Aeromonas Hydrophila Infection Research Articles

Integrated time-series biochemical, transcriptomic, and metabolomic analyses reveal key metabolites and signaling pathways in the liver of the Chinese soft-shelled turtle (Pelodiscus sinensis) against Aeromonas hydrophila infection.

Aeromonas hydrophila, a bacterium widely distributed in the natural environment, causes multiple diseases in various animals. Exploring the mechanism of the host defense against A. hydrophila can help develop efficient strategies against Aeromonas infection. Herein, we investigated the temporal influence of A. hydrophila on the Chinese soft-shelled turtle, an economically important species, at the biochemical, transcriptomic, and metabolomic levels. Plasma parameters were detected with the test kits. Transcriptome and metabolome were respectively applied to screen the differentially expressed genes and metabolites. The contents or activities of these plasma parameters were significantly increased at 24 hpi and declined at 96 hpi, indicating that 24 and 96 hpi were two important time points during infection. Totals of 3121 and 274 differentially expressed genes (DEGs) from the transcriptome while 74 and 91 differentially abundant metabolites (DAMs) from the metabolome were detected at 24 and 96 hpi. The top DEGs at 24 hpi included Ccl2, Ccl3, Ccl4, Il1β, Il6, Il7, Il15, Tnf, and Tnfr1 while Zap70, Cd3g, Cd8a, Itk, Pik3r3, Cd247, Malt1, and Cd4 were the most abundant at 96 hpi. The predominant DAMs included O-phospho-L-serine, γ-Aminobutyric acid, orotate, L-tyrosine, and L-tryptophan at 24 hpi, as well as L-glutamic acid, L-arginine, glutathione, glutathione disulfide, and citric acid at 96 hpi. The combined analysis of DEGs and DAMs revealed that tryptophan metabolism, nicotinate and nicotinamide metabolism, as well as starch and sucrose metabolism, were the most important signaling pathways at the early infective stage while tyrosine metabolism, pyrimidine metabolism, as well as alanine, aspartate and glutamate metabolism were the most crucial pathways at the later stage. In general, our results indicated that the Chinese soft-shelled turtle displays stage-specific physiological responses to resist A. hydrophila infection.

Metabolomics and microbiome co-analysis reveals altered innate immune responses in Charybdis japonica following Aeromonas hydrophila infection

A comprehensive bioinformatics analysis was conducted to elucidate the innate immune response of Charybdis japonica following exposure to Aeromonas hydrophila. This study integrated metabolomics, 16S rRNA sequencing, and enzymatic activity data to dissect the immune mechanisms activated in response to infection. Infection with A. hydrophila resulted in an increased abundance of beneficial intestinal genera such as Photobacterium spp., Rhodobacter spp., Polaribacter spp., Psychrilyobacter spp., and Mesoflavibacter spp. These probiotics appear to suppress A. hydrophila colonization by competitively dominating the intestinal microbiota. Key metabolic pathways affected included fatty acid biosynthesis, galactose metabolism, and nitrogen metabolism, highlighting their role in the crab's intestinal response. Enzymatic analysis revealed a decrease in activities of hexokinase, phosphofructokinase, and pyruvate kinase, which are essential for energy homeostasis and ATP production necessary for stress responses. Additionally, reductions were observed in the activities of acetyl-CoA carboxylase and fatty acid synthase. Gene expression analysis showed downregulation in Peroxiredoxin 1 (PRDX1), Peroxiredoxin 2 (PRDX2), glutathione-S-transferase (GST), catalase (CAT), and glutathione (GSH), with concurrent increases in malondialdehyde (MDA) levels, indicating severe oxidative stress. This study provides insights into the molecular strategies employed by marine crabs to counteract bacterial invasions in their natural habitat.

Blunt snout bream (Megalobrama amblycephala) circARHGEF15 enhances antibacterial immunity against Aeromonas hydrophila infection via ceRNA regulatory axis

Circular RNAs (circRNAs) can be used as therapeutic targets for various human diseases through competitive endogenous RNA (ceRNA). Earlier research in our laboratory has revealed that circRNAs could serve as ceRNA to sponge microRNAs (miRNAs) and regulate the innate immune response of blunt snout bream (Megalobrama amblycephala) after Aeromonas hydrophila infection, but the specific regulation is still uncertain. In this research, by means of overexpression/RNAi, qPCR, and luciferase assay etc., we discovered a circRNA termed circARHGEF15, which was upregulated following A. hydrophila challenge and positively regulated antibacterial immunity in the host. Moreover, we observed that miR-214 can restore the promotion of inflammatory factors due to circARHGEF15 overexpression. Further, our data indicated that circARHGEF15 may function as a ceRNA of miR-214 in the immune reaction generated by A. hydrophila, reduce the inhibition of miR-214 on hepcidin, and promote the expression of downstream proinflammatory factors such as il-1β, il-6, il-8, and tnf-α. In summary, the results of this study suggest that M. amblycephala circARHGEF15 acts a significant function in the modulation of antibacterial response to A. hydrophila infection, and lays the foundation for rapid diagnosis, effective control, and treatment of fish diseases from the perspective of circRNAs in the future.

A novel antimicrobial peptide Spasin141-165 identified from Scylla paramamosain exhibiting protection against Aeromonas hydrophila infection

Aeromonas hydrophila is a widely distributed Gram-negative waterborne pathogen responsible for large-scale outbreaks of hemorrhagic septicemia in fish, causing severe economic losses to the global aquaculture industry. In view of few therapeutic drugs currently available for use in aquaculture and the emergence of multidrug-resistant A. hydrophila, there is an urgent need to develop new antimicrobial agents as an alternative to antibiotics. Antimicrobial peptides (AMPs) have strong antimicrobial effects and unique machanisms of action, and are not easy to induce bacterial resistance, making them an ideal alternative to antibiotics. In this study, we identified a new functional gene from marine crab Scylla paramamosain, named Spasin, which encodes a mature peptide of 240 amino acids and expressed widely in various tissues of crabs. Notably, a truncated peptide Spasin141–165 derived from Spasin, showed potent and broad-spectrum antibacterial and antifungal activity at minimum inhibitory concentrations (MICs) ranged from 0.75 μM–48 μM, which is a novel AMP. It effectively killed S. aureus and A. baumannii within 2 h and 90 min, respectively. Importantly, it is not toxic to HEK-293 T, RAW 264.7, and ZF4 cell lines. Mechanistic studies showed that addition of 8 μg mL−1 lipoteichoic acid or lipopolysaccharides decreased bacterial susceptibility to Spasin141–165. In addition, Spasin141–165 altered the permeability of the inner and outer cell membranes, and resulted in the release of ATP and the accumulation of intracellular reactive oxygen species. Notably, Spasin141–165 significantly increased the survival rate of zebrafish infected with A. hydrophila, redcued the bacterial load in the spleen, and effectively inhibited the expression of inflammation-associated factors (e.g., IL-1β, TNF-α, etc.). Taken together, Spasin141–165 is a potential antibacterial agent for the treatment of A. hydrophila infections in aquaculture and a promising antibiotic alternative.

Oral feed-based administration of phage cocktail protects rohu fish (Labeo rohita) against Aeromonas hydrophila infection.

Aeromonas hydrophila is one of the major freshwater fish pathogens. In the current study, a cocktail of D6 and CF7 phages was given orally to Labeo rohita to assess phage survival in fish organs as well as to determine the therapeutic efficacy of phage treatment against fish mortality caused by A. hydrophila. In the phage-coated feed, prepared by simple spraying method, phage counts were quite stable for up to 2 months with a decline of ≤ 0.23 log10 and ≤ 1.66 log10 PFU/g feed during 4 oC and room temperature storage. Throughout the experimental period of 7 days, both phages could be detected in the gut of fish fed with phage-coated feed. Besides, both CF7 and D6 phages were also detected in fish kidneys indicating the ability of both the phage to cross the intestinal barrier. During challenge studies with LD50 dose of A. hydrophila, phage cocktail doses of 1 × 106 - 1 × 108 PFU/g feed prevented the mortality in L. rohita with relative percentage survival (RPS) of 8.7-65.2. When challenged with LD90 dose of A. hydrophila, an RPS value of 28.6 was obtained at a phage cocktail dose of 1 × 108 PFU/g feed. The RPS data showed that orally-fed phage cocktail protected the fish against the mortality caused by A. hydrophila in a dose-dependent manner. Simple practical approaches for phage cocktail development, medicated feed preparation and oral administration along with phage survival and protection data make the current study useful for farmer-level application.

Fish arginase constrains excessive production of nitric oxide and limits mitochondrial damage during Aeromonas hydrophila infection

Bacteria-enhanced inducible nitric oxide synthase (iNOS) overproduces nitric oxide (NO) leading to mitochondrial and cellular damage. In mammals, arginase (ARG), the enzyme consuming the same substrate l-arginine with iNOS, was believed to inhibit iNOS activity by competing the substrate. But in fish, this conception has been widely challenged. In this study, the gene expression using real-time quantitative PCR (RT-qPCR) technology showed that when stimulated by Aeromonas hydrophila (A. hydrophila), grass carp (gc) iNOS was up-regulated in head kidney monocytes/macrophages (M0/MФ), and its changes were not detected in the whole tissue of liver or spleen, showing a high degree of cell-specific expression pattern. At the same time, gcARG2 had a high basal expression in tissues and was up-regulated by A. hydrophila stimulation. Next, phthalaldehyde-primaquine reaction was first used in the determination of intracellular urea in fish cells. It was found that the induced gcARG2 led to an increase in the intracellular urea content. Moreover, urea and NO production in M0/MФ were increased in a substrate dose-dependent manner from 30 to 100 μM of l-arginine and reached the highest yield at 300 and 3000 μM of l-arginine, respectively. Furthermore, head kidney M0/MФ was cultured in RPMI1640 medium containing physiological concentration (500 μM) of l-arginine to evaluate the effect of ARG. Under A. hydrophila stimulation, treatment with the arginase inhibitor S-(2-boronoethyl)-l-cysteine (BEC) showed that inhibition of arginase could further enhance the NO production stimulated by A. hydrophila. This in turn led to a cumulation in peroxynitrite (ONOO-) content and an injury of the mitochondrial membrane potential. Our study showed for the first time that fish ARG in head kidney M0/MФ can limit excessive production of NO and harmful products by iNOS to maintain mitochondrial and cellular homeostasis.

Effect of dietary Lagnaria breviflora leaves extract on the growth performance, haematological, antioxidativeand immune responses of African catfish (Clarias gariepinus) juveniles.

The effects of dietary Lagnaria breviflora leaves extract (LBLE) on the growth performance, feed utilisationand haematological parameters of juveniles African catfish, Clarias gariepinus (mean = 8.45 ± 0.6 g) raised in a flow water (mean temperature 26.7°C, mean pH 7.52, mean dissolved oxygen 6.05 mg/L) were assessed in this study. Diets (400 g/kg crude protein; 4631.5 kcal/kg gross energy) supplemented with LBLE at levels of 0 (control), 0.5, 1.0, 1.5or 2.0 g/kg diet were served to fish in triplicates (each replicate has 20 fish) until they appeared satiated for 12 weeks. Then, they were challenged with Aeromonas hydrophila infection for further 2weeks. Fish served dietary LBLE had considerable higher weight gain (64.76 g) and specific growth rate (765.5% g/day) than the fish group fed with the control diet with a reduced feed conversion ratio (1.45) (p < 0.05). Compared to fish fed with the control diet, the villi height (146.30 µm) and width (284.35 µm) of the intestines increased greatly in a dose (LBLE in diets) dependent order. Similarly, dietary LBLE increased (p < 0.05) the packed cell volume (46.11%) and haemoglobin (17.03 g/dL), whereas 1.5 g of LBLE increased the counts of white blood cells. Glutathione S-transferase (769.43 U/mg protein), glutathione peroxidase (84.14 U/mg protein)and superoxide dismutase (433.15 U/mg protein) activities were significantly higher (p < 0.05) in fish fed with diets supplemented with LBLE compared to the control one. Additionally, dietary LBLE increased phagocytic and lysozyme activities and protected C. gariepinus against bacterial infections where the lowest death was observed in the fish fed on the diet containing 1.5 g LBLE/kg feed. These findings showed that the fish fed with LBLE/kg diet improved their immune system, antioxidantand growth performance in addition to providing protection from A. hydrophila infection with the optimum dose of 1.80 g/kg diet.

Aeromonas hydrophila Infection following Leech Therapy for the Treatment of Nipple-Areola Complex Congestion after Breast Reduction: A Case Report.

Several strategies for the management of venous congestion of the nipple-areola complex (NAC) after reduction mammaplasty have been proposed. Among these, hirudotherapy represents an ancient but still effective method, even though the risk of infections related to leeches should be considered. We report a peculiar case of breast infection and sepsis after leech therapy in a patient who underwent a reduction mammaplasty. A prompt surgical debridement of the wounds and necrotic tissues associated with targeted antibiotic therapy led to a fast improvement of clinical conditions, and partial preservation of the NAC was obtained. Accurate knowledge of the clinical presentation of soft tissue infections related to leeching allows for an early diagnosis and would serve as a warning for surgeons who approach such breast cosmetic procedures.

Deciphering genome-wide molecular pathways for exogenous Aeromonas hydrophila infection in wide-bodied sand loach (Sinibotia reevesae)

Aquaculture, as a rapidly growing industry, plays a significant role in global food production and economic development. However, various infectious diseases, particularly those caused by the gram-negative bacterium Aeromonas hydrophila, pose a critical threat to the sustainability and productivity of world-wide aquaculture operations. Investigating the molecular mechanisms of A. hydrophila infection can help to identify key targets for therapeutic interventions and vaccines, thereby reducing economic losses associated with disease outbreaks. Our present study focuses on wide-bodied sand loach (WBSL, Sinibotia reevesae), a captive-bred commercial fish, to explore detailed molecular effects of exogenous A. hydrophila infection. Firstly, a high-quality chromosome-level haplotype genome with a total length of 774 Mb and 49 chromosomes was assembled, providing valuable insights into its genetic components. Secondly, we isolated and characterized a newfound A. hydrophila F4S strain, examined pathological symptoms of WBSL after infection, and then investigated dynamic gene expressions. Our results revealed that the bacterial infection decreased metabolic activity, causing disruptions in cardiac function, cellular homeostasis, tissue damages, and impaired energy utilization. The immune system responds multifaceted, potentially impacting overall health and survival. In summary, our findings contribute to the understanding of the complicated interactions between WBSL and exogenous A. hydrophila, especially shed lights on the genetic complexity, immune responses, and potential impacts on fish health and survival. Furthermore, this study provides new insights into the mechanisms underlying A. hydrophila infection, and offers potential strategies to offload corresponding pathological effects, not only in WBSL but also in other aquaculture species.

Investigating the impact of external application of formalin and potassium permanganate on hematological, immunological, and biochemical profiles in Labeo rohita fingerlings

The present study aimed to elucidate the suitability of formalin and KMnO4 as therapeutics for fish diseases in Indian major carp, Labeo rohita, while considering their impact on fish stress levels. Acute toxicity tests revealed that the 96-hour LC50 values for formalin and KMnO4 were 66.58 ppm and 2.89 ppm, respectively. Sub-lethal concentrations of formalin (6.65 ppm, 3.32 ppm, and 2.21 ppm) and KMnO4 (0.289 ppm, 0.145 ppm, and 0.096 ppm), along with control groups, were administered to the fish for different exposure periods (24, 48, 72, and 96 hours) and different hematological, biochemical, and immunological parameters were analyzed. The findings demonstrated that formalin exposure resulted in a significant decrease (p < 0.05) in hematological parameters, immunological parameters, and serum protein levels. Conversely, formalin exposure led to significant increases (p < 0.05) in serum glucose, SGOT, SGPT, and ALP levels. In contrast, KMnO4 exposure significantly decreased (p < 0.05) hematological parameters and serum protein levels, while significantly increasing (p < 0.05) immunological parameters. To evaluate curative efficacy, challenge studies were conducted using three sub-lethal concentrations of formalin and KMnO4 against Aeromonas hydrophila (ATCC 7966) infection. Based on the aforementioned results, the recommended doses of formalin and KMnO4 were found to be 6.65 ppm and 0.289 ppm, respectively.

MCSFR+ monocytes/macrophages are activated to produce IL-4/13 in the gill lamellae of grass carp after infection with bacterial pathogens

Macrophage colony-stimulating factor receptor (MCSFR) is a cell lineage marker for monocytes/macrophages and has been applied for cell typing in mammals. However, lack of high-quality monoclonal antibodies hampers isolation and functional characterization of monocytes/macrophages in fish. A monoclonal antibody (mAb) against the extracellular region of grass carp (Ctenopharyngodon idella, Ci) MCSFR using the recombinant protein produced in the E. coli cells was generated in this study. Western blotting showed the mAb could recognize the native CiMCSFR protein derived from tissues and the recombinant CiMCSFR protein expressed in the E. coli cells and HEK293 cells. The antibody did not cross-react with the MCSFR homolog in zebrafish, indicating that it has good species specificity. Immunofluorescence analysis showed MCSFR+ monocytes/macrophages distributed in the gills, hindgut, head kidney and spleen of healthy grass carp. Furthermore, Aeromonas hydrophila infection resulted in increased MCSFR+ monocytes/macrophages in the lamina propria and epithelium of hindgut mucosa. In addition, Flavobacterium columnare infection led to the infiltration of MCSFR+ monocytes/macrophages in the gills, and interestingly, the MCSFR+ monocytes/macrophages in the gill lamellae but not filaments are activated to produce IL-4/13A and IL-4/13B, while MCSFR+ monocytes/macrophages in the hindgut did not produce IL-4/13A and IL-4/13B. Our results indicate that monocytes/macrophages are participated in mediating mucosal immune responses to bacterial infections and will help understand host immune defense to bacterial diseases.

Supplementation of Bacillus subtilis and Lactobacillus casei to increase growth performance and immune system of catfish (Clarias gariepinus) due to Aeromonas hydrophila infection.

Catfish has a high economic value and is popular among consumers. To ensure well-stocked catfish stocks, good fisheries management must also be ensured. The high demand for catfish must be supplemented by preventive measures against pathogenic bacterial infections using probiotics with high potential for Lactobacillus casei and Bacillus subtilis. The aim of this study was to determine the effect of probiotic supplementation consisting of a combination of L. casei and B. subtilis probiotics on the growth, immune system, water quality, proximate value of feed, and body composition of catfish infected with Aeromonas hydrophila. This study used a completely randomized study with eight treatments and three replications. The manipulated factor was the probiotic concentration [0% (A), 0.5% (B), 10% (C), and 15% (D)] in groups of catfish infected and uninfected with A. hydrophila. Combination of B. subtilis, and L. casei that were used in a 1:1 ratio of 108 colony forming unit/mL. The study lasted for 42 days. On the 35th day, A. hydrophila was infected by intramuscular injection into fish. The Statistical Package for the Social Sciences (SPSS) software version 23.0 (IBM SPSS Statistics) was used to analyze data on growth, immune system, and water quality. Providing probiotics in feed can increase the nutritional value of feed based on proximate test results. There were significant differences in average daily gain (ADG), feed conversion ratio (FCR), and survival rate (SR) parameters in the group of catfish infected with A. hydrophila (p > 0.05); however, there were no significant differences in final body weight, specific growth rate (SGR), and percentage weight gain. Interleukin-1β (IL-1β) levels were significantly different between treatments C and D. The tumor necrosis factor (TNF) α parameters were significantly different between treatments A and C, whereas the phagocytic activity of treatment A was significantly different from that of treatment D. There was a significant difference (p > 0.05) in the growth parameters of SGR, ADG, and FCR in the group of fish that were not infected with A. hydrophila, with the best treatment being a probiotic concentration of 15%, but there was no significant difference in the SR parameters. IL-1β and TNF-α levels significantly differed between E and E0 (15% probiotics) but were not significantly different in terms of phagocytosis parameters. Based on the results of this study, it can be concluded that using a combination of probiotics L. casei and B. subtilis can improve the growth, immune system, water quality, proximate value of feed, and body composition of catfish infected with A. hydrophila.

High replacement of soybean meal by different types of rapeseed meal is detrimental to rainbow trout (Oncorhynchus mykiss) growth, antioxidant capacity, non-specific immunity and Aeromonas hydrophila tolerance.

A 12-week feeding trial was conducted to evaluate the effects of replacing soybean meal with different types of rapeseed meal (RSM; Chinese 95-type (oil press model) rapeseed meal [C95RM], Chinese 200-type rapeseed meal [C200RM], cold pressed rapeseed cake [CPRC], Indian rapeseed meal [IRM] and Canadian rapeseed meal [CRM]) on growth, antioxidant capacity, non-specific immunity and Aeromonas hydrophila infection tolerance in 990 fingering (average weight 12.77 ± 0.01 g) rainbow trout (Oncorhynchus mykiss). A basal diet was prepared using fishmeal and soybean meal as the main protein sources, the other 10 diets were formulated with five types of RSM at 20% (C95RM20, C200RM20, CPRC20, IRM20, CRM20) or 35% (C95RM35, C200RM35, CPRC35, IRM35, CRM35) inclusion levels to replace iso-nitrogenous soybean meal. Regardless of the RSM source, dietary inclusion of 20% RSM significantly reduced the weight gain rate (WGR) and digestive enzymes activities (except C200RM20) of fish, but increased the blood urea nitrogen (BUN) and hepatic malondialdehyde (MDA) content (except CRM20). Fish fed with CPRC20 and IRM20 exhibited relatively higher plasma cortisol and MDA content, but lower content/activities of triiodothyronine (T3), thyroxine (T4) and glutathione peroxidase (GPx) in plasma, lysozyme (LZM) and complement 3 (C3) in serum, catalase (CAT) in liver, and respiratory burst activity (RBA) of head kidney macrophages. The intestinal and hepatic tissues fed with 20% RSM were damaged to some extent, with the CPRC20 and IRM20 groups being the most severely affected. Regardless of the RSM source, dietary inclusion of 35% RSM significantly decreased WGR and digestive enzymes activities, but significantly increased plasma BUN and MDA content. The fish fed with CPRC35 and IRM35 exhibited relatively higher plasma cortisol, MDA, serum triglyceride, BUN content, but lower content/activities of T3, T4, C3, and LZM in serum, CAT, peroxidase and GPx in plasma, CAT in liver, RBA and phagocytic activity of head kidney macrophage. The hepatic and intestinal tissues damage was the worst in the IRM35 group among the 35% RSM inclusion groups. These results indicate that including ≥20% RSM in the diet, regardless of the source, reduced the growth, antioxidant capacity, immunity, and survival to Aeromonas hydrophila infection in rainbow trout.

Genomic and transcriptome insight into the structure and immunity role of TRIM proteins in Chinese soft-shelled turtles (Pelodiscus sinensis) after Aeromonas hydrophila infection.

TRIM proteins, recognized as a class of E3 ubiquitin ligases, are increasingly acknowledged for their antipathogen immune functions in mammals and fish. In the Chinese soft-shelled turtle (Pelodiscus sinensis), a secondary aquatic reptile that occupies a unique evolutionary position, the TRIM gene has rarely been reported. In the present study, 48 PsTRIM proteins were identified from the genome of Pelodiscus sinensis via Hidden Markov Model (HMM) searches and Signal Transduction ATPases with Numerous Domains (SMART) analysis. These PsTRIMs were found across 43 distinct scaffolds, and phylogenetic analyses classified them into three principal clades. The PsTRIMs feature a conserved assembly of either RING-B-box-coiled-coil (RBCC) or B-box-coiled-coil (BBC) domains at the N-terminus, in addition to eight unique domains at the C-terminus, including the B30.2 domain, 19 of which were identified. Expression profiling revealed ubiquitous expression of the 48 PsTRIMs across various P. sinensis tissues. Notably, seven PsTRIMs exhibited significant differential expression in liver transcriptomes following infection with Aeromonas hydrophila. Weighted gene coexpression network analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis implicated PsTRIM14 and PsTRIM28 as key players in host defense against bacterial invasion. Real-time quantitative PCR results indicated that PsTRIM1, PsTRIM2, PsTRIM14, and PsTRIM28 experienced marked upregulation in P. sinensis livers at 12h post-infection with A. hydrophila. Our study is the first to comprehensively identify and analyze the functions of TRIM genes in P. sinensis, unveiling their considerable diversity and potential roles in modulating immune responses.

The identification of a serpin with immune defense role in oriental river prawn Macrobrachium nipponense

Serpins are a protein superfamily of serine protease inhibitors. One of their functions is to participate in immune responses by inhibiting the activation of prophenoloxidase. To elucidate the immune role of serpin in Macrobrachium nipponense, a serpin gene (Mnserpin) was cloned from M. nipponense in this study. Mnserpin protein has an N-terminal signal peptide and a serpin domain that contains a hinge region, a signature sequence of serpin and a P1(arginine)-P1’ scissile bond, and evolutionally closely related to the crustacean serpins. Mnserpin highly expressed in the hepatopancreas and gill. Mnserpin expression increased first and then decreased after Vibrio parahaemolyticus and Aeromonas hydrophila infection, and was knocked down by dsMnserpin injection with a maximum knockdown efficiency of 92 %. Mnserpin knockdown increased the expression of the clip domain serine protease and prophenoloxidase genes and phenoloxidase activity of M. nipponense as well as its mortality rate after V. parahaemolyticus and A. hydrophila infection. The recombinant Mnserpin (rMnserpin) showed bacteria-binding and bacteriostatic activity in vitro. Moreover, rMnserpin injection decreased the bacterial number and the mortality rate of M. nipponense post V. parahaemolyticus and A. hydrophila infection. These results suggested that Mnserpin plays a major role in the innate immune response of M. nipponense.

Chicken egg lysozyme enhanced the growth performance, feed utilization, upregulated immune-related genes, and mitigated the impacts of Aeromonas hydrophila infection in Nile tilapia (Oreochromisniloticus)

Functional supplements, including lysozyme, are highly approved as immunostimulant and antibacterial agents with a high potential for use in aquaculture. In this regard, Nile tilapia was treated with lysozyme at 0, 0.5, 1, 1.5, and 3 g/kg for 60 days, then challenged with Aeromonas hydrophila. Fish were stocked in 15 glass aquaria (70 L each) with an equal initial weight of 10.72 ± 0.71 g per fish and 15 fish per aquarium. The regression analysis revealed that dietary lysozyme supplementation at 1.83–2 g/kg enhanced the growth performance, protein efficiency ratio, and protein productive value while reducing the feed conversion ratio of tilapia. Markedly, tilapia treated with lysozyme had a low mortality rate (30–50 %) compared to the control, which recorded a 70 % mortality rate after 15 days of challenge with A. hydrophila. The regression analysis also revealed that the highest lysozyme activity of tilapia-fed lysozyme for 60 days is achieved by 2.05 g/kg lysozyme. The expression of Nf-κb, IL-1β, and IL-8 genes is upregulated in tilapia-fed lysozyme at 0.5, 1, 1.5, and 3 g/kg for 60 days before and after A. hydrophila infection. The expression of GPX and CAT genes was higher in tilapia-fed lysozyme at 0.5, 1, 1.5, and 3 g/kg for 60 days before and after A. hydrophila infection. Before infection, the relative transcription of the lysozyme and C3 was upregulated in tilapia-fed lysozyme at 0.5, 1, 1.5, and 3 g/kg. However, lysozyme gene expression in tilapia treated with 0.5 g/kg lysozyme had no significant differences from those fed 0 g/kg lysozyme. After infection, the relative transcription of the lysozyme gene was upregulated in tilapia fed 1 and 1.5 g/kg, while tilapia fed 1 g/kg lysozyme had the highest C3 gene transcription. After infection, the hepatocytes in the livers of fish fed 0 g/kg lysozyme exhibited a noticeable fatty alteration, along with congestion, a light infiltration of inflammatory cells, and the start of necrosed cell regeneration. However, the livers of fish that received lysozyme were normal except for infiltrations of perivascular and interstitial mononuclear cells, depending on the supplementation dose. In conclusion, dietary lysozyme is recommended at 1.83–2.05 g/kg to gain high growth performance, immune response, and high resistance to A. hydrophila in Nile tilapia.

Effect of Stocking Density and Diets Supplemented with Essential oils and or Probiotic on the Performance of Juveniles Nile tilapia (Oreochromis niloticus)

The present study was carried out to investigate the interactive effect of stocking density and diets supplemented with essential oils and or probiotic on the growth performance of juveniles Nile tilapia (Oreochromis niloticus), water quality parameters, intestinal morphology, and protection against Aeromonas hydrophila infection of Oreochromis niloticus. Total number of 640 O. niloticus fish (14.2 ± 0.95 g) were used in our work were allotted into eight groups with three replicates with two stocking densities (36 fish m-3 and 72 fish m-3) and four diets (control, Probiotic (Sanolife PRO-F®), Essential oils (EOs) blend (Super Immune®) and mix of Probiotic (Sanolife PRO-F®) and EOs blend (Super Immune®) respectively for 14 weeks and subsequently, challenged with A. hydrophila. The fish raised at the low stocking density exhibited increased weight gain, feed intake and specific growth rate compared with those raised at the high stocking density. Probiotic and/or EOs blend dietary supplementation improved Nile tilapia weight gain, daily gain, specific growth rate, total feed intake and feed conversion ratio. The water quality metrics' readings throughout the experiment all stayed within acceptable ranges for tilapia production despite the density increase. The fish raised at the low stocking density and received diet supplemented with mix of probiotic and EOs showed marked increased length of intestinal villi compared with the other groups. The EOs blend promoted better relative percent of survival with percentage of 100 % after challenge by A. hydrophila. It could be concluded that using EOs blend (Super Immune) and/or Probiotic (Sanolife PRO-F) as a dietary supplement for tilapia fingerlings would be a good choice due to their effective growth promoting, antibacterial effect and their positive impacts on fish intestinal morphology.

Activity of Natural Compound Pothos tener Wall on Aeromonas hydrophila Infection to Prevent of Antibiotics

This study aims to discover how influential Photos tener Wall is as an anti-bacterial treatment for Aeromonas hydrophila. Methods: Cyprinus Carpio were reared for 28 days, and on the 29th and 30th days before Aeromonas hydrophila infection, the fish were adequately fasted. On the 31st day, they were intramuscularly challenged with A. hydrophila (105 CFU/mL) (the first day in A. hydrophila infection). The treatments given were (I) immersed trial with fresh (live) P tener Wall: (H1) Immersed with 15 g of P. tener Wall plant, (H2) Immersed with 30 g of P. tener Wall plant, and (H3) Immersed with 60 g of P. tener; (II) feeding trials in which the treatments given were (P1) 2% of P. tener Wall powder mixed with 1 kg commercial diet and (P2) 4% of P. tener Wall powder mixed with 1 kg commercial diet; Experiment III combined the best results from experiment I (H2) and experiment II (P2) and Oxytetracycline 5 g/kg feed as a control antibiotic. The result obtained was that the treatment of 30 g of fresh P. tener Wall or adding 4% simplicial P. tener Wall in the diet could increase koi fish's immune response and resistance to A. Hydrophila has a survival rate that reaches 100%. This treatment has the same effect as using antibiotic Oxytetracycline 5 g/kg of feed. An important aspect for further research is that P. tener wall can be tested on other fish diseases caused by bacteria or fungi.

Activity of Natural Compound Pothos tener Wall on Aeromonas hydrophila Infection to Prevent of Antibiotics

This study aims to discover how influential Photos tener Wall is as an anti-bacterial treatment for Aeromonas hydrophila. Methods: Cyprinus Carpio were reared for 28 days, and on the 29th and 30th days before Aeromonas hydrophila infection, the fish were adequately fasted. On the 31st day, they were intramuscularly challenged with A. hydrophila (105 CFU/mL) (the first day in A. hydrophila infection). The treatments given were (I) immersed trial with fresh (live) P tener Wall: (H1) Immersed with 15 g of P. tener Wall plant, (H2) Immersed with 30 g of P. tener Wall plant, and (H3) Immersed with 60 g of P. tener; (II) feeding trials in which the treatments given were (P1) 2% of P. tener Wall powder mixed with 1 kg commercial diet and (P2) 4% of P. tener Wall powder mixed with 1 kg commercial diet; Experiment III combined the best results from experiment I (H2) and experiment II (P2) and Oxytetracycline 5 g/kg feed as a control antibiotic. The result obtained was that the treatment of 30 g of fresh P. tener Wall or adding 4% simplicial P. tener Wall in the diet could increase koi fish's immune response and resistance to A. Hydrophila has a survival rate that reaches 100%. This treatment has the same effect as using antibiotic Oxytetracycline 5 g/kg of feed. An important aspect for further research is that P. tener wall can be tested on other fish diseases caused by bacteria or fungi.

Paraprobiotic supplementation to fish feed: effects on the immune support system and control of Aeromonas hydrophila infection in Labeo rohita

Paraprobiotic supplementation to fish feed: effects on the immune support system and control of Aeromonas hydrophila infection in Labeo rohita