minimal impact on WSSV multiplication, suggesting a potential therapeutic effect. Simultaneously, the cumulative mortality rate of WSSV-infected post-larvae decreased in the presence of P13. After the shrimp larvae were infected with WSSV, continuously changing the aquacultural water containing DMSO resulted in a mortality rate of 80 % at 120 hours post-infection (hpi); whereas continuously changing the aquaculture water containing P13 resulted in a mortality rate of 45 %. Given that P13 remains stable in farmed water for up to two days, it is recommended to regularly replace the medication to eliminate the virus threat. In conclusion, P13 demonstrates a positive anti-WSSV activity and holds potential for further development as an antiviral therapy against WSSV infection.

C-type lectins are known for agglutination activity and play crucial roles in regulating the prophenoloxidase (proPO) activation system, enhancing phagocytosis and encapsulation, synthesizing antimicrobial peptides, and mediating antiviral immune responses. This work cloned a C-type lectin, ladderlectin (LvLL), from Litopenaeus vannamei. LvLL comprised a 531 bp open reading frame (ORF) that encoded 176 amino acids. The predicted LvLL protein included a signal peptide and a CLECT domain. LvLL was predicted to feature a transmembrane region, suggesting it may be a transmembrane protein. LvLL was predominantly expressed in the shrimp’s hepatopancreas. After WSSV infection, LvLL expression in the hepatopancreas increased significantly by 11.35-fold after 228 h, indicating a general upregulation. Knockdown of LvLL resulted in a significant decrease in WSSV viral load and a notable increase in shrimp survival rates. Additionally, knockdown of LvLL led to a significant downregulation of apoptosis-related genes Bcl-2 and caspase 8 and a significant upregulation of p53 and proPO in WSSV-infected shrimp. This study showed that LvLL played a vital role in the interaction between L. vannamei and WSSV.

This study was conducted to determine the effect of oral administration of Zingiber officinale and Aegle marmelos extracts on the growth performance and immunomodulatory activities of the shrimp Penaeus monodon against white spot syndrome virus (WSSV). A methanol extract of the Z. officinale rhizome and A. marmelos leaf was sprayed into a pellet feed at concentrations of 0% (control), 0.05% (treatment 1), and 0.1% (treatment 2), respectively. Shrimps fed the extract (T1) showed substantial improvements in growth performance and feed utilization efficiency when compared to the control group. Extract-fed shrimp also exhibited an increase in immune-related gene expression in comparison to controls. After 4 weeks of feeding, shrimp were injected with the white spot syndrome virus and observed for another 2 weeks to determine mortality. Compared to shrimp fed the control diet, Z. officinale and A. marmelos extract–fed shrimp displayed a decrease in hemolymph clotting time and an increase in immunological parameters such as total hemocyte count, prophenoloxidase activity, and superoxide dismutase activity both before and after viral challenge. Fourteen days after the WSSV challenge, the cumulative mortality of extract-fed shrimp was considerably lower compared to the mortality of the control group which died shortly after the challenge. Therefore, the Z. officinale and A. marmelos extracts could be used as immunostimulants to enhance the growth and resistance of shrimp against the white spot syndrome virus. [ABSTRACT FROM AUTHOR]

Simple Summary: Five feed protein levels (32%, 36%, 40%, 44%, and 48%) were set up using fishmeal as the sole protein source to study the effects of different feed protein levels on the intestinal microbiota and transcriptome responses of L. vannamei. It was found that the optimal feed protein level for shrimp L. vannamei is between 40% and 44%. Excessively high or low feed protein levels reduce antioxidant levels and digestive enzyme activity and promote pathogen colonization. The transcriptional regulation of inappropriate protein levels responds to the body by reducing factors in various metabolic pathways. The weakened genes impede metabolic processes and compromise immunological function, increasing the organism's vulnerability to diseases. This can impair the immune systems of shrimp and cause stunted growth. This study explored the effects of dietary protein levels on Litopenaeus vannamei with its intestinal microbiota and transcriptome responses. Previous studies on the effects of dietary protein levels on L. vannamei have focused on growth performance, antioxidant indices, and digestive enzyme activity, but few studies have been conducted at the microbiological and molecular levels. In this study, five isolipid experimental diets with protein levels of 32% (P32), 36% (P36), 40% (P40), 44% (P44), and 48% (P48) were used in an L. vannamei (0.63 ± 0.02 g) feeding trial for 56 days. At the end of the feeding trial, the growth performance, immunity, intestinal health, and transcriptional responses of L. vannamei were determined. This study demonstrated that higher protein levels (P44) led to superior weight gain and growth rates for L. vannamei, with lower feed conversion ratios (FCR) observed in the P48 and P44 groups compared to the P32 and P36 groups (p ≤ 0.05). The P44 and P48 groups also showed a notably higher protein efficiency ratio (PER) compared to others (p ≤ 0.05), and there was no significant difference between them. Upon Vibrio parahaemolyticus infection, the P48 group exhibited a significantly lower survival rate (SR) within 48 h, while during 72 h of white spot syndrome virus (WSSV) infection, the P44 group had a notably higher survival rate than the P32 group (p ≤ 0.05). Digestive enzyme activity and antioxidant levels in L. vannamei initially increased and then decreased as protein levels increased, usually peaking in the P40 or P44 groups. Lower dietary protein levels significantly reduced the relative abundance of beneficial bacteria and increased the relative abundance of pathogenic bacteria in the intestines of L. vannamei. Transcriptome sequencing analysis revealed that most differentially expressed genes (DEGs) were up-regulated and then down-regulated as dietary protein levels increased. Furthermore, KEGG pathway enrichment analysis indicated that several immune and metabolic pathways, including metabolic pathways, glutathione metabolism, cytochrome P450, and lysosome and pancreatic secretion, were significantly enriched. In summary, the optimal feed protein level for L. vannamei shrimp was 40–44%. Inappropriate feed protein levels reduced antioxidant levels and digestive enzyme activity and promoted pathogen settlement, deceasing factors in various metabolic pathways that respond to microorganisms through transcriptional regulation. This could lead to stunted growth in L. vannamei and compromise their immune function. [ABSTRACT FROM AUTHOR]

This article discusses the detection and confirmation of White Spot Syndrome Virus (WSSV) in crayfish in Alabama. The virus was detected using quantitative PCR (qPCR) and confirmed through whole genome sequencing. The genome sequence of the WSSV isolate from Alabama was found to be similar to shrimp and prawn isolates from China and Australia. The study suggests that further research is needed to understand the transmission and prevalence of WSSV in crayfish populations. The data from this study is available upon request from the corresponding author. [Extracted from the article]

Autophagy generally functions as a cellular surveillance mechanism to combat invading viruses, but viruses have evolved various strategies to block autophagic degradation and even subvert it to promote viral propagation. White spot syndrome virus (WSSV) is the most highly pathogenic crustacean virus, but little is currently known about whether crustacean viruses such as WSSV can subvert autophagic degradation for escape. Here, we show that even though WSSV proliferation triggers the accumulation of autophagosomes, autophagic degradation is blocked in the crustacean species red claw crayfish. Interestingly, the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex including CqSNAP29, CqVAMP7, and the novel autophagosome SNARE protein CqSyx12 is required for autophagic flux to restrict WSSV replication, as revealed by gene silencing experiments. Simultaneously, the expressed WSSV tegument protein VP26, which likely localizes on autophagic membrane mediated by its transmembrane region, binds the Qb-SNARE domain of CqSNAP29 to competitively inhibit the binding of CqSyx12-Qa-SNARE with CqSNAP29-Qb-SNARE; this in turn disrupts the assembly of the CqSyx12-SNAP29-VAMP7 SNARE complex, which is indispensable for the proposed fusion of autophagosomes and lysosomes. Consequently, the autophagic degradation of WSSV is likely suppressed by the expressed VP26 protein in vivo in crayfish, thus probably protecting WSSV components from degradation via the autophagosome-lysosome pathway, resulting in evasion by WSSV. Collectively, these findings highlight how a DNA virus can subvert autophagic degradation by impairing the assembly of the SNARE complex to achieve evasion, paving the way for understanding host-DNA virus interactions from an evolutionary point of view, from crustaceans to mammals. IMPORTANCE White spot syndrome virus (WSSV) is one of the largest animal DNA viruses in terms of its genome size and has caused huge economic losses in the farming of crustaceans such as shrimp and crayfish. Detailed knowledge of WSSV-host interactions is still lacking, particularly regarding viral escape from host immune clearance. Intriguingly, we found that the presence of WSSV-VP26 might inhibit the autophagic degradation of WSSV in vivo in the crustacean species red claw crayfish. Importantly, this study is the first to show that viral protein VP26 functions as a core factor to benefit WSSV escape by disrupting the assembly of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex, which is necessary for the proposed fusion of autophagosomes with lysosomes for subsequent degradation. These findings highlight a novel mechanism of DNA virus evasion by blocking SNARE complex assembly and identify viral VP26 as a key candidate for anti-WSSV targeting. [ABSTRACT FROM AUTHOR]

In this study, Pacific white shrimp (Penaeus vannamei), pond water, crab, Helice tridens, and live food samples were collected from farms in three provinces of Korea to investigate the presence of white spot syndrome virus (WSSV) and decapod hepanhamaparvovirus (DHPV). By polymerase chain reaction (PCR), DHPV was detected in all shrimp samples (83 of 83); among these, 41 samples were detected with WSSV. Amplicon sequencing and phylogenetic analyses indicated that all DHPV samples were classified as a novel genotype of DHPV. Additionally, the collected squid, polychaeta, and crab were also confirmed to be detected with novel genotypes of DHPV. By WSSV quantitative PCR, the average concentrations of viruses detected in shrimp and pond water samples were 2.58 × 107 copies/μL and 1.27 × 102 copies/μL, respectively. Simultaneous detection of WSSV and DHPV was observed in shrimp, pond water, and crab samples, and co‐infection with both viruses in shrimp could be demonstrated by histopathological analysis. Viral infection can result in significant economic losses in shrimp production. Therefore, precise monitoring and management of WSSV and DHPV prevalence in pond water, live food, and habitats are essential to preventing the spread of viral diseases in the Korean shrimp culture industry. [ABSTRACT FROM AUTHOR]

In this study, the primers of different protocols for the detection of White Spot Syndrome Virus (WSSV) were analyzed in silico to evaluate their potential performance in PCR. As with any biological entity, this virus evolves constantly. Thus, this analysis showed that a few primers, including those recommended by the World Organization for Animal Health (WOAH), might mismatch with some isolates of WSSV, specially with isolates more recently sequenced. Furthermore, a set of primers recommended by WOAH, showed the potential to self-dimer and form hairpin loop structures, which could affect the efficiency of PCR, resulting in an inaccurate diagnostic result. From our perspective, and considering the evolutionary trajectory of this virus, it may be time for the WOAH to update the PCR protocols recommended for WSSV detection, which remains as a highly prevalent and lethal virus. [ABSTRACT FROM AUTHOR]

Simple Summary: Diseases pose a significant challenge for aquaculture, exacerbated by changing weather conditions. The sector has explored various strategies, including maintaining a clean environment and employing vaccines, to combat these diseases. However, these solutions are effective only against specific diseases and species. In our recent research, we investigated the use of genetics to enhance disease resistance in three crucial species: white leg shrimp, striped catfish, and yellowtail kingfish. Our findings indicate that the studied populations of these species possess genes that can be inherited, imparting greater resistance to diseases such as White Spot Syndrome Virus, Bacterial Necrotic Pancreatitis, and skin fluke. By selectively breeding animals with these resistant genes, we successfully increased resistance within the population, promoting overall fish health and boosting production. Additionally, we examined these genes and utilized computer models to predict the most resistant individuals for breeding to combat diseases. Looking ahead, our focus is on omics technologies, precision farming systems, and advanced algorithms to further enhance the disease resistance of these species, thereby making aquaculture more sustainable and resilient against threats. Diseases pose a significant and pressing concern for the sustainable development of the aquaculture sector, particularly as their impact continues to grow due to climatic shifts such as rising water temperatures. While various approaches, ranging from biosecurity measures to vaccines, have been devised to combat infectious diseases, their efficacy is disease and species specific and contingent upon a multitude of factors. The fields of genetics and genomics offer effective tools to control and prevent disease outbreaks in aquatic animal species. In this study, we present the key findings from our recent research, focusing on the genetic resistance to three specific diseases: White Spot Syndrome Virus (WSSV) in white shrimp, Bacterial Necrotic Pancreatitis (BNP) in striped catfish, and skin fluke (a parasitic ailment) in yellowtail kingfish. Our investigations reveal that all three species possess substantial heritable genetic components for disease-resistant traits, indicating their potential responsiveness to artificial selection in genetic improvement programs tailored to combat these diseases. Also, we observed a high genetic association between disease traits and survival rates. Through selective breeding aimed at enhancing resistance to these pathogens, we achieved substantial genetic gains, averaging 10% per generation. These selection programs also contributed positively to the overall production performance and productivity of these species. Although the effects of selection on immunological traits or immune responses were not significant in white shrimp, they yielded favorable results in striped catfish. Furthermore, our genomic analyses, including shallow genome sequencing of pedigreed populations, enriched our understanding of the genomic architecture underlying disease resistance traits. These traits are primarily governed by a polygenic nature, with numerous genes or genetic variants, each with small effects. Leveraging a range of advanced statistical methods, from mixed models to machine and deep learning, we developed prediction models that demonstrated moderate-to-high levels of accuracy in forecasting these disease-related traits. In addition to genomics, our RNA-seq experiments identified several genes that undergo upregulation in response to infection or viral loads within the populations. Preliminary microbiome data, while offering limited predictive accuracy for disease traits in one of our studied species, underscore the potential for combining such data with genome sequence information to enhance predictive power for disease traits in our populations. Lastly, this paper briefly discusses the roles of precision agriculture systems and AI algorithms and outlines the path for future research to expedite the development of disease-resistant genetic lines tailored to our target species. In conclusion, our study underscores the critical role of genetics and genomics in fortifying the aquaculture sector against the threats posed by diseases, paving the way for more sustainable and resilient aquaculture development. [ABSTRACT FROM AUTHOR]

The white spot syndrome virus (WSSV) is a highly lethal pathogen for several crustacean species, which implies that this virus has caused high mortalities and significant economic losses for the global shrimp aquaculture industry. Viruses' entry into the host cell depends on the interaction between those proteins located on the surface of the virus and its attachment to specific surface-exposed cell receptors. In this review, the findings in the interaction of the receptors recognized by WSSV proteins are summarized and discussed, providing thus a comprehensive and finer understanding of the importance of these molecules for WSSV pathogenesis, as well as suggesting strategies targeting critical components for the design and development of therapeutic antivirals against WSSV that could be used in shrimp farming. [ABSTRACT FROM AUTHOR]

Three molecular assays were used to detect and quantify white spot syndrome virus (WSSV) in DNA extracted from seston size-fractioned (0.02, 0.2, 1.2, and 20 µm) samples collected from a coastal lagoon and an adjacent shrimp farm. From 107 DNA extracts, only two from one sample tested positive for WSSV with nested PCR in the 1.2 and 20 µm fractions. These results were confirmed by a semi-quantitative (IQ2000TM WSSV Detection and Prevention System) and a quantitative (IQREALTM WSSV Quantitative System) detection system based, based, respectively, on nested PCR and real-time PCR. A first viral load reference value (6.54 × 104 WSSV copies/mL) was established in a seston size fraction (1.2-20 µm). The results suggest that WSSV could be associated with both resuspension of fine clays and silts, and nanoplankton and organic colloids during infectious events. [ABSTRACT FROM AUTHOR]

Recently, the spread of white spot disease in shrimps has a major impact on the aquaculture activity worldwide affecting the economy of the countries, especially South-East Asian countries like Vietnam. This deadly disease in shrimps is caused by the White Spot Syndrome Virus (WSSV). Researchers are trying to understand the spread and control of this disease by doing field and laboratory studies considering effect of environmental conditions on shrimps affected by WSSV. Generally, they have not considered spatial factors in their study. Therefore, in the present study, we have used spatial (distances to roads and factories) as well as physio-chemical factors of water: Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Salinity, NO3, P3O4 and pH, for developing WSSV susceptibility maps of the area using Decision Tree (DT)-based Machine Learning (ML) models namely Random Tree (RT), Extra Tree (ET), and J48. Model's performance was evaluated using standard statistical measures including Area Under the Curve (AUC). The results indicated that ET model has the highest accuracy (AUC: 0.713) in predicting disease susceptibility in comparison to other two models (RT: 0.701 and J48: 0.641). The WSSV susceptibility maps developed by the ML technique, using DT (ET) method, will help decision makers in better planning and control of spatial spread of WSSV disease in shrimps. [ABSTRACT FROM AUTHOR]

Purpose: Although shrimp aquaculture in Sri Lanka has mainly been plagued by recurrent outbreaks of White Spot Syndrome Virus (WSSV), recent symptomatic and analytical field data of shrimps were incoherent with typical WSSV infections. As transboundary infection of new diseases is not uncommon in world shrimp aquaculture, the possibility of new diseases established in the country surfaced. Hence, the present study was aimed at evaluating the stock health of shrimps in Sri Lanka for additional six diseases commonly available in the Asian region, namely Infectious Hypodermal and Hematopoietic Necrosis Virus (IHHNV), Infectious Myonecrosis Virus (IMNV), Taura Syndrome Virus (TSV), Yellow Head Virus (YHV), Acute Hepatopancreatic Necrosis (AHPND) and Necrotizing Hepatopancreatitis Bacterium (NHPB). Research Method: Sampling was performed using broodstocks, postlarvae, cultured Penaeus monodon, wild P. semisulcatus, P. indicus and P. monodon from different locations and broodstock collecting areas in the country. Other crustacean species were also collected as possible carrier species. The presence of pathogenic organisms was identified by Polymerase Chain Reaction using respective IQ 2000TM test kits and a total of 2060 PCR tests were conducted. Findings: Of all the samples tested, no samples were positive for IMNV, TSV, YHV, AHPND and NHPB. However, confirmatory evidence was found in Sri Lanka for the presence of IHHNV with the prevalence of 31.3% in broodstock samples, 24.07% in hatchery-produced postlarvae and 18.03% in cultured shrimps. WSSV was also recorded with a prevalence of 10.34% in broodstock samples and 55.56% in cultured shrimp samples collected. None of the wild collected samples was positive for any of the tested diseases. Originality/value: Reinstating the presence of WSSV in the Sri Lankan shrimp industry, provides confirmatory evidence of the presence of IHHNV in the country, highlighting the possibility of the emergence of new diseases in shrimp farming in Sri Lanka. Also, commonly suggested disease carriers seem to be not the major cause of disease spread during the sampling time. This study, therefore, provides much-needed information about the stock health of shrimps in Sri Lanka. [ABSTRACT FROM AUTHOR]