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1.
Adenosine deaminase (ADA) activity, through adenosine (Ado) levels, as well as xanthine oxidase (XO) activity through uric acid levels exerts an essential role on immune and inflammatory responses during infectious diseases. Thus, the aim of this study was to evaluate the involvement of seric ADA and XO activities in the inflammatory and oxidative status of silver catfish naturally infected with Ichthyophthirius multifiliis. Seric ADA activity decreased, while Ado levels increased in infected animals compared to uninfected animals. Moreover, the seric XO activity increased in infected animals compared to uninfected animals, alongside the seric levels of uric acid, metabolites of nitric oxide (NOx) and reactive oxygen species (ROS). Based on this evidence, the downregulation of seric ADA activity exerts an anti‐inflammatory profile, contributing to restricting the inflammatory process. The most important finding is that upregulation of seric XO activity leads to an excessive formation of uric acid, which contributes to oxidative and inflammatory processes. Moreover, uric acid induces the release of pro‐inflammatory and pro‐oxidative mediators, such NOx and ROS, which contribute directly to disease pathogenesis. In summary, the upregulation of XO activity may be considered a pathway involved in NOx and ROS production in silver catfish infected with I. multifiliis.  相似文献   

2.
Extracellular adenosine triphosphate (ATP) and its metabolite adenosine (Ado) are recognized as key mediators of immune and inflammatory responses. Depending on its concentration, ATP may act as an immunostimulant or immunodepressant, while Ado levels display an anti‐inflammatory profile. The aim of this study was to evaluate whether splenic purinergic signalling is capable of modulating immune and inflammatory responses in fish experimentally infected with Aeromonas caviae. Triphosphate diphosphohydrolase (NTPDase) and 5′‐nucleotidase activities increased in the spleen of silver catfish (Rhamdia quelen) experimentally infected with A. caviae compared with the uninfected control group. Moreover, splenic Ado levels increased in the infected animals relative to the uninfected control group. Based on these lines of evidence, our findings revealed that adenine nucleotide hydrolysis is modified in the spleen of fish infected with A. caviae attempting to restrict the inflammatory process through the upregulation of NTPDase and 5′‐nucleotidase activities, which occurs in an attempt to hydrolyse the excessive ATP in the extracellular environment and rapidly hydrolyse AMP to form Ado. In summary, purinergic signalling can modulate immune and inflammatory responses during A. caviae infection.  相似文献   

3.
Streptococcus agalactiae causes a severe systemic disease in fish, and the routes of entry are still ill‐defined. To address this issue, two groups of 33 red tilapia Oreochromis spp. each of 10 g were orally infected with S. agalactiae (n = 30), and by immersion (n = 30), six individuals were control‐uninfected fish. Three tilapias were killed at each time point from 30 min to 96 h post‐inoculation (pi); controls were killed at 96 h. Samples from most tissues were examined by haematoxylin–eosin (H&E), indirect immunoperoxidase (IPI) and periodic acid‐Schiff; only intestine from fish infected by gavage was evaluated by transmission electron microscopy. The results of both experiments suggest that the main entry site of S. agalactiae in tilapia is the gastrointestinal epithelium; mucus seems to play an important defensive role, and environmental conditions may be an important predisposing factor for the infection.  相似文献   

4.
Immunopathological and ultrastructural studies were carried out on the gills of bream, Abramis brama, naturally infected with the copepod Ergasilus sieboldi and on the intestine of brown trout, Salmo trutta, infected with the acanthocephalan Echinorhynchus truttae. Infected gills showed extensive tissue damage due to copepod attachment, including hyperplasia, as well as proliferation of mast cells, rodlet cells and mucous cells. In parasitized gills of bream, mast cells were more abundant than in uninfected gills. They were free within the lacunae, as well as outside and inside the blood vessels of the primary lamellae, and made intimate contact with vascular endothelial cells and with neutrophils. In some infected gills, degranulation of mast cells was common. Infected intestines of brown trout had more mast cells than uninfected intestines, and these cells were often in close proximity to, and inside, the capillaries and lying close to fibroblasts of the muscularis layer and stratum granulosum. Intense degranulation of mast cells was encountered in all intestinal layers, especially near the E. truttae body.  相似文献   

5.
The activity of acetylcholine (ACh) synthesizing enzyme, choline acetyltransferase (ChAT), and the content of ACh were determined in the brain, heart, red trunk muscle and midgut of 12 freshwater teleost species belonging to eight families: carp (Cyprinus carpio), tench (Tinca tinca), silver carp (Hypophthalmichtys molitrix), bighead (Hypophthalmichtys nobilis), wels (Silurus glanis), cat fish (Ictalurus nebulosus), eel (Anguilla anguilla), rainbow trout (Oncorhynchus mykiss), pike (Esox lucius), pike-perch (Stizosteidon lucioperca), ruffe (Acerina cernua) and pumpkinseed (Lepomis gibbosus). The rate of ACh degradation in the same tissues was characterized by measuring the activity of acetylcholinesterase (AChE). Comparisons by statistical evaluation of cholinergic parameters in the corresponding organs were made between the species or families. The highest ACh concentration was found in the brain (between 9.6 and 16.0 nmol/g), and the gut (4.6 to 17.4 nmol/g), followed by the heart (1.4 to 3.9 nmol/g) and trunk muscle (1.2 to 3.8 nmol/g). Good correlations were found between the ACh content and the ChAT activity in all the organs studied. The correlation coefficients were 0.92 and 0.72 for the brain and heart, respectively. The activity of ChAT and the amount of ACh found in the brain and trunk muscle varied considerably from one family to another, but was of comparable degree within one family. It was concluded that differences in the cholinergic parameters may reflect different feeding and swimming behavioral patterns.  相似文献   

6.
Nile tilapia (Oreochromis niloticus) farming is an economic activity that is soaring in the whole world. Septicemia due to Streptococcus agalactiae is the main disease impacting fish farming. The aim of this study was to compare the gut microbiome of healthy animals and animals experimentally infected with S. agalactiae strain 21171A. The microbiome was established with 16S ribosomal DNA next‐generation sequencing (NGS). One hundred Nile tilapias, with an average weight of 35 g, were distributed into two groups. Fifty fish from the challenged group were orally inoculated with 100 μl of a bacterial solution containing 1.98 × 103 CFU/ml of S. agalactiae strain 21171A, while 50 controls were orally inoculated with sterile saline. After the experiment, 24 fish from the challenged group and 27 fish from the control group were analysed. For both groups, bacteria attached to the mucosa (M) and present in faeces (F) were analysed. The mean of the number of taxa identified in the infected group (M + F) (45.87 ± 30.13) was lower than in the control (M + F) (67.70 ± 21.10) (p < .01). Nineteen bacterial taxa were more abundant in faecal samples from the infected group when compared with the control group (p < .01). Thirty‐nine taxa were associated with mucosa samples from the challenged group when compared to the control samples (p < .01). No OTU was associated with healthy samples. The results demonstrate that the infection with S. agalactiae reduces the variability of the gut microbiota. Moreover, some bacteria proliferate during the infection.  相似文献   

7.
Streptococcus agalactiae is one of the major causative agents of tilapia streptococcosis, which has caused severe economic losses in aquaculture. Rapid and accurate detection of the pathogen is necessary to limit losses because of this disease. In this study, a loop‐mediated isothermal amplification (LAMP) assay was developed for the detection of S. agalactiae. Firstly, a set of four primers was designed to target the cfb gene of S. agalactiae. Then, using Bst DNA polymerase, the LAMP assay was performed at 65 C for 60 min and terminated at 80 C for 10 min in a simple water bath. Positive or negative results could be observed by direct visual inspection. There were no cross reactions with other bacterial species, indicating high specificity of the LAMP assay. The sensitivity of the LAMP assay for detecting S. agalactiae was about 20 cells per reaction. Moreover, the developed closed‐tube step has greatly improved the LAMP system. The LAMP method was also applied to detect S. agalactiae in infected tilapia tissue, demonstrating usefulness in diagnostics. Overall, this study showed that the cfb‐based LAMP assay was an effective method to detect S. agalactiae rapidly.  相似文献   

8.
刘灵  徐俊  马盼  李安兴 《水产学报》2019,43(5):1308-1316
实验采用BALB/c小鼠作为实验动物,旨在建立尼罗罗非鱼无乳链球菌毒力测定的BALB/c小鼠模型。BALB/c小鼠经腹腔注射尼罗罗非鱼源无乳链球菌建立感染模型,比较了尼罗罗非鱼源无乳链球菌分别感染尼罗罗非鱼和小鼠的LD_(50)差异,分别测定了不同毒力尼罗罗非鱼无乳链球菌对尼罗罗非鱼和小鼠的毒力。结果显示,小鼠经腹腔注射无乳链球菌,在24 h内出现死亡现象,且对小鼠脑、肝脏、脾脏、肾脏等组织造成损伤。3次测定尼罗罗非鱼无乳链球菌TFJ0901对尼罗罗非鱼和小鼠LD_(50)分别为7.7×10~7、2.2×10~8、3.5×10~9 CFU/mL和405、361、419 CFU/只。将无乳链球菌TFJ0901和THN0901感染尼罗罗非鱼(1.0×10~7 CFU/mL)和小鼠(100 CFU/只),尼罗罗非鱼和小鼠存活率分别为100%、6.7%±5.8%和100%、0,其存活率都具有显著性差异。将无乳链球菌TFJ0901和TFJ-F感染尼罗罗非鱼(3.0×10~8 CFU/mL)和小鼠(2 500 CFU/只),尼罗罗非鱼的存活率分别为73.3%±11.5%和80.0%±10.0%,存活率差异不显著,小鼠存活率分别为13.3%±11.5%和100.0%,存活率具有显著性差异。研究表明,本实验成功建立了BALB/c小鼠作为尼罗罗非鱼源无乳链球菌毒力测定的稳定模型,测定不同毒力的尼罗罗非鱼源无乳链球菌对小鼠毒力与对尼罗罗非鱼毒力一致,且该模型能够区分尼罗罗非鱼模型难以区分的毒力相近的无乳链球菌。  相似文献   

9.
The study was undertaken to determine the modulation in innate immune response of rohu (Labeo rohita) during experimental freshwater lice Argulus siamensis infection. Results showed that serum α‐2 macroglobulin (α‐2M) activity, ceruloplasmin level and alternative complement activity were significantly (P<0.05) lower in fish at different degrees of lice infection in comparison with uninfected control. No significant difference (P>0.05) in haemagglutination titre was observed in fish with low‐ and high‐degree lice infections as compared with uninfected control. The serum lysozyme level was significantly (P<0.05) lower in low degree of lice infection as compared with control fish. The total serum antiprotease, myeloperoxidase activity and total protein level were not significantly different (P>0.05) in different degrees of lice‐infected fish with respect to the control fish. The study indicated that A. siamensis infection modulated the immune system of rohu by suppressing the α‐2M, serum complement activities and ceruloplasmin level and through induction of stress response. The baseline data obtained in the present study have tremendous importance in understanding the susceptibility of rohu to different degrees of parasitosis and might be useful in controlling this dreaded ectoparasitic infection in fish.  相似文献   

10.
During a PCR‐based CEV survey in Poland in 2015–2017, the virus was detected in many farms both in clinical and asymptomatic cases and in common as well as in koi carp (Cyprinus carpio). In order to evaluate the potential carrier role of fish species that share the same habitats with carp, an experimental trial was performed. Investigations carried out on specimens of bleak (Alburnus alburnus), crucian carp (Carassius carassius), European perch (Perca fluviatilis), Prussian carp (Carassius gibelio), roach (Rutilus rutilus) and tench (Tinca tinca) cohabited with CEV‐infected carp yielded positive results. These species of fish were experimentally cohabited with CEV‐infected common carp at a temperature of 16°C ± 1. Material from the brain, gills, spleen, kidneys, intestine and skin was investigated for the presence of CEV DNA. Similar investigations were performed with uninfected fish designated controls. Samples were tested for CEV by qPCR.  相似文献   

11.
Streptococcosis, lactococcosis and enterococcosis are among the most important bacterial diseases affecting tilapia farms in Kafr Elsheikh governorate, Egypt. A number of clinically diseased fish were collected and submitted to our laboratory during disease outbreak in 2018. They were characterized by nervous swimming behaviour, skin darkness, exophthalmia, ocular opacity and haemorrhages. Necropsy findings were splenomegaly, congestive hepatomegaly, liquefied brain and enteritis. The phenotypic and molecular characterizations of the bacterial strains isolated from naturally infected fish identified three genera of Gram‐positive cocci: Streptococcus agalactiae, Enterococcus faecalis and Lactococcus garvieae. Infectivity trials were conducted in four groups of Nile tilapia inoculated with S. agalactiae Egy‐1, E. faecalis Egy‐1 and L. garvieae Egy‐1 strains and saline. Mortalities, clinical signs and pathological findings were recorded daily 14 days post infection. Experimentally infected tilapia showed similar clinical signs, postmortem lesions, but varied in the severity and experienced high mortalities up to 70% in case of S. agalactiae and L. garvieae infections and 30% in case of E. faecalis infection. Pathological examination of infected tissue sections stained with modified Brown–Brenn and immunohistochemistry revealed an important direct correlation between the distribution of each bacterial isolate and the lesions developed in different organs. Furthermore, the isolates were subjected to profiling against 11 antibiotics, and they showed resistance against several types of antibiotics, which implicate potential risk to human health and emphasize the urgent need for alternate bio‐control strategies to prevent the diseases and the problem of multidrug resistance in aquatic environment.  相似文献   

12.
Streptococcus agalactiae has become one of the most important emerging pathogens in the aquaculture industry and has resulted in large economic losses for tilapia farms in China. In this study, three pairs of specific primers were designed and tested for their specificities and sensitivities in quantitative real‐time polymerase chain reactions (qPCRs) after optimization of the annealing temperature. The primer pair IGS‐s/IGS‐a, which targets the 16S‐23S rRNA intergenic spacer region, was finally chosen, having a detection limit of 8.6 copies of S. agalactiae DNA in a 20 μL reaction mixture. Bacterial tissue tropism was demonstrated by qPCR in Oreochromis niloticus 5 days post‐injection with a virulent S. agalactiae strain. Bacterial loads were detected at the highest level in brain, followed by moderately high levels in kidney, heart, spleen, intestines, and eye. Significantly lower bacterial loads were observed in muscle, gill and liver. In addition, significantly lower bacterial loads were observed in the brain of convalescent O. niloticus 14 days post‐injection with several different S. agalactiae strains. The qPCR for the detection of S. agalactiae developed in this study provides a quantitative tool for investigating bacterial tissue tropism in infected fish, as well as for monitoring bacterial colonization in convalescent fish.  相似文献   

13.
Attempts were made to identify the association between water quality parameters and the presence of Streptococcus agalactiae in cage cultured red hybrid tilapia, Oreochromis niloticus × O. mossambicus. Fish from commercial floating net cage‐culture systems in a river and lake were randomly sampled over a 24‐month period. Swabs from the brains, eyes and kidneys were streaked directly onto blood agar to isolate S. agalactiae. Water temperature, dissolved oxygen, pH, clarity, ammonia, nitrite, sulfide, rate of water flow and depth of water at sampling sites were measured at the same time of fish sampling. The prevalence of fish that were cultured positive to S. agalactiae was significantly higher in lake compared with river. The length and weight of the infected fish were between 9 and 33 cm, and between 20 and 760 g respectively. There was a significant and positive strong correlation between the presence of S. agalactiae and fish mortalities in lake. All water quality parameters showed significant differences between river and lake. However, only water temperature, clarity and pH of lake and the ammonia, temperature and dissolved oxygen in river showed significant correlation with the presence of S. agalactiae in the cultured fish. It was concluded that several unfavourable water quality in the fish farm influencing the presence of S. agalactiae in cultured red hybrid tilapia.  相似文献   

14.
CD3 is an important membrane molecule of mature T cells. TCR‐CD3 complex plays important roles in the activation and signal transduction of T cells. In this study, the CD3ε (OnCD3ε) gene was cloned from Nile tilapia (Oreochromis niloticus), and its tissue distribution was detected by qPCR. The expression changes in CD3ε were analysed after three challenges (S. agalactiae, A. hydrophila and poly (I:C)) in vivo and in vitro. The open reading frame (ORF) of OnCD3ε contains 531 bp, encoding 176 amino acids, which found that OnCD3ε consists of conserved amino acid residues and motifs (cysteine residues, CXXC motif, immunoreceptor tyrosine‐based activation motifs and PxPDY). In addition, tissue distribution displayed that OnCD3ε has the highest expression in thymus and significant expression level in mucosal immune‐related tissues (intestine and gills). In vivo, all three challenges could significantly up‐regulate the expression of CD3ε in the head kidney and spleen. For further in vitro assays, after poly (I:C) stimulation, OnCD3ε appeared significant up‐regulation at 3 hr post stimulation, and two pathogenic bacteria also induce significant up‐regulation of OnCD3ε in spleen leucocytes (12 hr). These results suggested that OnCD3ε was likely to get involved in host immune response against pathogenic challenges.  相似文献   

15.
This study evaluated the effects of the probiotic Lactobacillus plantarum as dietary supplement on growth performance, haemato‐immunological responses, microbiology, histology and transmission electron microscopy of the intestinal epithelium of Nile tilapia challenged with Streptococcus agalactiae. Fish were distributed into two groups: control (unsupplemented) group and the group fed L. plantarum supplemented diet for a period of 58 days. We observed an increase in the concentration of lactic acid bacteria and a reduction in the number of Vibrionaceae in supplemented fish. A significant increase in the final weight, specific growth rate and feed efficiency was also observed in supplemented fish. After challenge, the number of thrombocytes and neutrophils also increased in supplemented animals. Transmission electron microscopy showed damage to the intestinal mucosa and the presence of bacteria similar to S. agalactiae in both infected groups. L. plantarum colonized the intestines of fish, enhanced the growth performance and modulated some haematological parameters.  相似文献   

16.
The intestinal microbiota play an important role in the maintenance of the fish health. In this study, 150 Oreochromis niloticus were divided into five groups (G1–G5) and were subjected to alternate weekly exchange of feeding rate and frequency (3, 3, 1.5, 1.5 and 0%) and (2, 1, 2, 1 and 0 time), respectively, for 8 weeks. Enumeration of total intestinal bacteria revealed that the abundance of Lactobacillus was negatively correlated with those of Aeromonas, Pseudomonas and Edwardsiella. The abundance and proportion of Lactobacillus were affected by the change in feeding frequency. When fish were infected with Aeromonas hydrophila, survival rate significantly decreased in G5 (starved fish) compared with G1 (control group). The pro‐inflammatory cytokines, interleukin (IL)‐1β and tumour necrosis factor‐α, and anti‐inflammatory cytokine IL‐10 as well as serum antibacterial activity and respiratory burst activity were positively correlated with the proportion of Lactobacillus. The alternate weekly exchange of feeding regime did not alter the parametric morphology of the intestine, height and width of intestinal villi, number of goblet cells and width of muscle layer, except in G5. In conclusion, the alternate weekly exchange of feeding regime to starvation (G5), decrease in the feeding frequency to 1 time/day (G3) and decrease in feeding rate to 1.5% (G4) suppressed the immune status of fish, which became vulnerable to bacterial infection. Immune suppression was positively correlated with a decreased proportion of Lactobacillus spp.  相似文献   

17.
Several studies have been demonstrated that phosphotransfer network, through the adenylate kinase (AK) and pyruvate kinase (PK) activities, allows for new perspectives leading to understanding of disease conditions associated with disturbances in energy metabolism, metabolic monitoring and signalling. In this sense, the aim of this study was to evaluate whether experimental infection by Aeromonas caviae alters hepatic AK and PK activities of silver catfish Rhamdia quelen. Hepatic AK and PK activities decreased in infected animals compared to uninfected animals, as well as the hepatic adenosine triphosphate (ATP) levels. Also, a severe hepatic damage was observed in the infected animals due to the presence of dilation and congestion of vessels, degeneration of hepatocytes and loss of liver parenchyma architecture and sinusoidal structure. Therefore, we have demonstrated, for the first time, that experimental infection by A. caviae inhibits key enzymes linked to the communication between sites of ATP generation and ATP utilization. Moreover, the absence of a reciprocal compensatory mechanism between these enzymes contributes directly to hepatic damage and for a severe energetic imbalance, which may contribute to disease pathophysiology.  相似文献   

18.

19.
The intestines of 154 Clarias gariepinus were examined of which 29 were naturally infected with Masenia nkomatiensis, and of these, seven (intensity ranging from 8 to 231) were examined for pathology. Destruction of the epithelium covering the villi, detachment of epithelial cells and parts of villi were observed. Excessive mucus secretion occurred in the vicinity of the worm and catarrh was observed, indicative of an inflammatory response. The number of mucous and mast cells was higher at the attachment site than at an area 5,000 µm away and in uninfected individuals, suggesting that the parasite triggered a localized innate immune response. The number of neutrophils, basophils and lymphocytes in infected tissue was not significantly different from uninfected tissue confirming that no acquired immune response was produced against the maseniid. The caecae in the anterior part of the parasites' intestine consisted of convoluted epithelium forming invaginations or “crypts.” Contraction of the thick layer of circular muscle fibres of the caeca facilitates the movement of digested material. Observation of digested host cells and cell debris within the caecae provides further evidence that M. nkomatiensis is consuming host cells.  相似文献   

20.
The antioxidant and oxidative damage responses and immune parameters in shrimp, Litopenaeus vannamei, reared in clear water (CW) and in a biofloc system (BFT) were evaluated. The animals were given feed supplemented with either nanocapsules containing the antioxidant lipoic acid (NCLA) or empty nanocapsules (NC). Antioxidant and oxidative stress analyses were evaluated by measuring glutathione S‐transferase activity (GST), reduced glutathione (GSH) concentration and lipid peroxidation (TBARS) in the gills, hepatopancreas and muscle. The immune parameters were then determined by the differential hemocyte count in the haemolymph. The final weight of the shrimp reared in both CW and BFT and treated with NCLA increased (p < .05). The shrimps reared in BFT showed increased GST activity in the gills and hepatopancreas after NCLA treatment (p < .05). Higher GSH levels were observed in the hepatopancreas with NCLA supplementation in CW and BFT (p < .05). Decreased levels of TBARS were observed in the gills and muscles of shrimp supplemented with NCLA and maintained in CW (p < .05). A decrease in the percentage of hyaline hemocytes and an increase in granular hemocytes were observed in shrimp treated with NCLA in CW and BFT (p < .05). The antioxidant treatment induced positive responses in terms of the zootechnical, biochemical and immunological parameters.  相似文献   

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