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Acute Hepatopancreatic Necrosis Disease (AHPND) represents a significant challenge in the field of shrimp aquaculture. This disease is primarily caused by Vibrio parahaemolyticus strains harbouring the pVA1 plasmid encoding the PirAvp and PirBvp toxins. To combat this epidemic and mitigate its devastating consequences, it is crucial to identify and characterize the receptors responsible for the binding of these pathogenic toxins. Our studied discovered that Penaeus vannamei's Serine protease inhibitor 3 (PvSerpin3) derived from shrimp hepatopancreatic tissues could bind to recombinant PirAvp, confirming its role as a novel PirAvp‐binding protein (PABP). Through comprehensive computational methods, we revealed two truncated PirAvp–binding proteins derived from PvSerpin3 called Serpin3(13) and Serpin3(22), which had higher affinity to PirAvp than the full‐length PvSerpin3. The PABP genes were amplified from a cDNA library that was reversed from total RNA extracted from shrimp, cloned and expressed in Escherichia coli. Three PABP inclusion bodies were refolded to obtain the soluble form, and the recovery efficacy was found to be 100% for Serpin3 and Serpin3(13), while Serpin3(22) had a recovery efficacy of roundly 50%. Co‐Immunoprecipitation (co‐IP) and dot blot assays substantiated the interaction of these recombinant PABPs with both recombinant PirAvp and VPAHPND (XN89)‐producing natural toxins. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is equipped with two distinct flagellar systems: a polar flagellum and numerous lateral flagella. The polar flagellum plays a role in propelling swimming in liquids, while the lateral flagella serve to enhance swarming on surfaces or in viscous environments. H-NS is a histone-like nucleoid structuring protein that plays a regulatory role in both the swimming and swarming motility of V. parahaemolyticus. However, the detailed mechanisms have not been fully understood. In this study, we have demonstrated that the deletion of hns hindered the growth rate of V. parahaemolyticus during the logarithmic growth phase and significantly decreased the swimming motility. H-NS directly activated the transcription of flgMN, flgAMN, flgBCDEFGHIJ, and flgKL-flaC located within the polar flagellar gene clusters. The expression of H-NS in Escherichia coli led to a marked elevation in the expression levels of flgM, flgA, flgB, and flgK, suggesting the positive effect of H-NS on the expression of polar flagellar genes in E. coli. This work demonstrates that the positive regulation of H-NS on the swimming motility in V. parahaemolyticus may be achieved through its regulation of polar flagellar gene expression and bacterial growth. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is a significant pathogen affecting shrimp and crab farming, particularly strains carrying genes associated with acute hepatopancreatic necrosis syndrome. However, the immune response of Eriocheir sinensis to V. parahaemolyticus infection remains unclear. To address this knowledge gap, an experiment was conducted to establish a V. parahaemolyticus infection model. This model aimed to compare pathological damage and enzyme activity changes in E. sinensis hepatopancreas tissue at various infection time points, and to examine transcriptome changes in individuals exhibiting different clinical symptoms of infection. The results showed that intramuscular injection of 1.78 × 106 CFU/mL of V. parahaemolyticus for 24 hours resulted in a 50% mortality rate among the experimental animals. Pathological findings revealed that the infection led to a change in color of the hepatopancreas tissue from bright yellow to white, diffuse tissue cell distribution, and hepatopancreatic necrosis. Additionally, there was a significant increase in the activities of alanine aminotransferase and aspartate aminotransferase in the hepatopancreas (P < 0.01). Furthermore, the activities of superoxide dismutase, total antioxidant capacity, phenoloxidase, alkaline phosphatase, and acid phosphatase initially increased and then decreased. RNA-seq analysis revealed 11,662 differentially expressed genes compared to the susceptible group and control group, with 6,266 genes up-regulated and 5,396 genes down-regulated. When comparing the susceptible group to the disease-resistant group, 13,515 differentially expressed genes were identified, with 7,694 genes up-regulated and 5,821 genes down-regulated. Finally, comparison between the disease-resistant group and control group yielded 13,515 differentially expressed genes, with 7,631 genes up-regulated and 3,111 genes down-regulated. Differential gene enrichment analysis revealed pathways such as phagosomes, cancer pathways, proteoglycans in cancer, ribosomes, protein processing in the endoplasmic reticulum, starch and sucrose metabolism, and lysosome signaling pathways. Furthermore, 342 immune-related genes with differential expression were identified, primarily enriched in 22 pathways linked to cell signaling. These genes play a crucial role in defense against bacterial invasion and immune response regulation through various signaling pathways. Overall, this study provides valuable insights into the defense mechanisms and understanding of Chinese mitten crab immunity against bacterial infection by examining changes in mRNA, enzyme activity, and hepatopancreatic damage during infection. [ABSTRACT FROM AUTHOR]

Acute Hepatopancreatic Necrosis Disease (AHPND) represents a significant challenge in the field of shrimp aquaculture. This disease is primarily caused by Vibrio parahaemolyticus strains harbouring the pVA1 plasmid encoding the PirAvp and PirBvp toxins. To combat this epidemic and mitigate its devastating consequences, it is crucial to identify and characterize the receptors responsible for the binding of these pathogenic toxins. Our studied discovered that Penaeus vannamei's Serine protease inhibitor 3 (PvSerpin3) derived from shrimp hepatopancreatic tissues could bind to recombinant PirAvp, confirming its role as a novel PirAvp‐binding protein (PABP). Through comprehensive computational methods, we revealed two truncated PirAvp–binding proteins derived from PvSerpin3 called Serpin3(13) and Serpin3(22), which had higher affinity to PirAvp than the full‐length PvSerpin3. The PABP genes were amplified from a cDNA library that was reversed from total RNA extracted from shrimp, cloned and expressed in Escherichia coli. Three PABP inclusion bodies were refolded to obtain the soluble form, and the recovery efficacy was found to be 100% for Serpin3 and Serpin3(13), while Serpin3(22) had a recovery efficacy of roundly 50%. Co‐Immunoprecipitation (co‐IP) and dot blot assays substantiated the interaction of these recombinant PABPs with both recombinant PirAvp and VPAHPND (XN89)‐producing natural toxins. [ABSTRACT FROM AUTHOR]

Copyright of Veterinarska Stanica is the property of Croatian Veterinary Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A pathology characterized by multifocal reddish patches on the cuticle of shrimp has been reported by shrimp farmers in Latin America. These red patches are commonly associated with small black necrotic spots and white muscle necrosis. One significant impact of this pathology is the reduction in shrimp prices due to the appearance of the animals before and after cooking. The disease is more prevalent in areas with salinities above 5 ppt, with one farm reporting a 45% incidence in one pond. Histopathological examination revealed infiltration of hemocytes in the muscle tissue, melanosis, muscle necrosis, and the presence of Gram‐negative rods in the muscle tissue. Given the presence of bacteria and negative polymerase chain reaction (PCR) results for muscle‐infecting viruses such as infectious myonecrosis virus (IMNV) and Penaeus vannamei nodavirus (PvNV), this pathology is likely due to bacterial infection, though environmental stressors cannot be ruled out as contributing factors in this complex condition. Several Vibrio strains were isolated from the affected tissue and identified using API 20E and PCR. Two strains were selected for in vivo experimentation: Vibrio parahaemolyticus (C8Cg, PirAB toxin‐positive) and V. alginolyticus (C3Ver, PirAB toxin‐negative). Shrimp injected with both live and autoclaved bacteria showed similar histopathological changes, suggesting that the pathology is due to virulence factors within the bacterial cells that can still provoke a strong immune or toxic response even in the absence of live, actively replicating bacteria. [ABSTRACT FROM AUTHOR]

Gut bacterial lipopolysaccharide (LPS) could be released into the circulatory system via the gut–liver axis and cause inflammatory immune response, while Cordyceps militaris polysaccharide (CMP40) has been reported to be effective in alleviating this inflammatory response. In this study, the effects of CMP40 gut fermentation on internal LPS structure formation and the subsequent immune response were explored. Results showed that CMP40 could change antigenicity of LPS of Vibrio parahaemolyticus, Salmonella enterica, and enterotoxigenic Escherichia coli, indicated by a reduced level of NO, IL‐1β, IL‐6, and TNF‐α. The LPS structure of these three strains were further elucidated. ESI/MS results revealed that CMP40 fermentation could alter the LPS structure by removing phosphate group from a single Kdo sugar or removing additional sided fatty acid chain. The gene expressions of enzymes that are responsible for group transfer further confirmed this structure modification process. This study focused on the regulation of polysaccharide on gut bacteria LPS and provided a new insight into health effect of CMP40. [ABSTRACT FROM AUTHOR]

Introduction: The intricate habitats of aquatic organisms, coupled with the prevalence of pathogens, contribute to a high incidence of various diseases, particularly bacterial infections. Consequently, the formulation of sustainable and effective disease management strategies is crucial for the thriving aquaculture sector. Methods and results: In this investigation, a strain of Bdellovibrio bacteriovorus , designated B. bacteriovorus FWA , was isolated from a freshwater fish pond. Identification was achieved through microscopic examination of morphological characteristics, biochemical property assessment, and phylogenetic analysis. The lysogenic capability of B. bacteriovorus FWA was evaluated, revealing its effectiveness in lysing Escherichia coli , Aeromonas hydrophila , Vibrio alginolyticus , Vibrio parahaemolyticus , and Edwardsiella tarda. Physiological analysis indicated that the optimal ratio of B. bacteriovorus FWA to host bacteria was 1:10,000, with strict aerobic requirements. The optimal pH range for growth and reproduction was 7.0–8.0, the ideal temperature was found to be 30–35°C, with a preferred Na+ concentration of 0% and a Ca2+ concentration of 15–25 mM. Additionally, B. bacteriovorus FWA demonstrated enhanced lytic activity against bacteria in aquaculture effluent while effectively managing ammonia-nitrogen levels. Discussion: In summary, B. bacteriovorus FWA holds significant promise for development as a probiotic agent in aquaculture. [ABSTRACT FROM AUTHOR]

Ecytonucleospora hepatopenaei (EHP), a microsporidian parasite first named and characterized from the Penaeus monodon (black or giant tiger shrimp), causes growth retardation and poses a significant threat to shrimp farming. We observed shrimp farms associated with disease conditions during our fish disease surveillance and health management program in West Bengal, India. Shrimp exhibited growth retardation and increased size variability, particularly in advanced stages, exhibiting soft shells, lethargy, reduced feeding and empty midguts. Floating white feces were observed on the surface of the pond water. Suspecting a microbial infection, the shrimp samples were collected and aseptically brought to the ICAR-CIFRI laboratory for molecular confirmation. A nested PCR was used to screen shrimp tissue, feces, feed and environmental samples for the possible presence of hepatopancreatic microsporidiosis caused by Ecytonucleospora hepatopenaei. The results confirmed that the shrimp samples were positive for EHP. Histopathological investigation revealed mature spores in the HP tubule lumen and epithelial cells along with necrotic tubule in the symptomatic group. Further, the transcription analysis revealed that ProPO, Hsp70 and α2-macroglobulin genes were significantly upregulated, while decreased expression of LGBP, PXN and Integrin ß was observed in shrimp infected with Hepatopancreatic microsporidiosis. Furthermore, compared with the healthy group, significant intestinal bacteria changes were observed in the EHP-infected group. The in vivo survival assay, using crustacean animal model Artemia franciscana, suggests that symptomatic shrimp gut samples harbour pathogenic Vibrio parahaemolyticus, V. harveyi and V. campbellii. These results significantly advance our understanding of the molecular and ecological aspects of EHP pathobiology. [ABSTRACT FROM AUTHOR]

Type VI secretion system 2 (T6SS2) of Vibrio parahaemolyticus is required for cell adhesion and autophagy in macrophages; however, other phenotypes conferred by this T6SS have not been thoroughly investigated. We deleted TssL2, a key component of T6SS2 assembly, to explore the role of the T6SS2 in environmental adaptation and virulence. TssL2 deletion reduced Hcp2 secretion, suggesting that TssL2 played an important role in activity of functional T6SS2. We found that TssL2 was necessary for cell aggregation, wrinkly phenotype formation, and participates in motility and biofilm formation by regulating related genes, suggesting that TssL2 was essential for V. parahaemolyticus to adapt changing environments. In addition, this study demonstrated TssL2 significantly affected adhesion, cytotoxicity, bacterial colonization ability, and mortality in mice, even the levels of the proinflammatory cytokines IL-6 and IL-8, suggesting that TssL2 was involved in bacterial virulence and immunity. Proteome analysis revealed that TssL2 significantly affected the expression of 163 proteins related to ABC transporter systems, flagellar assembly, biofilm formation, and multiple microbial metabolism pathways, some of which supported the effect of TssL2 on the different phenotypes of V. parahaemolyticus. Among them, the decreased expression of the T3SS1 and T2SS proteins was confirmed by the results of gene transcription, which may be the main reason for the decrease in cytotoxicity. Altogether, these findings further our understanding of T6SS2 components on environmental adaption and virulence during bacterial infection. Key points: • The role of T6SS2 in V. parahaemolyticus was far from clear. • TssL2 participates in cell aggregation, wrinkly phenotype formation, motility, and biofilm formation. • TssL2 is essential for cell bacterial colonization, cytotoxicity, virulence, and proinflammatory cytokine production. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus is associated with severe food-borne illness in humans as well as substantial financial setbacks in the fishing sector. To investigate the prevalence, pathogenicity, virulence, as well as the resistance patterns of V. parahaemolyticus retrieved from Oreochromis niloticus, 180 O. niloticus (moribund fish; n = 120 and apparently healthy; n = 60) were indiscriminately collected from Lake Manzala, Egypt. Consequently, the clinical inspection, necropsy finding, and bacteriological analysis were performed. All the retrieved isolates tested positive for the groEL species-specific gene. Herein, the prevalence of V. parahaemolyticus in the collected fish was 8.9% (16/180), whereas the liver was the organ most prominently affected. PCR revealed that the most prevalent virulence-determinant genes associated with V. parahaemolyticus were the toxR and tlh genes (100% for each), then tdh (73.3%) and trh (26.7%) genes. Furthermore, 40% (18/45) of isolated V. parahaemolyticus were extensively drug-resistant (XDR) to seven antimicrobial classes and have blaTEM, blaOXA, sul1, aadA, ermB, and tetA genes. Additionally, 17.8% (8/45) of the obtained V. parahaemolyticus were multidrug-resistant (MDR) to three antimicrobial classes and owned blaTEM, ermB, and aadA genes. The pathogenicity assay accentuated the correlation between cumulative mortality and the virulent characteristics exhibited by the inoculated strain. Definitely, 77% mortality was recorded within eight days in fish injected with a virulent V. parahaemolyticus strain. Briefly, this research accentuated the occurrence of XDR V. parahaemolyticus in fish specifying a public health concern. The emerging MDR and XDR V. parahaemolyticus frequently harbored toxR, tlh, and tdh virulence genes, and blaTEM, blaOXA, sul1, aadA, ermB, and tetA or tetB antimicrobial resistance genes. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: Hypoxia stress renders aquatic animals more susceptible to bacterial disease, yet the underlying mechanism remains elusive. Methods: We conducted an acute hypoxia stress experiment to investigate the impact of stress on the immune response of Litopenaeus vannamei via transcriptome analysis, RT-qPCR and Western blot. Results: Our results showed that acute hypoxia stress disrupted the tissue architecture, and significantly changed the gene expression profiles in the hepatopancreas of shrimp. More importantly, acute hypoxia stress significantly changed the expression levels of immune-related genes. Ladderlectin , GBP 1 , Caspase-1 , CLEC4F , MR1 and GBP 2 were significantly down-regulated, but HIF-1α , Cactus , TIPE , Akirin-2 , Ivns1abp and TLR3 were significantly up-regulated. We further demonstrated that acute hypoxia activated Yki via HIF-1α to enhance expression level of Cactus , and then Cactus inhibited the phosphorylation of Dorsal and its nuclear translocation, thereby suppressing antibacterial immunity. Subsequently, the challenge experiment following stress revealed that exposure to acute hypoxia stress amplified the infectivity and lethality of Vibrio parahaemolyticus to shrimp. The mechanism of HIF-1α-Yki-Cautus axis provided an explanation for this phenomenon. Discussion: This study offered new insights into interactions among environmental hypoxia stress, host immunity and pathogens, thereby providing practical guidelines for optimizing shrimp culture practices. [ABSTRACT FROM AUTHOR]

Pacific white shrimp (Penaeus vannamei) is one of the most productive and economically important species globally. However, the development and continuous expansion of the farming scale led to an increase in the risk of disease occurrence in shrimp farming. The application of probiotics as an effective method for controlling diseases in aquaculture has been widely considered. In shrimp farming, several probiotics have been used and shown benefits to the health of the host. To diverse the sources of bacterial species as probiotics in shrimp farming, in this study, we aimed to elucidate the effects of dietary probiotics (Clostridium butyricum I9 (I9), Clostridium butyricum G15 (G15), or Paraclostridium bifermentans X13) on the growth, immune response and intestinal microbiome of white shrimp. Shrimps were fed with diets containing either phosphate-buffered saline (PBS), I9 (107 CFU/g feed), G15 (107 CFU/g feed), or X13 (107 CFU/g feed) for 30 days and followed by the challenge with Vibrio parahaemolyticus (Vp). The results showed that the survival rate, body weight gain, and special growth rate of shrimps in the I9, X13, and G15 groups significantly increased, compared to the PBS. The supplementation of probiotics increased the content of short-chain fatty acids and effectively maintained the normal morphology and structure of the intestinal tract and hepatopancreas. The I9, X13, or G15 groups showed a positive change in the diversity and abundance of gut bacteria. There was a significant up-regulation of CTL, SOD, proPO, Crustin, PEN2-4, and ALF1-3 genes in shrimps in the I9, X13, and G15. Additionally, dietary probiotics significantly increased the survival rate, maintained the intestinal structure, promoted the activities of SOD, AKP, ACP, and T-AOC enzymes, and reduced the level of MDA in shrimps after Vp infection. In conclusion, dietary supplementation of I9, G15, or X13 improved the growth, immunity, and disease resistance of Pacific white shrimp, providing a scientific basis for shrimp farming. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of dietary synbiotics on enhancing digestive enzymes, reducing the overall bacterial count of Vibrio, and minimizing hepatopancreatic histological damage caused by V. parahaemolyticus in shrimp (Penaeus vanamei). The experiments involved administering different treatments, namely Bacillus NP5 (SBM), Pseudoalteromonas piscicida1Ub (SPM), and Bacillus NP5 and P. piscicida 1Ub (SBPM), incombination with the prebiotic mannan oligosaccharide (MOS). This study was conducted for 60 days, followed by a challenge test with Vibrio parahaemolyticus for 7 days. The results of the experiments showed that dietary synbiotic supplementation demonstrated better digestive enzyme activity and histology of the hepatopancreas compared to controls (p < .05). After the challenge test, it was found that the damage to the hepatopancreatic tissue of shrimps was less severe and the total vibrio count was lower in the synbiotic treatment, indicating a protective effect compared to the positive controls (p < .05). In conclusion, the use of dietary synbiotics had the potential to enhance digestive enzyme function and provide disease protection for Penaeus vannamei shrimp. [ABSTRACT FROM AUTHOR]

The coordination of cell cycle progression and flagellar synthesis is a complex process in motile bacteria. In γ-proteobacteria, the localization of the flagellum to the cell pole is mediated by the SRP-type GTPase FlhF. However, the mechanism of action of FlhF, and its relationship with the cell pole landmark protein HubP remain unclear. In this study, we discovered a novel protein called FipA that is required for normal FlhF activity and function in polar flagellar synthesis. We demonstrated that membrane-localized FipA interacts with FlhF and is required for normal flagellar synthesis in Vibrio parahaemolyticus, Pseudomonas putida, and Shewanella putrefaciens, and it does so independently of the polar localization mediated by HubP. FipA exhibits a dynamic localization pattern and is present at the designated pole before flagellar synthesis begins, suggesting its role in licensing flagellar formation. This discovery provides insight into a new pathway for regulating flagellum synthesis and coordinating cellular organization in bacteria that rely on polar flagellation and FlhF-dependent localization. [ABSTRACT FROM AUTHOR]

Background: Vibrio parahaemolyticus has emerged as the leading cause of seafood-associated infections worldwide. Previous studies have shown that V. parahaemolyticus can be detected in both environmental and clinical samples. However, the molecular characteristics of V. parahaemolyticus isolated from these sources remain unknown. Results: This study examined 128 strains of V. parahaemolyticus isolated from clinical and environmental samples collected between 2020 and 2023 in Huzhou, China. We identified 73 serotypes; O10:K4, O3:K6, and O4:KUT were the dominant serotypes among clinical isolates. We examined the proliferation and motility of major epidemic strains from environmental and clinical samples. Genetic diversity and evolution were assessed by average nucleotide identity (ANI), phylogenetic tree construction, and multilocus sequence typing (MLST). Furthermore, we identified 13 novel sequence types (STs) among the environmental isolates, indicating that V. parahaemolyticus strains are widely distributed and evolve rapidly in the environment in Huzhou, China. We found 206 virulence genes among these isolates, indicating that environmental isolates possess numerous virulence genes. Additionally, we detected 4 strains carrying the tdh or trh gene, which may increase their pathogenicity. The prediction results of antibiotic resistance genes shown that environmental isolates may carry up to 104 resistance genes, compared to 30 in clinical isolates. Conclusions: We observed that the environmental serotypes of V. parahaemolyticus exhibit greater diversity compared to clinical isolates, which are predominantly concentrated in three major serotypes. Furthermore, a considerable genetic distance was found between most clinical and environmental isolates. Notably, some clinical isolates show a closer genetic proximity to environmental isolates. Additionally, the distribution of virulence genes, specifically T3SS and tdh, significantly differs among isolates from these two distinct sources. The prediction results for antibiotic resistance genes suggest that environmental isolates may harbor a broader spectrum of resistance genes. The findings of this study provide new insights into the phylogenetic relationships between V. parahaemolyticus strains from clinical and environmental sources, and they enhance the MLST database. [ABSTRACT FROM AUTHOR]

As one of the most harmful pathogenic bacteria in shrimp aquaculture, Vibrio parahaemolyticus often causes massive mortality in shrimp. Accurate and rapid detection of V. parahaemolyticus in shrimp farming is essential for avoiding huge economic losses caused by related diseases. In this study, we designed a dual-recognition platform for efficient identification and quantification of V. parahaemolyticus. First, the target bacterium was captured with magnetic beads functionalized by aptamers (Apt-MBs), and then, the broad-spectrum fluorescent probe FcMBL@CdSe-ZnS was used to detect the bacterium based on the interactions between fragment crystallizable mannose-binding lectin (FcMBL) and pathogenic bacteria. The proposed dual-recognition strategy centered around aptamers and FcMBL@CdSe-ZnS was applied to definite quantification of V. parahaemolyticus over a wide range of 10–108 CFU/mL with a limit of detection of 4 CFU/mL within 55 min. The feasibility was demonstrated by using the platform to detect V. parahaemolyticus from shrimp intestine, aquaculture water, and seawater. [ABSTRACT FROM AUTHOR]

AiiA can be targeted to quench N-acyl-homoserine lactones (AHLs) quorum sensing signaling molecules. In this paper, we extracted and purified AiiA protein by constructing recombinant engineering bacteria to analyze the effect of AiiA on the formation of Vibrio parahaemolyticus biofilm. The results suggest that AiiA has a particular potential in inhibiting the formation of biofilms and extracellular polymers. The ability of AiiA to inhibit biofilm increased and then decreased, with the lowest biofilm decomposition concentration of 8 μg/mL and the optimal inhibitor concentration of 85 μg/mL (86.9% biofilm inhibition). LC-MS results showed that when the concentration of C4-HSL in Vibrio parahaemolyticus ATCC33847 biofilm exceeded 3.70 μg/L, the content of quorum sensing signaling molecules reached a threshold and began to activate LuxR protein to regulate the expression of related genes. These results provide relevant experimental guidance for the clinical treatment of biofilm infections and the development of novel QS inhibitors. [ABSTRACT FROM AUTHOR]

This study aims to develop an alternative aquafeed derived from insect meal for Lates calcarifer juveniles, with the objectives of exploring the physiological performance, biological parameters, and economic analysis of substituting fishmeal (FM) with defatted black soldier fly (Hermetia illucens) larvae (BSFL) as part of the diet of L. calcarifer juveniles. Five practical diets were formulated to include 0% (BSFL0, serves as control group), 5% (BSFL5), 10% (BSFL10), 15% (BSFL15), and 20% (BSFL20) of BSFL meal, partially or fully replacing FM, respectively. Each diet was randomly assigned to triplicate groups of 30 fish (10.70 ± 0.07 g) per tank (300 L). The fish were fed twice daily to apparent satiation. A 56‐day feeding trial was conducted to evaluate the impacts of defatted BSFL meal replacing FM on the growth performance, feed efficiency, composition analysis of fish muscle, cumulative mortality rate challenged with Vibrio parahaemolyticus, and economic returns of L. calcarifer. These results show that differences in weight gain and specific growth rate among the different treatments were statistically significant (p < 0.05), except for the absence of significant variation (p < 0.05) between BSFL0 and BSFL5, and followed by BSFL10 > BSFL0 > BSFL5 > BSFL15 > BSFL20. However, the feed conversion ratio and protein efficiency ratio showed the opposite trend as above. Although the diets experienced a decline in crude protein content and an increase in crude fat content with the increasing proportion of BSFL substituting FM, the crude protein and fat content of fish muscle were only slightly influenced. It is worth mentioning that levels of nonessential amino acids, delicious amino acids, saturated fatty acids, omega‐6, omega‐9 in BSFL10 group all showed an increase compared with the control group. After a 7‐day challenge test with V. parahaemolyticus, the cumulative mortality rates of the BSFL5 and BSFL10 groups, respectively, dropped to 5.20%, 5.28% compared to the control group's 16.88%; however, the mortality rates of BSFL15 (34.67%) and BSFL20 (41.77%) groups were found to be significantly (p < 0.05) increased. From an economic perspective, the incidence cost for each experimental group showed a trend as BSFL10 < BSFL0 < BSFL5 < BSFL15 < BSFL20, whereas the profit index in each treatment exhibited the opposite trend as above. It was concluded that low (5%) or moderate (10%) levels of BSFL substituting FM in aquaculture feed could improve the physiological performances, disease resistance, and economic returns of L. calcarifer. However, excessive substitution (>15%) leads to a negative effect. From an economic point of view, 10% inclusion of BSFL in practical diets is recommended for L. calcarifer juveniles. [ABSTRACT FROM AUTHOR]

The study published in the Journal of Travel Medicine explores the acquisition of antimicrobial resistance (AMR) genes among Dutch intercontinental travellers. The research, conducted within the Carriage Of Multiresistant Bacteria After Travel (COMBAT) study, involved 2001 Dutch travellers visiting various regions. The study found that travellers to certain regions, such as Southern Asia, were more likely to acquire AMR genes, highlighting the importance of understanding the interconnection between travel, human behavior, and nutrition in AMR transmission. [Extracted from the article]

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]

Sexual dimorphism is a common feature in all crustaceans. However, little information is available on the relationship between sex and disease resistance in Litopenaeus vannamei. This study aimed to evaluate the differences in innate immunity characteristics between male and female L. vannamei under stimulation with Vibrio parahaemolyticus causing acute hepatopancreatic necrosis disease (VpAHPND) or lipopolysaccharide (LPS). We found that the survival rates of female shrimp were significantly higher than those of males during VpAHPND stimulation (P < 0.05). In transcriptome analysis, we discovered obvious differences in the pathways activated for immune and metabolic responses between male and female shrimp after VpAHPND stimulation. Genes associated with immunity were downregulated in the VM (male stimulation group) vs. BM (male control group) comparison, whereas they were upregulated in the VF (female stimulation group) vs. BF (female control group) comparison. Furthermore, the transcriptome results showed that changes in processes such as carbohydrate metabolism and amino acid metabolism were also different between females and males. After LPS stimulation, the contents of semi-granular cells (SGCs) significantly decreased while those of granular cells (GCs) significantly increased in male shrimp, while the number of hyaline cells (HCs) decreased in female shrimp. The phagocytosis rate of hemocytes in male shrimp significantly decreased, while the catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO), and glutathione S-transferase (GSH-ST) contents in the plasma of female shrimp were higher than those in males. These results collectively indicate that female shrimp have superior disease resistance compared to males, which provides an important reference for subsequent breeding efforts aimed at enhancing disease resistance in L. vannamei. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus has two flagellar systems, the polar flagellum and lateral flagella, which are both intricately regulated by a multitude of factors. CalR, a LysR-type transcriptional regulator, is sensitive to calcium (Ca) and plays a crucial role in regulating the virulence and swarming motility of V. parahaemolyticus. In this study, we have demonstrated that the deletion of calR significantly enhances the swimming motility of V. parahaemolyticus under low Ca conditions but not under high Ca conditions or in the absence of Ca. CalR binds to the regulatory DNA regions of flgM, flgA, and flgB, which are located within the polar flagellar gene loci, with the purpose of repressing their transcription. Additionally, it exerts an indirect negative control over the transcription of flgK. The overexpression of CalR in Escherichia coli resulted in a reduction in the expression levels of flgM, flgA, and flgB, while having no impact on the expression of flgK. In summary, this research demonstrates that the negative regulation of V. parahaemolyticus swimming motility by CalR under low Ca conditions is achieved through its regulation on the transcription of polar flagellar genes. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus, a significant cause of gastroenteritis and a growing public health concern, has become increasingly prevalent owing to the rise in ocean temperatures driven by climate change. This study aimed to characterize the genetic diversity, pathogenic potential, and antimicrobial resistance (AMR) profiles of V. parahaemolyticus strains isolated from the southern coastal region of Korea. Using whole genome sequencing (WGS) and advanced bioinformatics tools, we identified novel sequence types through multilocus sequence typing and serotyped isolates using the VPsero database. Pathogenic genes, such as tdh and trh, were detected in only a few isolates, suggesting the involvement of alternative virulence mechanisms in the pathogenicity of these strains. An in silico analysis revealed widespread AMR, particularly against beta-lactams, chloramphenicol, and tetracycline antibiotics, underscoring the public health threats posed by these strains. A phylogenetic analysis revealed no significant clustering by geographic origin, year, or strain source, although most clinical and environmental strains were not closely related at lower phylogenetic branches. These findings highlight the importance of continued genomic surveillance and strict regulations regarding antibiotic use in marine environments. Moreover, this study suggests that integrating WGS data with epidemiological models could enhance the prediction of the emerging virulent strains and support effective outbreak management strategies. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus (V. parahaemolyticus) is a significant concern, as it can cause severe infections and hemolytic trauma. Given its prevalence in seawater and coastal seafood, it poses a substantial risk as a foodborne pathogen. Biosensor-based detection technology has been continuously evolving, and toehold switches have emerged as a promising area within it, especially in the detection of RNA viruses. Here, we have developed a cell-free toehold switch sensor for V. parahaemolyticus detection. Traditional toehold switch detection methods usually use green fluorescent protein (GFP) or enzyme LacZ as the output signal, with an incubation time as long as 2 h, and are also mainly applied to the detection of RNA viruses. In this study, we introduced a novel, artificially designed luciferase (LuxSit-i) as an output signal and constructed toehold switches with two different output signals (sfGFP, LuxSit-i), aimed at reducing the incubation time of toehold switches. Moreover, to further improve the detection process, we separately utilize recombinase polymerase amplification (RPA) and nucleic acid sequence-based amplification (NASBA) to amplify dead and live bacterial suspensions for detection and attempt to distinguish between dead and live bacteria. This study provided a convenient, rapid, and accurate method for the on-site detection of V. parahaemolyticus, especially beneficial for resource-limited settings. By eliminating the requirement for specialized facilities and personnel, this system has the potential to be a valuable tool in improving public health responses, especially in developing regions. [ABSTRACT FROM AUTHOR]

Vibrio disease is a prevalent bacterial infection in aquaculture, and using bacteria with antagonistic properties against Vibrio species as probiotics has emerged as a promising method for disease prevention. Additionally, low biomass productivity of microalgae feed remains a significant bottleneck in bivalve aquaculture. Therefore, it is essential to screen for bacteria that both enhance microalgae growth and inhibit Vibrio pathogens. In this study, seven bacterial strains capable of promoting microalgae growth were screened for their ability to inhibit three Vibrio pathogens, i.e., Vibrio vulnificus, Vibrio parahaemolyticus and Vibrio cholerae , and thus serve as a dual-functional probiotic for aquaculture. The antagonistic mechanism of these bacteria was further investigated by analyzing the inhibitory effects of their extracellular products (ECP) on Vibrio species. Results indicated that Pseudoalteromonas flavipulchra exhibited antagonistic effects against all three Vibrio species tested. The ECP of P. flavipulchra displayed stable antibacterial activity, though this ability was lost after the ECP was treated with heat, alkali, or proteinase K. The proteinaceous fraction isolated from the ECP by precipitation with 90% saturated ammonium sulfate demonstrated concentration-dependent antibacterial activity. These findings suggest that P. flavipulchra could serve as a promising dual-functional probiotic for aquaculture, warranting further research to optimize its application in this field. [ABSTRACT FROM AUTHOR]

Vibrio parahaemolyticus (V. parahaemolyticus) is a major food-borne pathogen which causes human gastroenteritis. Since the characteristics of V. parahaemolyticus remain unknown, 220 isolates selected from clinical and environmental samples in Dapeng of Shenzhen were tested for the presence of two hemolysin-expressing genes tdh and trh. Among 27 clinical isolates, 26 carrired the tdh gene, and the other one carried both tdh and trh genes, however neither genes were detected in environmental isolates. Meanwhile, antimicrobial susceptibility profiles revealed the isolates with high frequency of resistance to ampicillin (77.73%) and colistin (71.82%) and medium to streptomycin (57.27%). Genetically, by whole genome sequencing (WGS), comparative genomics studies was performed on isolates from various districts and GenBank. Data analysis showed that antimicrobial resistance genes (ARGs) blaCARB , tet(34) and tet(35) were harbored in all genomes and other ARGs was absent in the genomes of 27 clinical isolates. Besides, little regional difference was observed. As for virulence factors, MAM7, T3SS1, T3SS1 secret effector, T3SS2, T3SS2 secret effector, and VpadF were carried by most isolates. Two isolates from other districts were tdh gene positive which clustered with clinical isolates from Dapeng in the same clade, indicating close genetic distance. This study revealed the widely distribution of V. parahaemolyticus in Shenzhen and the diverse ARGs and virulence genes it carried. Furthermore, pathways that pathogen disseminated through were discussed. [ABSTRACT FROM AUTHOR]

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Although phloretin is widely utilized in the food industry as an additive, its effects on foodborne pathogens remain insufficiently investigated. This study aimed to evaluate the antimicrobial properties of phloretin (PHL) against Vibrio parahaemolyticus (V. parahaemolyticus) and to elucidate the potential mechanisms of action. After PHL treatment, alterations in the cell morphology, cell microstructure, and intracellular contents of V. parahaemolyticus were assessed. Scanning electron microscopy revealed substantial damage to cell integrity, subsequent to PHL treatment. A notable reduction in intracellular components, including proteins, ATP, and DNA, was observed in samples treated with PHL. PHL was shown to inhibit the activities of ATPase, β-galactosidase, and respiratory chain dehydrogenase in V. parahaemolyticus. Furthermore, it was demonstrated to elevate the intracellular levels of reactive oxygen species and promote cell death. After being applied to sea bass, shrimp, and oysters, PHL effectively inactivated V. parahaemolyticus in these seafoods. These findings demonstrate that PHL has potential for application in seafood to control V. parahaemolyticus. [ABSTRACT FROM AUTHOR]