Shrimp Disease Research Articles

Effect of bacteriophage on histopathology and disease resistance of Whiteleg shrimp (Litopenaeus vannamei) infected by Vibrio parahaemolyticus

Vibrio parahaemolyticus is the causative agent of shrimp diseases, the most serious of which is acute hepatopancreatic necrosis disease (AHPND). Bacteriophage is a virus of bacteria that can parasitize and destroy bacteria, so it is considered a potential alternative to antibiotics. The study was carried out to evaluate the treatment ability of bacteriophages on Litopenaeus vannamei after being infected by V. parahaemolyticus B4XOT2.2 isolated from the bottom mud of shrimp ponds infected with AHPND. The study used the histopathological survey method on shrimp at all three ages: postlarvae, adult shrimp at the ages of 30–45 days, and 55–60 days old, which were arranged into three treatments: healthy shrimp, diseased shrimp, and bacteriophage-treated shrimp. The results showed that: the concentration of Vibrio spp. in bacteriophage-treated treatment was decreased in all three groups (postlarvae, shrimp at the ages of 30–45 days, and 55–60 days old) from 3,7x103 CFU/mL to 2,2x102 CFU/mL after two days, from 4,6x104 CFU/mL to 3,3x102 CFU/mL after two days and from 4,6x104 CFU/mL to 5,6x103 CFU/mL after three days, respectively. The pathological signs and histological features of the infected shrimp samples were similar to those typical of acute hepatopancreatic necrosis disease and recovered in shrimp tissue after being treated with bacteriophages such as the hepatopancreas was also darker, the intestines gradually filled, no hematoma around the tubules were found, in the lumen of the tube reduced sloughing cells and blood cells, no melanization was observed.

An Overview of the Biological Functions and Mechanisms of Action of Medicinal Plants and Seaweeds in the Shrimp Culture.

Diseases are major constraints to developing large-scale aquaculture practices in many countries. For decades, synthetic chemotherapeutic agents have been widely applied both as prophylactics and therapeutics to inhibit and control aquatic disease outbreaks. However, their use has become more restricted due to the negative impacts they have on the environment, the host and humans, as well as their limitations in preventing the emergence of antimicrobial-resistant bacteria. Therefore, there is a growing interest in the use of medicinal plants and seaweeds as potential alternatives to antibiotics and other synthetic chemotherapeutics. Medicinal plants and seaweeds can enhance the immune systems of animals, thereby providing protection against numerous diseases while minimizing the adverse effects associated with synthetic chemotherapeutics. Furthermore, the advantages of medicinal plants and seaweeds, such as their effectiveness, easy availability and ability to be applied on a large scale, make them appealing for use in the aquaculture industry. The main goal of this study was to review the existing knowledge of the effects of medicinal plants and seaweeds, as well as their extracts, on shrimp growth, immune response and disease resistance against bacterial and viral agents. Moreover, this paper discusses the application of seaweeds in shrimp culture. We also conducted a literature review to identify gaps in the research and provide recommendations for further advancement in this field of study. Further studies should focus on evaluating other physiological aspects, such as feed and mineral utilization, enzyme activities and histological examination.

PirA- or PirB-binding nanobodies can protect whiteleg shrimp from the acute hepatopancreatic necrosis disease toxin.

Acute hepatopancreatic necrosis disease (AHPND) is a devastating shrimp disease caused by a binary toxin, PirAB, produced by Vibrio parahaemolyticus and other closely related bacteria. To address AHPND, over 300 unique single-domain antibodies (also known as nanobodies) derived from the VHH domains of Lama glama heavy-chain-only antibodies were raised against either PirA or PirB and characterized. Nanobodies were shortlisted based on their affinities for either PirA or PirB, their relative stability in intestinal fluids, and their ability to reduce PirAB-induced death in brine shrimp Artemia salina. From these data, a subset of nanobodies was tested for their ability to reduce AHPND in whiteleg shrimp Penaeus vannamei, and nanobodies targeting either PirA or PirB provided significant disease protection to whiteleg shrimp. These results show that nanobodies can be a new option for shrimp farmers to reduce or eliminate the impact of AHPND on their operations.

Microbes and pathogens associated with shrimps - implications and review of possible control strategies

Shrimp aquaculture has been growing rapidly over the last three decades. However, high-density aquaculture together with environmental degradation has led to increased incidence of shrimp infections. Thus, devising and implementing effective strategies to predict, diagnose and control the spread of infections of shrimps are crucial, also to ensure biosecurity and sustainability of the food industry. With the recent advancements in biotechnology, more attention has been given to develop novel promising therapeutic tools with potential to prevent disease occurrence and better manage shrimp health. Furthermore, owing to the advent of the next-generation sequencing (NGS) platforms, it has become possible to analyze the genetic basis of susceptibility or resistance of different stocks of shrimps to infections and how sustainable aquaculture could be made free of shrimp diseases.

Passive immunoprophylaxis with Ccombodies against Vibrio parahaemolyticus in Pacific white shrimp (Penaeus vannamei)

The Vibrio parahaemolyticus strain causing acute hepatopancreatic necrosis disease (AHPND) in shrimp secretes toxins A and B (PirAVp/PirBVp). These toxins have been implicated in pathogenesis and are targets for developing anti-AHPND therapeutics or prophylactics that include passive immunization. We have previously reported that Ccombodies (recombinant hagfish variable lymphocyte receptor B antibodies; VLRB) targeting PirBVp conferred protection against V. parahaemolyticus in shrimp when administered as a feed supplement. In this study, we screened a phage-displayed library of engineered VLRBs for PirAVp-targeting Ccombodies that were mass-produced in a bacterial expression system. We then introduced these Ccombodies into the diet of Pacific white shrimp (Penaeus vannamei) over a seven-day period. Subsequently, the shrimp were exposed to a challenge with V. parahaemolyticus. Mortality rates were then observed and recorded over the following seven days. Administering shrimp feed supplemented with Ccombodies at a high dose (100 mg per 100 g feed) reduced mortality in recipient animals (2.96-5.19%) statistically similar to mock-challenged control (1.48%), but significantly different from the Ccombody-deficient control (74.81%). This suggests that the Ccombodies provided strong protection against the bacterium. Feeding shrimp with a median dose (10 mg/100 g feed) gave statistically comparable low mortality (5.93-6.67%) as the high dose. Reducing the Ccombody dose to 1 mg/100 g feed showed variable effects. Ccombody A2 showed mortality (11.85%) significantly lower than that of the Ccombody-deficient group (74.81%), suggesting that it can effectively protect against the bacterial challenge at a low dose. Our results demonstrate the ability of the phage-displayed VLRB library to generate antigen-specific Ccombodies rapidly and simply, with the expression of high protein levels in bacteria. The protective effect provided by these Ccombodies aligns with our earlier results, strongly supporting the use of VLRB antibodies as a substitute for IgY in passive immunoprophylaxis against AHPND in shrimp.

Assessing White Spot Syndrome Virus (WSSV) and Acute Hepatopancreatic Necrosis Disease (AHPND) concurrent with Vibrio spp. in various Penaeus monodon aquaculture farms at southwestern region of Bangladesh

This study was conducted to assess the prevalence of White Spot Syndrome Virus (WSSV) and Acute Hepatopancreatic Necrosis Disease (AHPND) in giant tiger shrimp (Penaeus monodon Fabricius, 1798) aquaculture systems (extensive, improved-extensive, and semi-intensive) in the south-western region of Bangladesh. This research employed real-time polymerase chain reaction (RT-PCR) to quantification cycle (Cq) values for identification of WSSV and AHPND in shrimp samples and Vibrio spp. was identified through biochemical tests on water and soil samples (n=72 for each) from different aquaculture systems. The results of the study indicated significant difference (p < 0.05) in nitrate and ammonia levels across the various aquaculture systems, highlighting the critical need for rigorous water quality monitoring and management. Extensive aquaculture exhibited the highest prevalence of WSSV (40%) and AHPND (33%) positive samples, whereas semi-intensive aquaculture had the lowest prevalence, with 22% WSSV-positive and 20% AHPND-positive samples. Biochemical analysis identified three Vibrio spp. such as V. cholerae, V. vulnificus, and V. parahaemolyticus - with significantly higher concentrations in extensive aquaculture compared to semi-intensive. Notably, V. vulnificus was more abundant (0.9×103 cfu/ml) in the soil of extensive aquaculture, while it was less prevalent in water. In conclusion, this study underscores that the risk of WSSV and AHPND was greater in extensive aquaculture due to inadequate management.

The 2023 National Proficiency Test for molecular detection of shrimp infectious myonecrosis virus (IMNV) in China

Infectious myonecrosis virus (IMNV), an emerging virus that can cause severe viral disease in penaeid shrimp, was first confirmed to have spread to China in 2020. In order to standardize diagnostic procedures and reliable detection capability, and to evaluate the performances of aquatic clinical diagnostic laboratories, the competent authority has launched a proficiency test (PT) scheme for the molecular detection of IMNV in China from the year of 2023. In the ring test of IMNV-PT 2023, five tissue samples containing different concentrations of IMNV were provided as a panel of test samples. A total of 68 laboratories participated in the PT test of qualitative and quantitative analysis of the five samples using standard molecular assays. The results showed that 92.65 % (63/68) of the participants correctly reported all samples in the panel using Real-time reverse transcription PCR and 62 participants achieved satisfactory results, one participant using conventional PCR and four participants had not completed the test. Out of the 62 participants in the z-scores analysis, 88.71 % (55/62) achieved acceptable ZB-scores, with two outlier laboratories and five laboratories being questionable. Additionally, 98.39 % (61/62) achieved ZW-scores, with only one laboratory being questionable. Furthermore, the national PT conducted in the present study proved to be an effective tool for evaluating laboratory performance in IMNV molecular testing. This assessment can aid in improving the capabilities of IMNV molecular testing of the participating laboratories, and also provided technical supporting to enhance the national response to IMN outbreaks.

Immunofluorescence detection of Ecytonucleospora hepatopenaei (EHP) in Penaeus vannamei

Hepatopancreatic microsporidiosis (HPM), caused by the microsporidium Ecytonucleospora hepatopenaei (EHP) leads to retarded growth and enhanced susceptibility to other diseases in shrimp resulting in a major loss for the shrimp industry worldwide. It is little understood how EHP infects its host and hijacks its cellular machinery to replicate and exert clinical manifestations in infected shrimp. Since the initial record of HPM, histopathology and polymerase chain reaction (PCR)-based assays were developed for the detection of EHP to prevent spread of the disease. Availability of an antibody-based detection method would complement these existing diagnostic tools and be useful in studying EHP pathogenesis. We describe here an immunofluorescence assay (IFA) for detecting EHP using monoclonal antibodies (mAbs) that were originally developed against Cryptosporidium parvum, a coccidian parasite that infects calves (Bos taurus), other agriculturally important animals, and humans. Forty-one mAbs were screened and two mAbs, 3E2 and 3A12, were found to detect EHP successfully. The utility of these mAbs in detecting EHP was further assessed by testing 36 experimentally challenged EHP-infected shrimp (Penaeus vannamei). EHP-detection data from infected shrimp were compared by Hematoxylin and Eosin (H&E) histology, real-time PCR, and immunofluorescence. The data show IFA using mAbs 3E2 and 3A12 could successfully detect EHP and that the sensitivity of detection is comparable to H&E histology and quantitative PCR. Availability of mAbs that can detect EHP is expected to be immensely beneficial in HPM diagnosis. Since the pathobiology of C. parvum has been so widely studied, these cross-reactive mAbs may also aid in gaining some insight into EHP pathogenesis and disease.

Biological and genomic characterization of the novel bacteriophage vB_VpM-pA2SJ1, which infects Vibrio parahaemolyticus associated with acute hepatopancreatic necrosis disease.

Vibrio parahaemolyticus is a major seafood-borne zoonotic pathogen that causes gastroenteritis in humans and acute hepatopancreatic necrosis disease (AHPND) in shrimp. In this study, we isolated and characterized Vibrio phage vB_VpM-pA2SJ1, which infects clinical and AHPND-associated strains of V. parahaemolyticus. The phage genome is a linear dsDNA 51,054 bp in length with a G + C content of 43.7%, and it contains 89 open reading frames. Genome comparisons revealed basal similarity to other Vibrio phages, particularly Vibrio phage vB_VpP_1, with 84.2% identity and 46% coverage. Phylogenetic analysis based on the whole genome, the terminase large subunit, and the major capsid protein revealed that phage vB_VpM-pA2SJ1 did not cluster with other known phage families, thus indicating its uniqueness.

Bile acids activate the antibacterial T6SS1 in the gut pathogen Vibrio parahaemolyticus.

The marine bacterium Vibrio parahaemolyticus is a major cause of seafood-borne gastroenteritis in humans and of acute hepatopancreatic necrosis disease in shrimp. Bile acids, produced by the host and modified into secondary bile acids by commensal bacteria in the gastrointestinal tract, induce the virulence factors leading to disease in humans and shrimp. Here, we show that secondary bile acids also activate this pathogen's type VI secretion system 1, a toxin delivery apparatus mediating interbacterial competition. This finding implies that Vibrio parahaemolyticus exploits secondary bile acids to activate its virulence factors and identify the presence of commensal bacteria that it needs to outcompete in order to colonize the host.IMPORTANCEBacterial pathogens often manipulate their host and cause disease by secreting toxic proteins. However, to successfully colonize a host, they must also remove commensal bacteria that reside in it and may compete with them over resources. Here, we find that the same host-derived molecules that activate the secreted virulence toxins in a gut bacterial pathogen, Vibrio parahaemolyticus, also activate an antibacterial toxin delivery system that targets such commensal bacteria. These findings suggest that a pathogen can use one cue to launch a coordinated, trans-kingdom attack that enables it to colonize a host.

In silico identification and functional study of long non-coding RNA involved in acute hepatopancreatic necrosis disease caused by Vibrio parahaemolyticus infection in white shrimp, Litopenaeus vannamei

Acute hepatopancreatic necrosis disease (AHPND) caused by toxin-producing Vibrio parahaemolyticus (VpAHPND) has severely affected shrimp production. Long non-coding RNA (lncRNA), a regulatory non-coding RNA, which can play important function in shrimp disease responses. This study aimed to identify and investigate the role of lncRNA involved in VpAHPND infection in Pacific white shrimp, Litopenaeus vannamei. From a total of 368,736 de novo assembled transcripts, 67,559 were identified as putative lncRNAs, and only 72 putative lncRNAs showed differential expression between VpAHPND-infected and normal shrimp. The six candidate lncRNAs were validated for their expression profiles during VpAHPND infection and tissue distribution using RT-qPCR. The role of lnc2088 in response to VpAHPND infection was investigated through RNA interference. The result indicated that the suppression of lnc2088 expression led to an increase in shrimp mortality after VpAHPND infection. To explore the set of genes involved in lnc2088 knockdown, RNA sequencing was performed. A total of 275 differentially expressed transcripts were identified in the hepatopancreas of lnc2088 knockdown shrimp. The expression profiles of five candidate metabolic and immune-related genes were validated in lnc2088 knockdown and VpAHPND-infected shrimp. The result showed that the expression of ChiNAG was significantly increased, while that of NCBP1, WIPF2, and NFKB1 was significantly downregulated in ds2088-injected shrimp. Additionally, the expression of NFKB1, NCBP1 and WIPF2 was significantly increased, whereas that of ChiNAG and CUL5 were significantly decreased after infection with VpAHPND. Our work identified putative lncRNA profiles in L. vannamei in response to VpAHPND infection and investigated the role of lncRNA in shrimp immunity.

Polyculture of Genetically Improved Farmed Tilapia (GIF tilapia) and Penaeus vannamei Using Biofloc Technology – A Review

According to Food and Agriculture Organization of the United Nations (FAO), aquaculture has grown faster and its expansion aimed at meeting the increase of world fish demand, and preserving natural fish stocks. Currently, to produce fish in quantity and quality requires reduction of the environmental impact from aquaculture, through the improvement of culture systems. Disease is the major factor affecting the development and expansion in aquaculture. Losses due to disease in shrimp farming are high. Various approaches to minimize the impact of disease on production are possible. Another approach to keep the pathogen pressure low is polyculture of shrimp and finfish. This practice makes shrimp farming more sustainable by reducing the environmental impact and the incidence of shrimp disease. Antimicrobial peptides in the fish skin kill shrimp pathogens, keeping pathogen pressure of bacteria and viruses low. In polyculture, shrimps can eat tilapia faeces and unused fish feed, while tilapia filter phytoplankton, reducing the risk of low dissolved oxygen levels at night. In addition, shrimp bioturbation at the pond bottom returns nutrients to the water column, enhancing phytoplankton production and consequently the natural feed available for the tilapia. Biofloc technology (BFT) is one of the most applicable and promising systems for sustainable aquaculture development. This technology is essentially based on the recycling of nutrients via microorganisms, primarily (i) heterotrophic bacteria, which convert nitrogen compounds into microbial biomass, in addition to serves as a source of food for aquatic organisms, and (ii) chemoautotrophic bacteria, which convert ammonia to nitrite and nitrate.

First report of white muscle disease caused by Photobacterium damselae subsp. damselae in Kuruma shrimp (Penaeus japonicus)

In August and September 2022, two disease outbreaks were observed in Kuruma shrimp (Penaeus japonicus) farms in Okinawa, Japan. Diseased animals exhibited clinical signs of whitened musculature extending from the abdominal to the distal region. Histopathology revealed degeneration of fibers due to liquified muscle necrosis and haemocytic infiltration. Analysis of nonhost contigs from the assembled unmapped RNA and DNA shotgun sequence reads showed significant taxonomic alignment to bacterial species. This led to the investigation of a bacterium as a possible causative agent by characterizing its population in the diseased shrimp muscle. The majority of the 16S rRNA sequence recombinant clones had their highest homology with Photobacterium sp. (> 99%). The three bacterial isolates from the whitened muscle tissue were identified as Photobacterium damselae subsp. damselae (WMD-P1, WMD-P2 and WMD-P3) by biochemical and molecular assays and were further characterized. The Pdd genomes consisted of two circular chromosomes with varying numbers of plasmid. Its size ranges from 4.47 Mb to 4.60 Mb with an average GC content of 40.8%, with predicted number of coding sequences (CDs) ranging from 3816 to 4031. hlyA and pldA genes encoding for leukocidin pore-forming toxin and phospholipase were identified. Putative virulence genes are involved in adherence, antiphagocytosis, chemotaxis and motility, iron uptake, quorum sensing, secretion system, and immune evasion. The presence of prophages, genomic islands and antimicrobial resistant genes in the Pdd genomes suggests episodes of horizontal gene transfer. Average nucleotide identity (ANI) and pangenome analyses revealed a high genetic relationship of the Pdd strains (>98%) to isolates from other sources. PCR assays validated the presence of two bacterial virulence genes encoding the pore-forming toxin and phospholipase respectively in all isolates. Also, the strains had chitinase, phospholipase, and hemolytic activities. Intramuscular injection at 1 × 108 CFU/ml bacterial concentration produced pathological signs similar to those in naturally infected shrimp after 24 hpi. Lower concentration of 1 × 103 CFU/ml resulted in morbidity after 10 dpi. These results show that P. damselae subsp. damselae (Pdd) is associated with the occurrence of white muscle disease in Kuruma shrimp.

Real-time triplex loop-mediated isothermal amplification (LAMP) using a turbidimeter for detection of shrimp infectious hypodermal and hematopoietic necrosis virus (IHHNV).

The World Organization for Animal Health still regulates the infectious hypodermal and hematopoietic necrosis virus (IHHNV) in shrimp. The existing disease identification approach is time consuming, necessitates expensive equipment, and requires specialized expertise, thereby limiting the accessibility of shrimp disease screening on farms. Loop-mediated isothermal amplification (LAMP) is recognized for its ability to detect inhibitory substances with high sensitivity and specificity. We developed a real-time triplex LAMP assay that combines the simplicity of point-of-care testing with the accuracy of a turbidimeter. Using a set of three LAMP primers, our technology enables rapid DNA amplification in a single reaction within 45 min and with a low detection limit (10 copies/reaction). We tested 192 shrimp samples from different sources and demonstrated the clinical utility of our method, achieving 100% specificity (95% confidence interval = 93.40-100.00%), 100% sensitivity (97.36-100.00%), and 100% accuracy (98.10-100.00%) in detecting IHHNV DNA, with a high Cohen's kappa value (1) compared to the standard quantitative polymerase chain reaction assay. The high technology readiness level of our method makes it a versatile platform for any real-time LAMP assay, and its low cost and simplicity make it well suited for fast deployment and use in shrimp farming.

Identification and Molecular Analysis of Hemocyanin as a Body Resistance Gene in Litopenaeus vannamei

Production of white shrimp (Litopenaeus vannamei) tends to decrease every year caused by diseases, one of which is White Feces Disease (WFD). Genetically, monitoring has been carried out on the parent characters of SPF (Specific Pathogen Free) shrimp imported from Hawaii and Florida with low genetic variation. If there is a threat such as disease caused by bacteria and the gene that codes for disease control or the body's resistance gene is missing, it allows the individual to become susceptible to disease. Gene that codes for body resistance in white shrimp is hemocyanin. Hemocyanin gene studies are needed as a first step in controlling disease in white shrimp. Method used is a descriptive method. Procedures carried out are sample collection, detection of WFD, molecular analysis of hemocyanin and data analysis. Results showed that healthy shrimp had hemocyanin while shrimp with WFD had very little or no amount of hemocyanin. Hemocyanin gene profile in healthy shrimp was also analyzed and there were 4 nucleotide change made changes to 4 amino acid. Changes in amino acids affect the stability of hemocyanin and cause polymorphism of hemocyanin. Phylogenetic analysis showed dendogram split into two clades between L. vannamei and P. monodon.

Pharmacokinetics and Withdrawal Times of Cefotaxime in White Leg Shrimp (Litopenaeus vannamei) after Oral Administration

A high-performance liquid chromatography method coupled to tandem mass spectrometry was validated in order to study the pharmacokinetics of cefotaxime in shrimp hepatopancreases and plasma, as well as its withdrawal time related to a maximum residue limit (MRL) in shrimp muscle. Pharmacokinetics parameters were investigated through oral medication at a single dose of 25 mg/kg shrimp body weight and subsequent hepatopancreas and plasma cefotaxime concentration measurements at 0.5, 1, 2, 4, 8, 12 and 24 h after shrimp were fed with medication. The maximum concentration of cefotaxime was observed after one hour in the hepatopancreas (Cmax, 19.45 ± 2.10 mg/kg) and 4 h in plasma (0.184 ± 0.061 mg/L). Based on a minimum inhibitory concentration (MIC) of cefotaxime of 4.13 mg/L against Vibrio parahaemolyticus (known to cause acute hepatopancreatic necrosis disease (AHPND) in white leg shrimp), it was observed that the time during which the hepatopancreas cefotaxime concentration was above the MIC was 23 h. An every 24 h cefotaxime treatment could thus be effective in fighting against this bacterium in shrimp. The withdrawal time of cefotaxime was determined after shrimp were fed with medicated feed once a day and twice a day for three consecutive days. Shrimp muscle was collected on day 1 and day 3 during medication and 1, 3, 7, 14 and 21 days after medication was stopped. Considering an MRL of 50 μg/kg, the withdrawal times were 8.5 degree-days (corresponding to 6.9 h at 29.5 °C) after shrimp were fed with medicated feed once a day for 3 days and 95.5 degree-days (77.7 h at 29.5 °C) after shrimp were fed with medicated feed twice a day for 3 days. Moreover, histological analysis revealed that feeding shrimp with cefotaxime at the given dose in once- or twice-a-day treatments did not negatively impact the shrimp hepatopancreas.

Changes of bacterial communities and bile acid metabolism reveal the potential “intestine-hepatopancreas axis” in shrimp

The interaction between the gut and the liver plays a significant role in individual health and diseases. Mounting evidence supports that bile acids are important metabolites in the bidirectional communication between the gut and the liver. Most of the current studies on the “gut-liver axis” have focused on higher vertebrates, however, few was reported on lower invertebrates such as shrimp with an open circulatory system. Here, microbiomic and metabolomic analyses were conducted to investigate the bacterial composition and bile acid metabolism in intestine, hemolymph and hepatopancreas of Penaeus vannamei fed diets supplemented with octanoic acid and oleic acid. After six days of feeding, the bacterial composition in intestine, hemolymph and hepatopancreas changed at different stages, with significant increases in the relative abundance of several genera such as Pseudomonas and Rheinheimera in intestine and hepatopancreas. Notably, there was a more similar bacterial composition in intestine and hepatopancreas at the genus level, which indicated the close communication between shrimp intestine and hepatopancreas. Meanwhile, higher content of some bile acids such as lithocholic acid (LCA) and α-muricholic acid (α-MCA) in intestine and lower content of some bile acids such as taurohyocholic acids (THCA) and isolithocholic acid (IsoLCA) in hepatopancreas were detected. Furthermore, Spearman correlation analysis revealed a significant correlation between bacterial composition and bile acid metabolism in intestine and hepatopancreas. The microbial source tracking analysis showed that there was a high proportion of intestine and hepatopancreas bacterial community as the source of each other. Collectively, these results showed a strong crosstalk between shrimp intestine and hepatopancreas, which suggests a unique potential “intestine-hepatopancreas axis” in lower invertebrate shrimp with an open circulatory system. Our finding contributed to the understanding of the interplay between shrimp intestine and hepatopancreas in the view of microecology and provided new ideas for shrimp farming and disease control.

Shrimp Farmer’s Perceptions and Adaptation Strategies to the Threat of Climate Change in Bangil District, East Java

As one of the main stakeholders in the fishing industry, shrimp farmers are directly affected by climate change that causes changes in seawater temperature, rainfall, and unpredictable weather patterns. Related to the issue, the threat to income may be felt by shrimp farmers. Therefore, in this study, we highlight two objectives as a basis for drawing up this article, namely (1) to understand shrimp farmers’ perceptions of climate change, and (2) to identify factors that influence farmers’ decisions in implementing adaptation strategies. There are two types of analysis that we use, namely descriptive analysis and logit regression analysis. Our findings show that the majority of shrimp farmers consider climate change manifested in the form of changes in rainfall patterns (96.21%), increases in pond water temperatures (98.71%), decreases in yield production (95.41%), and increases in shrimp pests and diseases (96.23%). The results of our logit regression analysis show that the decision-making factors of shrimp farmers are significantly influenced. These results indicate that the implementation of adaptation strategies in the fisheries sector can generate significant growth and reduce the risks posed by climate change. As a result, the government needs to encourage the development of more suitable climate change adaptation strategies for small-scale shrimp farmers in Indonesia.

Nanoparticles‐based double‐stranded RNA delivery as an antiviral agent in shrimp aquaculture

AbstractThe review encapsulates the comprehensive exploration of RNA interference technology's application in shrimp aquaculture, covering molecular intricacies, production methods, and practical applications. The emphasis is on exploring the stability and delivery of gene‐specific double‐stranded RNA, particularly through nanoencapsulation. This is because the susceptibility of dsRNA to degradation and limited cellular penetration, emphasising the need for effective delivery mechanisms. The review presents an in‐depth exploration of nanoparticles for the encapsulation and delivery of dsRNA, including virus‐like particles (VLPs), and non‐viral based nanoparticles such as liposomes, chitosan, and beta‐glucan. VLPs, derived from non‐infectious shrimp virus structures, exhibit biocompatibility and natural functionality, making them suitable carriers for dsRNA. The application of chitosan and its derivatives are explored for their efficacy in reducing viral infections in shrimp. Beta‐glucan particles are examined for their immunostimulant properties in shrimp aquaculture. The text emphasises the use of yeast‐based glucan particles for encapsulating dsRNA, showcasing their potential in preventing viral diseases in shrimp. The review introduces cautionary considerations for nanoparticle formulation, highlighting factors such as pH, organic solvents, metal ions, and environmental ribonuclease that can impact dsRNA stability during synthesis. In conclusion, the text discusses the potential economic worthiness and environmental risk assessment of dsRNA technology in shrimp aquaculture. While acknowledging successful applications in other environments, it underscores the need for regulatory approval and risk assessment for dsRNA‐based products in the aquaculture industry. The evaluation of dsRNA in real‐world shrimp farms is deemed necessary for commercial utilisation, taking into account income, expenses, safety, and environmental considerations.

Investigation of the Protective Effect of Probiotic Lactobacillus plantarum Ep-M17 on the Hepatopancreas of Penaeus vannamei

Infection with the pathogenic bacterium Vibrio parahaemolyticus typically causes severe hepatopancreatic damage in Penaeus vannamei, often resulting in acute shrimp mortality. Therefore, protecting the shrimp’s hepatopancreas is crucial for enhancing their disease resistance. Previous research has demonstrated that the probiotic strain Lactobacillus plantarum Ep-M17 inhibits the growth of V. parahaemolyticus E1 in vitro. However, it remains uncertain whether Ep-M17 can provide protective benefits to the shrimp’s hepatopancreas. To address this knowledge gap, our present study investigated the histological changes, enzyme activity, gene transcription, and metabolite levels in the hepatopancreas of shrimp after a 4-week diet supplemented with Ep-M17. The results revealed that incorporating Ep-M17 into the shrimp’s diet alleviated the damage by V. parahaemolyticus E1 infection in hepatopancreatic cells. In addition, the inclusion of Ep-M17 notably boosted the effectiveness of immunodigestive enzymes such as SOD, AKP, and CAT. Furthermore, Ep-M17 stimulated gene transcription in crucial immune response-related signalling pathways like the mitogen-activated protein kinase signaling pathway and the antigen processing and presentation pathway. Moreover, the incorporation of Ep-M17 into shrimp diets increased the levels of β-alanine, and histidine in the hepatopancreas, enhancing anti-inflammatory capacity and improving the shrimp’s immune response. Overall, the results indicate that incorporating Ep-M17 into the diet can enhance shrimp disease resistance by bolstering both immune response and metabolic activity within the hepatopancreas. These results underscore the importance of probiotics in controlling aquatic animal diseases and highlight Ep-M17 as a promising dietary supplement for enhancing shrimp health and immunity in aquaculture.