scholarly journals Cyclic Hypoxia Exposure Accelerates the Progression of Amoebic Gill Disease

Pathogens ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 597
Author(s):  
Tina Oldham ◽  
Tim Dempster ◽  
Philip Crosbie ◽  
Mark Adams ◽  
Barbara Nowak
Keyword(s):  
Atlantic Salmon ◽  
Economic Losses ◽  
Post Inoculation ◽  
Diel Pattern ◽  
Marine Aquaculture ◽  
Hypoxia Exposure ◽  
Qpcr Analysis ◽  
Serious Infections ◽  
Gill Disease ◽  
Hypoxic Treatment

Amoebic gill disease (AGD), caused by the amoeba Neoparamoeba perurans, has led to considerable economic losses in every major Atlantic salmon producing country, and is increasing in frequency. The most serious infections occur during summer and autumn, when temperatures are high and poor dissolved oxygen (DO) conditions are most common. Here, we tested if exposure to cyclic hypoxia at DO saturations of 40–60% altered the course of infection with N. perurans compared to normoxic controls maintained at ≥90% DO saturation. Although hypoxia exposure did not increase initial susceptibility to N. perurans, it accelerated progression of the disease. By 7 days post-inoculation, amoeba counts estimated from qPCR analysis were 1.7 times higher in the hypoxic treatment than in normoxic controls, and cumulative mortalities were twice as high (16 ± 4% and 8 ± 2%), respectively. At 10 days post-inoculation, however, there were no differences between amoeba counts in the hypoxic and normoxic treatments, nor in the percentage of filaments with AGD lesions (control = 74 ± 2.8%, hypoxic = 69 ± 3.3%), or number of lamellae per lesion (control = 30 ± 0.9%, hypoxic = 27.9 ± 0.9%) as determined by histological examination. Cumulative mortalities at the termination of the experiment were similarly high in both treatments (hypoxic = 60 ± 2%, normoxic = 53 ± 11%). These results reveal that exposure to cyclic hypoxia in a diel pattern, equivalent to what salmon are exposed to in marine aquaculture cages, accelerated the progression of AGD in post-smolts.

scholarly journals Evaluation of the Infectious Potential of Neoparamoeba perurans Following Freshwater Bathing Treatments

2021 ◽  
Vol 9 (5) ◽  
pp. 967
Author(s):  
Richard S. Taylor ◽  
Joel Slinger ◽  
Chris Stratford ◽  
Megan Rigby ◽  
James W. Wynne
Keyword(s):  
Atlantic Salmon ◽  
Post Treatment ◽  
In Vitro Studies ◽  
Post Inoculation ◽  
Risk Of Infection ◽  
Gill Disease ◽  
Farmed Atlantic Salmon ◽  
Infectious Potential

Freshwater bathing for 2–3 h is the main treatment to control amoebic gill disease of marine-farmed Atlantic salmon. Recent in vitro studies have demonstrated that amoebae (Neoparamoeba perurans) detach when exposed to freshwater and that some eventually reattach to culture plates when returned to seawater. Here, we evaluated the potential for gill-detached N. perurans to survive a commercially relevant treatment and infect AGD-naïve fish and whether holding used bathwater for up to 6 h post treatment would lower infectivity. AGD-affected fish were bathed in freshwater for 2 h. Naïve salmon were exposed to aliquots of the used bathwater after 2, 4, 6 and 8 h. The inoculation was performed at 30 ppt for 2 h, followed by gradual dilution with seawater. Sampling at 20 days post inoculation (dpi) and 40 dpi confirmed rapid AGD development in fish inoculated in 2 h used bathwater, but a slower AGD development following exposure to 4 h bathwater. AGD signs were variable and reduced following longer bathwater holding times. These results suggest that viable amoebae are likely returned to seawater following commercial freshwater treatments, but that the risk of infection can be reduced by retention of bathwater before release.

scholarly journals Investigation of the Initial Host Response of Naïve Atlantic Salmon (Salmo salar) Inoculated with Paramoeba perurans

2021 ◽  
Vol 9 (4) ◽  
pp. 746
Author(s):  
Michelle McCormack ◽  
Eugene Dillon ◽  
Ian O’Connor ◽  
Eugene MacCarthy
Keyword(s):  
Immune Response ◽  
Atlantic Salmon ◽  
Disease Progression ◽  
Salmo Salar ◽  
Host Response ◽  
Post Inoculation ◽  
Serum Samples ◽  
Altered Expression ◽  
Atlantic Salmon Salmo Salar ◽  
Gill Disease

Amoebic Gill Disease (AGD), caused by the ectoparasite Paramoeba perurans is characterised by hyperplasia of the gill epithelium and lamellar fusion. In this study, the initial host response of naïve Atlantic salmon (Salmo salar) inoculated with P. perurans was investigated. Using gel-free proteomic techniques and mass spectrometry gill and serum samples were analysed at 7 timepoints (2, 3, 4, 7, 9, 11 and 14 days) post-inoculation with P. perurans. Differential expression of immune related proteins was assessed by comparison of protein expression from each time point against naïve controls. Few host immune molecules associated with innate immunity showed increased expression in response to gill colonisation by amoebae. Furthermore, many proteins with roles in immune signalling, phagocytosis and T-cell proliferation were found to be inhibited upon disease progression. Initially, various immune factors demonstrated the anticipated increase in expression in response to infection in the serum while some immune inhibition became apparent at the later stages of disease progression. Taken together, the pro-immune trend observed in serum, the lack of a robust early immune response in the gill and the diversity of those proteins in the gill whose altered expression negatively impact the immune response, support the concept of a pathogen-derived suppression of the host response.

scholarly journals Experimental infection of broiler chicks with Salmonella Typhimurium from pigeon (Columba livia)

2016 ◽  
Vol 37 (4) ◽  
pp. 1919
Author(s):  
Átilla Holanda de Albuquerque ◽  
Régis Siqueira de Castro Teixeira ◽  
Débora Nishi Machado ◽  
Elisângela De Souza Lopes ◽  
Ruben Horn Vasconcelos ◽  
...  
Keyword(s):  
Salmonella Typhimurium ◽  
Clinical Signs ◽  
Columba Livia ◽  
Poultry Feed ◽  
Economic Losses ◽  
Control Group ◽  
Broiler Chicks ◽  
Post Inoculation ◽  
Microbiological Analysis ◽  
Fecal Samples

Several cases of animal and human salmonellosis caused by the Salmonella serotype Typhimurium have been reported. In animals, subclinical infection favors pathogen dissemination through feces. In this context, the domestic pigeon (Columba livia) with an asymptomatic condition may play an important role in the transmission of salmonellosis, through the elimination of contaminated feces in commercial aviaries or in poultry feed facilities, causing economic losses to the poultry industry and presenting a risk to public health. This study aimed to evaluate the mortality, clinical signs and the presence of Salmonella Typhimurium in the feces and organs of chicks previously inoculated with bacteria isolated from a pigeon. One-day-old chicks were distributed in two experimental groups (G1 and G2) of 32 birds each, and a control group of six birds. Two inocula of 0.4 and 0.7 mL with 105 and 106 colony forming units were used in G1 and G2 birds, respectively. At 1, 4, 7 and 14 days post-inoculation (dpi) fecal samples were pooled from each cage and individual cloacal swabs were collected. At 14 dpi, all chicks were euthanized and samples were collected from the liver, spleen, lung, cecum and intestine for microbiological analysis. Mortality was only observed among G2 birds (6.25%). Most birds presented clinical signs of diarrhea at 4 dpi and no symptom as observed at 14 dpi. The results from cloacal swabs demonstrated bacterial elimination in 68.8% and 53.1% of G2 and G1 birds, respectively at 1 dpi. Additionally, fecal samples had elevated bacterial shedding in all four periods of observation , with a higher excretion at 4 dpi (62.5%) for both groups. Among G2 birds, 74.2% were positive for the pathogen in the intestine; G1 birds presented the lowest rate of lung infection (29%), and both groups had more than 50% positivity for liver and caeca. The results revealed that infected chicks with a Salmonella Typhimurium strains isolated from pigeons may host the pathogen in several organs, and simultaneously present diarrheic disorders with significant levels of bacterial excretion in feces.

Transcriptome profiling the gills of amoebic gill disease (AGD)-affected Atlantic salmon (Salmo salarL.): a role for tumor suppressor p53 in AGD pathogenesis?

2006 ◽  
Vol 26 (1) ◽  
pp. 15-34 ◽  
Author(s):  
Richard N. Morrison ◽  
Glenn A. Cooper ◽  
Ben F. Koop ◽  
Matthew L. Rise ◽  
Andrew R. Bridle ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Atlantic Salmon ◽  
Gill Tissue ◽  
Transcriptome Profiling ◽  
Global Gene Expression ◽  
Nuclear Antigen ◽  
Independent Experiment ◽  
Gill Disease ◽  
P53 Tumor Suppressor Protein ◽  
Microarray Analyses

Neoparamoeba spp. are amphizoic amoebae with the capacity to colonize the gills of some marine fish, causing AGD. Here, the gill tissue transcriptome response of Atlantic salmon ( Salmo salar L.) to AGD is described. Tanks housing Atlantic salmon were inoculated with Neoparamoeba spp. and fish sampled at time points up to 8 days postinoculation (pi.). Gill tissues were taken from AGD-affected fish, and a DNA microarray was used to compare global gene expression against tissues from AGD-unaffected fish. A total of 206 genes, representing 190 unique transcripts, were reproducibly identified as up- or downregulated in response to Neoparamoeba spp. infection. Informative transcripts having GO biological process identifiers were grouped according to function. Although a number of genes were placed into each category, no distinct patterns were observed. One Atlantic salmon cDNA that was upregulated in infected gill relative to noninfected gill at 114 and 189 h pi. showed significant identity with the Xenopus, mouse, and human anterior gradient-2 (AG-2) homologs. Two Atlantic salmon AG-2 mRNA transcripts, designated asAG-2/1 and asAG-2/2, were cloned, sequenced, and shown to be predominantly expressed in the gill, intestine, and brain of a healthy fish. In AGD-affected fish, differential asAG-2 expression was confirmed in samples used for microarray analyses as well as in AGD-affected gill tissue taken from fish in an independent experiment. The asAG-2 upregulation was restricted to AGD lesions relative to unaffected tissue from the same gill arch, while p53 tumor suppressor protein mRNA was concurrently downregulated in AGD lesions. Differential expression of p53-regulated transcripts, proliferating cell nuclear antigen and growth arrest and DNA damage-inducible gene-45β (GADD45β) in AGD lesions, suggests a role for p53 in AGD pathogenesis. Thus AGD may represent a novel model for comparative analysis of p53 and p53-regulated pathways.

scholarly journals Matrine exhibits antiviral activity in a PRRSV/PCV2 co-infected mouse model

2020 ◽  
Author(s):  
Na Sun ◽  
Hua Zhang ◽  
Panpan Sun ◽  
Ajab Khan ◽  
Jianhua Guo ◽  
...  
Keyword(s):  
Mouse Model ◽  
Interstitial Pneumonia ◽  
Normal Control ◽  
Virus Replication ◽  
Pcv2 Infection ◽  
Economic Losses ◽  
Treatment Groups ◽  
Qpcr Analysis ◽  
Antiviral Activities ◽  
Pcv2 Replication

Abstract BackgroundPRRSV and PCV2 co-infection is very common in swine industry which results in huge economic losses worldwide. Although vaccination is used to prevent viral diseases, immunosuppression induced by PRRSV and PCV2 leads to vaccine failure. Our previous results have demonstrated that Matrine possessed antiviral activities against PRRSV/PCV2 co-infection in vitro. To establish a PRRSV/PCV2 co-infected KM mouse model and evaluate the antiviral activities of Matrine against PRRSV/PCV2 co-infection. A total of 144 KM mice were randomly divided into six groups with 24 mice in each group, named as: normal control, PRRSV/PCV2 co-infected group (PRRSV/PCV2 group), Ribavirin treatment positive control (Ribavirin control) and Matrine treatment groups (Matrine 40 mg/kg, Matrine 20 mg/kg and Matrine 10 mg/kg). Except normal control group, all mice in other five groups were inoculated with PRRSV, followed by PCV2 at 2 h later. At 7 days post-infection (dpi), mice in the treatment groups were intraperitoneally administered with various doses of Matrine and Ribavirin, twice a day for 5 consecutive days. ResultsPRRSV N and PCV2 CAP genes were detected by PCR in multiple tissues including heart, liver, spleen, lungs, kidneys, thymus and inguinal lymph nodes. The viral load of PCV2 was the highest in liver followed by thymus and spleen. Although PRRSV were detected in most of the tissues, but the replication of PRRSV was not significantly increased, as shown by qPCR analysis. Comparing with PCV2 infection alone, PRRSV infection significantly elevated PCV2 replication and also exacerbated PCV2 induced interstitial pneumonia. qPCR analysis demonstrated that 40 mg/ml Matrine significantly attenuated PCV2 replication in liver and alleviated virus induced interstitial pneumonia, suggesting that Matrine could directly inhibit virus replication. In addition, Matrine treatment enhanced peritoneal macrophages phagocytosis at 13 and 16 dpi, and 40 mg/kg of Matrine increased the proliferation activity of lymphocytes. Body weight gain was continuously promoted by administrating Matrine at 10 mg/kg.ConclusionMatrine possessed antiviral activities via inhibiting virus replication and regulating immune functions in mice co-infected by PRRSV/PCV2. These data provide new insight into controlling PRRSV and PCV2 infection and support further the research for developing Matrine as a new possible veterinary medicine.

scholarly journals Expression analysis of defense-related genes in cucumber (Cucumis sativus L.) against Phytophthora melonis

2020 ◽  
Author(s):  
Lida Hashemi ◽  
Ahmad Reza Golparvar ◽  
Mehdi Nasr Esfahani ◽  
Maryam Golabadi
Keyword(s):  
Gene Expression ◽  
Expression Analysis ◽  
Gene Expression Analysis ◽  
Molecular Mechanisms ◽  
Crown Rot ◽  
Economic Losses ◽  
Post Inoculation ◽  
Expression Ratio ◽  
Phytophthora Melonis ◽  
Maximum Expression

AbstractPhytophthora melonis is the causal agent of damping-off or crown rot, one of the most destructive cucumber diseases that causes severe economic losses in Iran and some other parts of the world. Despite intense research efforts made in the past years, no permanent cure currently exists for this disease. With the aim to understand the molecular mechanisms of defense against P. melonis, root collars and leaves of four cucumber genotypes consisting of resistant Ramezz; moderately resistant Baby and very susceptible Mini 6-23 and Extrem, were monitored for quantitative gene expression analysis of five antifungal and/or anti-oomycete genes (CsWRKY20, CsLecRK6.1, PR3, PR1-1a and LOX1) at three points after inoculation with P. melonis. The gene expression analysis indicated that P. melonis strongly enhanced the expression of these genes after inoculation in both leaves and root collars. Further, not only the transcript levels of these genes were significantly higher in the resistant and moderately resistance genotypes, but also the time point of the highest relative expression ratio for the five genes was different in the four cucumber genotypes. CsWRKY20 and PR3 showed the maximum expression in Ramezz at 48 hours post inoculation (hpi) while CsLecRK6.1, and LOX1 showed the highest expression at 72 hpi. In addition, PR1-1a showed the maximum expression in the Baby at 72 hpi. Root collars responded faster than leaves and some responses were more strongly up-regulated in root collars than in leaves. The genes found to be involved in disease resistance in two different organs of cucumber after pathogen infection. The results suggest that increased expression of these genes led to activation of defense pathways and could be responsible for a reduced P. melonis colonization capacity in Ramezz and Baby. Overall, this work represents a valuable resource for future functional genomics studies to unravel the molecular mechanisms of C. sativus- P. melonis interaction.

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