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Zhang D, Zhou G, Thongda W, Li C, Ye Z, Zhao H, Beck BH, Mohammed H, Peatman E. Early divergent responses to virulent and attenuated vaccine isolates of Flavobacterium covae sp. nov. In channel catfish, Ictalurus punctatus. FISH & SHELLFISH IMMUNOLOGY 2024; 144:109248. [PMID: 38030028 DOI: 10.1016/j.fsi.2023.109248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 11/14/2023] [Accepted: 11/23/2023] [Indexed: 12/01/2023]
Abstract
Columnaris disease continues to inflict substantial losses among freshwater cultured species since its first description one hundred years ago. The experimental and anecdotal evidence suggests an expanded range and rising virulence of columnaris worldwide due to the warming global climate. The channel catfish (Ictalurus punctatus) are particularly vulnerable to columnaris. A recently developed live attenuated vaccine (17-23) for Flavobacterium columnare (now Flavobacterium covae sp. nov.) demonstrated superior protection for vaccinated catfish against genetically diverse columnaris isolates. In this study, we aimed to elucidate the molecular mechanisms and patterns of immune evasion and host manipulation linked to virulence by comparing gene expression changes in the host after the challenge with a virulent (BGSF-27) or live attenuated F. covae sp. nov. vaccine (17-23). Thirty-day-old fry were accordingly challenged with either virulent or vaccine isolates. Gill tissues were collected at 0 h (control), 1 h, and 2 h post-infection, which are two critical time points in early host-pathogen interactions. Transcriptome profiling of the gill tissues revealed a larger number (518) of differentially expressed genes (DEGs) in vaccine-exposed fish than those exposed to the virulent pathogen (321). Pathway analyses suggested potent suppression of early host immune responses by the virulent isolate through a higher expression of nuclear receptor corepressors (NCoR) responsible for antagonizing macrophage and T-cell signaling. Conversely, in vaccinated fry, we observed induction of Ca2+/calmodulin-dependent protein kinase II (CAMKII), responsible for clearing NCoR, and commensurate up-regulation of transcription factor AP-1 subunits, c-Fos, and c-Jun. As in mammalian systems, AP-1 expression was connected with a broad immune activation in vaccinated fry, including induction of CC chemokines, proteinases, iNOS, and IL-12b. Relatedly, divergent expression patterns of Src tyrosine kinase Lck, CD44, and CD28 indicated a delay or suppression of T-cell adhesion and activation in fry exposed to the virulent isolate. Broader implications of these findings will be discussed. The transcriptomic differences between virulent and attenuated bacteria may offer insights into how the host responds to the vaccination or infection and provide valuable knowledge to understand the early immune mechanisms of columnaris disease in aquaculture.
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Affiliation(s)
- Dongdong Zhang
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, School of Marine Bilology and Fisheries, Hainan University, Haikou, 570228, PR China; School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA; College of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya, PR China
| | - Gengfu Zhou
- Hainan Provincial Key Laboratory for Tropical Hydrobiology and Biotechnology, School of Marine Bilology and Fisheries, Hainan University, Haikou, 570228, PR China
| | - Wilawan Thongda
- Center of Excellence for Shrimp Molecular Biology and Biotechnology (CENTEX Shrimp), Faculty of Science, Mahidol University, Bangkok, 10400, Thailand; National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, 12120, Thailand
| | - Chao Li
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Zhi Ye
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Honggang Zhao
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Benjamin H Beck
- United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, Auburn, AL, 36832, USA
| | - Haitham Mohammed
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Eric Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA.
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Levipan HA, Avendaño-Herrera R. Assessing the impacts of skin mucus from Salmo salar and Oncorhynchus mykiss on the growth and in vitro infectivity of the fish pathogen Piscirickettsia salmonis. JOURNAL OF FISH DISEASES 2021; 44:181-190. [PMID: 33006764 DOI: 10.1111/jfd.13275] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/03/2020] [Accepted: 09/04/2020] [Indexed: 06/11/2023]
Abstract
Piscirickettsiosis is a fish disease caused by the facultative intracellular bacterium, Piscirickettsia salmonis. Even though entry routes of P. salmonis in fish are not fully clear yet, the skin seems to be the main portal in some salmonid species. Despite the importance of fish mucous skin barrier in fighting waterborne pathogens, the interaction between salmonid skin mucus and the bacterium is unknown. This study seeks to determine the in vitro changes in the growth of two Chilean P. salmonis strains (LF-89-like and EM-90-like genotypes) and the type strain LF-89T under exposures to skin mucus from Salmo salar and Oncorhynchus mykiss, as well as changes in the cytotoxic effect of P. salmonis on the SHK-1 cells following exposures. The results suggest that the growth of three P. salmonis strains was not significantly negatively affected under exposures to skin mucus (adjusted at 100 μg total protein ml-1 ) of O. mykiss (69 ± 18 U lysozyme ml-1 ) and S. salar (48 ± 33 U lysozyme ml-1 ) over time. However, the cytotoxic effect of P. salmonis, pre-exposed to salmonid skin mucus, on the SHK-1 cell line was reliably identified only towards the end of the incubation period, suggesting that the mucus had a delaying effect on the cytotoxic response of the cell line to the bacterium. These results represent a baseline knowledge to open new avenues of research intended to understand how P. salmonis faces the fish mucous skin barrier.
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Affiliation(s)
- Héctor A Levipan
- Departamento de Biología, Facultad de Ciencias Naturales y Exactas, Universidad de Playa Ancha, Valparaíso, Chile
| | - Ruben Avendaño-Herrera
- Laboratorio de Patología de Organismos Acuáticos y Biotecnología Acuícola, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andrés Bello, Viña del Mar, Chile
- Interdisciplinary Center for Aquaculture Research, Universidad Andrés Bello, Viña del Mar, Chile
- Centro de Investigación Marina Quintay (CIMARQ), Universidad Andrés Bello, Quintay, Chile
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Kumru S, Tekedar HC, Blom J, Lawrence ML, Karsi A. Genomic diversity in flavobacterial pathogens of aquatic origin. Microb Pathog 2020; 142:104053. [PMID: 32058022 DOI: 10.1016/j.micpath.2020.104053] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 02/07/2020] [Accepted: 02/07/2020] [Indexed: 12/15/2022]
Abstract
Flavobacterium species are considered important fish pathogens in wild and cultured fish throughout the world. They can cause acute, subacute, and chronic infections, which are mainly characterized by gill damage, skin lesions, and deep necrotic ulcerations. Primarily, three Flavobacterium species, F. branchiophilum, F. columnare, and F. psychrophilum, have been reported to cause substantial losses to freshwater fish. In this study, we evaluated genomes of 86 Flavobacterium species isolated from aquatic hosts (mainly fish) to identify their unique and shared genome features. Our results showed that F. columnare genomes cluster into four different genetic groups. In silico secretion system analysis identified that all genomes carry type I (T1SS) and type IX (T9SS) secretion systems, but the number of type I secretion system genes shows diversity between species. F. branchiophilum, F. araucananum, F. chilense, F. spartansii, and F. tructae genomes have full type VI secretion system (T6SS). F. columnare, F. hydatis, and F. plurextorum carry partial T6SS with some of the T6SS genes missing. F. columnare, F. araucananum, F. chilense, F. spartansii, F. araucananum, F. tructae, Flavobacterium sp., F. crassostreae, F. succinicans, F. hydatis, and F. plurextorum carry most of the type IV secretion system genes (T4SS). F. columnare genetic groups 1 and 2, Flavobacterium sp., and F. crassostreae encode the least number of antibiotic resistance elements. F. hydatis, F. chilense, and F. plurextorum encode the greatest number of antibiotic resistance genes. Additionally, F. spartansii, F. araucananum, and chilense encode the greatest number of virulence genes while Flavobacterium sp. and F. crassostreae encode the least number of virulence genes. In conclusion, comparative genomics of Flavobacterium species of aquatic origin will help our understanding of Flavobacterium pathogenesis.
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Affiliation(s)
- Salih Kumru
- Faculty of Fisheries, Recep Tayyip Erdogan University, Rize, Turkey
| | - Hasan C Tekedar
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Jochen Blom
- Bioinformatics and Systems Biology, Justus-Liebig-University Giessen, Giessen, Hesse, Germany
| | - Mark L Lawrence
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Attila Karsi
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States.
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4
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Lange MD, Farmer BD, Abernathy J. Vertebrate mucus stimulates biofilm development and upregulates iron acquisition genes in Flavobacterium columnare. JOURNAL OF FISH DISEASES 2020; 43:101-110. [PMID: 31709555 DOI: 10.1111/jfd.13103] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Revised: 10/01/2019] [Accepted: 10/03/2019] [Indexed: 06/10/2023]
Abstract
Columnaris disease is responsible for substantial losses throughout the production of many freshwater fish species. One of the ways in which the bacterium Flavobacterium columnare is so effective in initiating disease is through the formation of biofilms on fish skin and gills. To further explore the interaction between host factors and bacterial cells, we assayed the ability of vertebrate mucus to enhance F. columnare biofilm development. Different concentrations of catfish, tilapia and pig mucus (5-60 µg/ml) increased biofilm growth at varying degrees among F. columnare isolates. Our data suggest that vertebrate mucus acts as a signalling molecule for the development of F. columnare biofilms; however, there are clear disparities in how individual isolates respond to different mucus fractions to stimulate biofilms. The expression of iron acquisition genes among two genomovar II isolates showed that ferroxidase, TonB receptor and the siderophore synthetase gene were all significantly upregulated among F. columnare biofilms. Interestingly, the siderophore acetyltransferase gene was only shown to be significantly upregulated in one of the genomovar II isolates. This work provides insight into our understanding of the interaction between F. columnare and vertebrate mucus, which likely contributes to the growth of planktonic cells and the transition into biofilms.
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Affiliation(s)
- Miles D Lange
- United States Department of Agriculture, Agricultural Research Service, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
| | - Bradley D Farmer
- United States Department of Agriculture, Agricultural Research Service, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
| | - Jason Abernathy
- United States Department of Agriculture, Agricultural Research Service, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
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5
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Almeida GMF, Laanto E, Ashrafi R, Sundberg LR. Bacteriophage Adherence to Mucus Mediates Preventive Protection against Pathogenic Bacteria. mBio 2019; 10:e01984-19. [PMID: 31744913 PMCID: PMC6867891 DOI: 10.1128/mbio.01984-19] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 10/17/2019] [Indexed: 11/20/2022] Open
Abstract
Metazoans were proposed to host bacteriophages on their mucosal surfaces in a symbiotic relationship, where phages provide an external immunity against bacterial infections and the metazoans provide phages a medium for interacting with bacteria. However, scarce empirical evidence and model systems have left the phage-mucus interaction poorly understood. Here, we show that phages bind both to porcine mucus and to rainbow trout (Oncorhynchus mykiss) primary mucus, persist up to 7 days in the mucosa, and provide protection against Flavobacterium columnare Also, exposure to mucus changes the bacterial phenotype by increasing bacterial virulence and susceptibility to phage infections. This trade-off in bacterial virulence reveals ecological benefit of maintaining phages in the metazoan mucosal surfaces. Tests using other phage-bacterium pairs suggest that phage binding to mucus may be widespread in the biosphere, indicating its importance for disease, ecology, and evolution. This phenomenon may have significant potential to be exploited in preventive phage therapy.IMPORTANCE The mucosal surfaces of animals are habitat for microbes, including viruses. Bacteriophages-viruses that infect bacteria-were shown to be able to bind to mucus. This may result in a symbiotic relationship in which phages find bacterial hosts to infect, protecting the mucus-producing animal from bacterial infections in the process. Here, we studied phage binding on mucus and the effect of mucin on phage-bacterium interactions. The significance of our research is in showing that phage adhesion to mucus results in preventive protection against bacterial infections, which will serve as basis for the development of prophylactic phage therapy approaches. Besides, we also reveal that exposure to mucus upregulates bacterial virulence and that this is exploited by phages for infection, adding one additional layer to the metazoan-bacterium-phage biological interactions and ecology. This phenomenon might be widespread in the biosphere and thus crucial for understanding mucosal diseases, their outcome and treatment.
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Affiliation(s)
- Gabriel M F Almeida
- Department of Biological and Environmental Science, University of Jyvaskyla, Jyvaskyla, Finland
- Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
| | - Elina Laanto
- Department of Biological and Environmental Science, University of Jyvaskyla, Jyvaskyla, Finland
- Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
| | - Roghaieh Ashrafi
- Department of Biological and Environmental Science, University of Jyvaskyla, Jyvaskyla, Finland
- Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
| | - Lotta-Riina Sundberg
- Department of Biological and Environmental Science, University of Jyvaskyla, Jyvaskyla, Finland
- Nanoscience Center, University of Jyvaskyla, Jyvaskyla, Finland
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6
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Functional Aspects of Fish Mucosal Lectins-Interaction with Non-Self. Molecules 2018; 23:molecules23051119. [PMID: 29747390 PMCID: PMC6100423 DOI: 10.3390/molecules23051119] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 05/05/2018] [Accepted: 05/07/2018] [Indexed: 01/09/2023] Open
Abstract
Mucosal surfaces are of key importance in protecting animals against external threats including pathogens. In the mucosal surfaces, host molecules interact with non-self to prevent infection and disease. Interestingly, both inhibition and stimulation of uptake hinder infection. In this review, the current knowledgebase on teleost mucosal lectins’ ability to interact with non-self is summarised with a focus on agglutination, growth inhibition, opsonisation, cell adhesion, and direct killing activities. Further research on lectins is essential, both to understand the immune system of fishes, since they rely more on the innate immune system than mammals, and also to explore these molecules’ antibiotic and antiparasitic activities against veterinary and human pathogens.
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7
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Penttinen R, Hoikkala V, Sundberg LR. Gliding Motility and Expression of Motility-Related Genes in Spreading and Non-spreading Colonies of Flavobacterium columnare. Front Microbiol 2018; 9:525. [PMID: 29632520 PMCID: PMC5879114 DOI: 10.3389/fmicb.2018.00525] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 03/08/2018] [Indexed: 11/13/2022] Open
Abstract
Gliding motility facilitates the movement of bacteria along surfaces in many Bacteroidetes species and results in spreading colonies. The adhesins required for the gliding are secreted through a gliding motility-associated protein secretion system, known as the type IX secretion system (T9SS). The fish pathogen Flavobacterium columnare produces spreading (rhizoid [Rz], soft [S]) and non-spreading (rough [R]) colony types, of which only the spreading Rz type is virulent. In this study, we explored the spreading behavior of these colony types by microscopic imaging and measured the expression of genes associated with gliding motility and T9SS (gldG, gldH, gldL, sprA, sprB, sprE, sprF, sprT, and porV) under high and low resource levels by using RT-qPCR (reverse transcription quantitative PCR). The spreading colony types responded to the low resource level with increased colony size. The non-spreading colony type, as well as the cells growing under high nutrient level expressed only moderate cell movements. Yet, a low nutrient level provoked more active gliding motility in individual cells and increased spreading by cooperative gliding. The gene expression survey demonstrated an increased expression level of sprA (a core component of T9SS) and sprF (needed for adhesin secretion) under low nutrient conditions. Surprisingly, the expression of gliding motility genes was not consistently associated with more active spreading behavior. Furthermore, no genetic differences were found between spreading and non-spreading colony types in the studied genes associated with gliding motility. Our study demonstrates that environmental nutrient level is an important regulator of both gliding motility and the expression of some of the associated genes. These results may help to understand the connections between nutrient concentration, gliding motility, and virulence of F. columnare.
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Affiliation(s)
- Reetta Penttinen
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Ville Hoikkala
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
| | - Lotta-Riina Sundberg
- Centre of Excellence in Biological Interactions, Department of Biological and Environmental Science and Nanoscience Center, University of Jyväskylä, Jyväskylä, Finland
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Zhou Y, Liu LY, He TT, Laghari ZA, Nie P, Gao Q, Xie HX. Edwardsiella tarda EsaE (Orf19 protein) is required for the secretion of type III substrates, and pathogenesis in fish. Vet Microbiol 2016; 190:12-18. [DOI: 10.1016/j.vetmic.2016.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Revised: 04/14/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
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9
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Papadopoulou A, Howell A, Wiklund T. Inhibition ofFlavobacterium psychrophilumadhesionin vitro. FEMS Microbiol Lett 2015; 362:fnv203. [DOI: 10.1093/femsle/fnv203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/19/2015] [Indexed: 11/12/2022] Open
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10
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Peatman E, Lange M, Zhao H, Beck BH. Physiology and immunology of mucosal barriers in catfish (Ictalurus spp.). Tissue Barriers 2015; 3:e1068907. [PMID: 26716071 DOI: 10.1080/21688370.2015.1068907] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/23/2015] [Accepted: 06/27/2015] [Indexed: 10/23/2022] Open
Abstract
The mucosal barriers of catfish (Ictalurus spp) constitute the first line of defense against pathogen invasion while simultaneously carrying out a diverse array of other critical physiological processes, including nutrient adsorption, osmoregulation, waste excretion, and environmental sensing. Catfish depend more heavily on mucosal barriers than their terrestrial counterparts as they are continuously interacting with the aquatic microbiota. Our understanding of these barriers, while growing, is still limited relative to that of mammalian model systems. Nevertheless, a combination of molecular and cellular studies in catfish over the last few decades, and particularly within the last few years, has helped to elucidate many of the primary actors and pathways critical to their mucosal health. Here we describe aspects of innate and adaptive immune responses in the primary mucosal tissues (skin, gill, and intestine) of catfish, focusing on mucus-driven responses, pathogen recognition, soluble mediators, and immunoglobulin and T-cell derived immunity. Modulation of mucosal barriers will be critical moving forward for crafting better diets, improving vaccine delivery, enhancing water quality, and ensuring sustainable production practices in catfish.
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Affiliation(s)
- Eric Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences; Auburn University ; Auburn, AL USA
| | - Miles Lange
- United States Department of Agriculture; Agricultural Research Service; Stuttgart National Aquaculture Research Center ; Stuttgart, AR USA
| | - Honggang Zhao
- School of Fisheries, Aquaculture, and Aquatic Sciences; Auburn University ; Auburn, AL USA
| | - Benjamin H Beck
- United States Department of Agriculture; Agricultural Research Service; Stuttgart National Aquaculture Research Center ; Stuttgart, AR USA
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11
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Kolton M, Frenkel O, Elad Y, Cytryn E. Potential role of Flavobacterial gliding-motility and type IX secretion system complex in root colonization and plant defense. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2014; 27:1005-1013. [PMID: 24921925 DOI: 10.1094/mpmi-03-14-0067-r] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Members of the Flavobacterium genus are often highly abundant in the rhizosphere. Nevertheless, the physiological characteristics associated with their enhanced rhizosphere competence are currently an enigma. Flavobacteria possess a unique gliding-motility complex that is tightly associated with a recently characterized Bacteroidetes-specific type IX protein secretion system, which distinguishes them from the rest of the rhizosphere microbiome. We hypothesize that proper functionality of this complex may confer a competitive advantage in the rhizosphere. To test this hypothesis, we constructed mutant and complement root-associated flavobacterial variants with dysfunctional secretion and gliding motility, and tested them in a series of in planta experiments. These mutants demonstrated significantly lower rhizosphere persistence (approximately 10-fold), plant root colonization (approximately fivefold), and seed adhesion capacity (approximately sevenfold) than the wild-type strains. Furthermore, the biocontrol capacity of the mutant strain toward foliar-applied Clavibacter michiganensis was significantly impaired relative to the wild-type strain, suggesting a role of the gliding and secretion complex in plant protection. Collectively, these results provide an initial link between the high abundance of flavobacteria in the rhizosphere and their unique physiology, indicating that the flavobacterial gliding-motility and secretion complex may play a central role in root colonization and plant defense.
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12
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Wang X, Li C, Thongda W, Luo Y, Beck B, Peatman E. Characterization and mucosal responses of interleukin 17 family ligand and receptor genes in channel catfish Ictalurus punctatus. FISH & SHELLFISH IMMUNOLOGY 2014; 38:47-55. [PMID: 24602926 DOI: 10.1016/j.fsi.2014.02.020] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/17/2014] [Accepted: 02/23/2014] [Indexed: 06/03/2023]
Abstract
Interleukin (IL) 17 family cytokines are important mediators of mucosal immune responses, tightly regulated by signals from the complex milieu of pathogenic and commensal microbes, epithelial cells and innate and adaptive leukocytes found at tissue barriers. In mammals, IL17 ligand expression has been linked not only to protective immunity but also excessive tissue inflammation and damage in the gut and lungs. To better understand the scope and action of the IL17 family in channel catfish Ictalurus punctatus, we identified and characterized seven IL17 ligands and four IL17 receptor (IL17R) homologues from transcriptomic and genomic databases. To gain insight into the mucosal actions of the IL17A/Fs-associated pathway in inflammatory processes, the expression profiles of three IL17A/Fs and their putative receptors IL17RA and IL17RC in mucosal tissues of catfish following experimental challenge with Edwardsiella ictaluri and Flavobacterium columnare were investigated. Bacterial challenge induced higher expression of the catfish IL17A/Fs as early at 4 h post-infection, particularly in gill tissue. In contrast, in the catfish intestine, where IL17 function is best understood in mouse models, IL17A/F expression showed minimal early responses to E. ictaluri infection. Instead, a significant up-regulation of IL17 ligands and receptors was observed in the intestine at 7 d, highlighting species and tissue-specific regulation of the IL17 family.
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Affiliation(s)
- Xingqiang Wang
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, AL 36849, USA; Jiangsu Key Laboratory of Marine Biotechnology, Huaihai Institute of Technology, Lianyungang 222005, China
| | - Chao Li
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, AL 36849, USA
| | - Wilawan Thongda
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, AL 36849, USA
| | - Yupeng Luo
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, AL 36849, USA
| | - Benjamin Beck
- United States Department of Agriculture, Stuttgart National Aquaculture Research Center, Stuttgart, AR 72160, USA
| | - Eric Peatman
- School of Fisheries, Aquaculture and Aquatic Sciences, Auburn University, AL 36849, USA.
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13
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Peatman E, Li C, Peterson BC, Straus DL, Farmer BD, Beck BH. Basal polarization of the mucosal compartment in Flavobacterium columnare susceptible and resistant channel catfish (Ictalurus punctatus). Mol Immunol 2013; 56:317-27. [PMID: 23895942 DOI: 10.1016/j.molimm.2013.04.014] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/18/2013] [Accepted: 04/29/2013] [Indexed: 01/30/2023]
Abstract
The freshwater bacterial pathogen, Flavobacterium columnare, infects a variety of ornamental and farmed fish species worldwide through mucosal attachment points on the gill and skin. While previous studies have demonstrated a chemotactic response of F. columnare to fish mucus, little is known about how host gill mucosal molecular and cellular constituents may impact rates of adhesion, tissue invasion, and ultimately, mortality. Here, we describe the use of RNA-seq to profile gill expression differences between channel catfish (Ictalurus punctatus) differing in their susceptibility to F. columnare both basally (before infection) and at three early timepoints post-infection (1 h, 2 h, and 8 h). After sequencing and de novo assembly of over 350 million 100 base-pair transcript reads, between group comparisons revealed 1714 unique genes differentially expressed greater than 1.5-fold at one or more timepoints. In the large dataset, we focused our analysis on basal differential expression between resistant and susceptible catfish as these genes could potentially reveal genetic and/or environmental factors linked with differential rates of infection. A number of critical innate immune components including iNOS2b, lysozyme C, IL-8, and TNF-alpha were constitutively higher in resistant catfish gill, while susceptible fish showed high expression levels of secreted mucin forms, a rhamnose-binding lectin previously linked to susceptibility, and mucosal immune factors such as CD103 and IL-17. Taken together, the immune and mucin profiles obtained by RNA-seq suggest a basal polarization in the gill mucosa, with susceptible fish possessing a putative mucosecretory, toleragenic phenotype which may predispose them to F. columnare infection.
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Affiliation(s)
- Eric Peatman
- Department of Fisheries and Allied Aquacultures, Auburn University, Auburn, AL 36849, USA.
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14
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Biofilm formation by the fish pathogen Flavobacterium columnare: development and parameters affecting surface attachment. Appl Environ Microbiol 2013; 79:5633-42. [PMID: 23851087 DOI: 10.1128/aem.01192-13] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flavobacterium columnare is a bacterial fish pathogen that affects many freshwater species worldwide. The natural reservoir of this pathogen is unknown, but its resilience in closed aquaculture systems posits biofilm as the source of contagion for farmed fish. The objectives of this study were (i) to characterize the dynamics of biofilm formation and morphology under static and flow conditions and (ii) to evaluate the effects of temperature, pH, salinity, hardness, and carbohydrates on biofilm formation. Nineteen F. columnare strains, including representatives of all of the defined genetic groups (genomovars), were compared in this study. The structure of biofilm was characterized by light microscopy, confocal laser scanning microscopy, and scanning electron microscopy. F. columnare was able to attach to and colonize inert surfaces by producing biofilm. Surface colonization started within 6 h postinoculation, and microcolonies were observed within 24 h. Extracellular polysaccharide substances and water channels were observed in mature biofilms (24 to 48 h). A similar time course was observed when F. columnare formed biofilm in microfluidic chambers under flow conditions. The virulence potential of biofilm was confirmed by cutaneous inoculation of channel catfish fingerlings with mature biofilm. Several physicochemical parameters modulate attachment to surfaces, with the largest influence being exerted by hardness, salinity, and the presence of mannose. Maintenance of hardness and salinity values within certain ranges could prevent biofilm formation by F. columnare in aquaculture systems.
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Declercq AM, Haesebrouck F, Van den Broeck W, Bossier P, Decostere A. Columnaris disease in fish: a review with emphasis on bacterium-host interactions. Vet Res 2013; 44:27. [PMID: 23617544 PMCID: PMC3648355 DOI: 10.1186/1297-9716-44-27] [Citation(s) in RCA: 196] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 04/10/2013] [Indexed: 11/10/2022] Open
Abstract
Flavobacterium columnare (F. columnare) is the causative agent of columnaris disease. This bacterium affects both cultured and wild freshwater fish including many susceptible commercially important fish species. F. columnare infections may result in skin lesions, fin erosion and gill necrosis, with a high degree of mortality, leading to severe economic losses. Especially in the last decade, various research groups have performed studies aimed at elucidating the pathogenesis of columnaris disease, leading to significant progress in defining the complex interactions between the organism and its host. Despite these efforts, the pathogenesis of columnaris disease hitherto largely remains unclear, compromising the further development of efficient curative and preventive measures to combat this disease. Besides elaborating on the agent and the disease it causes, this review aims to summarize these pathogenesis data emphasizing the areas meriting further investigation.
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Affiliation(s)
- Annelies Maria Declercq
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Wim Van den Broeck
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Peter Bossier
- Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Ghent, Belgium
| | - Annemie Decostere
- Department of Morphology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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Pridgeon JW, Mu X, Klesius PH. Biochemical and molecular characterization of the novobiocin and rifampicin resistant Aeromonas hydrophila vaccine strain AL09-71N+R compared to its virulent parent strain AL09-71. Vet Microbiol 2013; 165:349-57. [PMID: 23608477 DOI: 10.1016/j.vetmic.2013.03.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 03/04/2013] [Accepted: 03/18/2013] [Indexed: 01/07/2023]
Abstract
To understand the fitness cost of novobiocin- and rifampicin-resistance in an attenuated Aeromonas hydrophiila vaccine strain AL09-71 N+R compared to its virulent parent strain AL09-71, colony size, cell size, cell proliferation rate, chemotactic response, and the ability to invade catfish gill cells of the two strains were compared. Our results revealed that: (1) the cell size and the colony size of AL09-71 N+R was significantly (P<0.05) smaller than that of AL09-71; (2) the proliferation rate of AL09-71 N+R was significantly (P<0.05) slower than that of AL09-71; (3) AL09-71 N+R had a significantly (P<0.05) lower chemotactic response to catfish mucus than that of AL09-71; 4) the ability of AL09-71 N+R to invade catfish gill cells was significantly (P<0.05) lower than that of AL09-71. To understand whether target site mutation might play a role in antibiotic resistance, novobiocin's target site DNA gyrase subunit B gyrB and rifampicin's target site RNA polymerase subunit B rpoB were sequenced from the two strains. Our results revealed the following five mutations: (1) two missense mutations (CGC to ATC resulting in arginine/R to serine/S; TAC to TGC resulting in tyrosine/Y to cysteine/C) between AL09-71 gyrB and AL09-71 N+R gyrB; (2) three missense mutations (GAC to AAC resulting in aspartic acid/D to asparagine/N; CTG to CCG resulting in leucine/L to proline/P; CTG to CCG resulting in leucine/L to proline/P) between AL09-71 rpoB and AL09-71 N+R rpoB. To determine whether any unique DNA sequences were present in AL09-71 but absent in AL09-71 N+R, PCR-select bacterial genome subtractive hybridization was performed. Of 96 clones selected from the subtractive genomic DNA library, 32 sequences were found. None of the 32 sequences was confirmed to be present in AL09-71 but absent in AL09-71 N+R. At the transcription level, 29 of the 32 genes were found to be expressed greater than 10-fold in AL09-71 N+R compared to that in AL09-71.
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Affiliation(s)
- Julia W Pridgeon
- Aquatic Animal Health Research Unit, USDA-ARS, 990 Wire Road, Auburn, AL 36830, USA.
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Beck BH, Farmer BD, Straus DL, Li C, Peatman E. Putative roles for a rhamnose binding lectin in Flavobacterium columnare pathogenesis in channel catfish Ictalurus punctatus. FISH & SHELLFISH IMMUNOLOGY 2012; 33:1008-1015. [PMID: 22960031 DOI: 10.1016/j.fsi.2012.08.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 08/06/2012] [Accepted: 08/17/2012] [Indexed: 06/01/2023]
Abstract
Columnaris disease, caused by the bacterial pathogen Flavobacterium columnare, continues to be a major problem worldwide and commonly leads to tremendous losses of both wild and cultured freshwater fish, particularly in intensively farmed aquaculture species such as channel catfish. Despite its ecologic and economic impacts, the fundamental molecular mechanisms of the host immune response to this pathogen remain unclear. While F. columnare can induce marked pathologic changes in numerous ectopic tissues, the adhesion of F. columnare to the gill in particular is strongly associated with pathogen virulence and host susceptibility. Recently, in this regard, using RNA-seq expression profiling we found that a rhamnose-binding lectin (RBL) was dramatically upregulated in the gill of fish infected with F. columnare (as compared to naïve fish). Thus, in the present study we sought to further characterize and understand the RBL response in channel catfish (Ictalurus punctatus). We first identified two distinct catfish families with differential susceptibilities to columnaris disease; one family was found to be completely resistant while the other was susceptible (0% mortality versus 18.3% respectively, P < 0.001). Exclusively, in the susceptible family, we observed an acute and robust upregulation in catfish RBL that persisted for at least 24 h (P < 0.05). To elucidate whether RBL play a more direct role in columnaris pathogenesis, we exposed channel catfish to different doses of the putative RBL ligands l-rhamnose and d-galactose, and found that these sugars, protected channel catfish against columnaris disease, likely through competition with F. columnare binding of host RBL. Finally, we examined the role of nutritional status on RBL regulation and found that RBL expression was upregulated (>120-fold; P < 0.05) in fish fasted for 7 d (as compared to fish fed to satiation daily), yet expression levels returned to those of satiated fish within 4 h after re-feeding. Collectively, these findings highlight putative roles for RBL in the context of columnaris disease and reveal new aspects linking RBL regulation to feed availability.
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Affiliation(s)
- Benjamin H Beck
- United States Department of Agriculture, Agricultural Research Service, Stuttgart National Aquaculture Research Center, Stuttgart, AR, USA
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Pridgeon JW, Yildirim-Aksoy M, Klesius PH, Srivastava KK, Reddy PG. Attenuation of a virulent Aeromonas hydrophila with novobiocin and pathogenic characterization of the novobiocin-resistant strain. J Appl Microbiol 2012; 113:1319-28. [PMID: 22897434 DOI: 10.1111/j.1365-2672.2012.05430.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Revised: 07/24/2012] [Accepted: 07/25/2012] [Indexed: 12/20/2022]
Abstract
AIM To determine whether novobiocin resistance strategy could be used to attenuate a virulent Aeromonas hydrophila AH11P strain and to characterize the growth and pathogenic differences between the novobiocin-resistant strain and its virulent parent strain AH11P. METHODS AND RESULTS A novobiocin-resistant strain AH11NOVO was obtained from a virulent Aer. hydrophila strain AH11P through selection of resistance to novobiocin. AH11NOVO was found to be avirulent to channel catfish (Ictalurus punctatus), whereas AH11P was virulent. When AH11NOVO vaccinated channel catfish were challenged with AH11P at 14 days postvaccination, relative per cent of survival of vaccinated fish was 100%. The cell proliferation rate of AH11NOVO was found to be significantly (P < 0.05) less than that of AH11P. In vitro motility assay revealed that AH11NOVO was nonmotile, whereas AH11P was motile. AH11NOVO had significantly (P < 0.05) lower in vitro chemotactic response to catfish mucus than that of AH11P. Although the ability of AH11NOVO to attach catfish gill cells was similar to that of AH11P, the ability of AH11NOVO to invade catfish gill cells was significantly (P < 0.05) lower than that of AH11P. CONCLUSIONS The novobiocin-resistant AH11NOVO is attenuated and different from its parent AH11P in pathogenicity. SIGNIFICANCE AND IMPACT OF THE STUDY The significantly lower chemotactic response and invasion ability of AH11NOVO compared with that of its virulent parent strain AH11P might shed light on the pathogenesis of Aer. hydrophila.
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Affiliation(s)
- J W Pridgeon
- Aquatic Animal Health Research Unit, USDA-ARS, Auburn, AL 36832, USA.
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Sun F, Peatman E, Li C, Liu S, Jiang Y, Zhou Z, Liu Z. Transcriptomic signatures of attachment, NF-κB suppression and IFN stimulation in the catfish gill following columnaris bacterial infection. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 38:169-180. [PMID: 22669032 DOI: 10.1016/j.dci.2012.05.006] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 05/23/2012] [Accepted: 05/27/2012] [Indexed: 06/01/2023]
Abstract
Outbreaks of columnaris disease (Flavobacterium columnare) are common in wild and cultured freshwater fish worldwide. Disease occurrences, particularly those caused by virulent genomovar II isolates, in aquaculture species such as channel catfish can be devastating. In contrast to other important aquaculture pathogens, little is known about host immune responses to columnaris. Adhesion of F. columnare to gill tissue has been correlated in some previous studies to virulence and host susceptibility. Here, therefore, we conducted the first transcriptomic profiling of host responses to columnaris following an experimental challenge. We utilized Illumina-based RNA-seq expression profiling to examine transcript profiles at three timepoints (4h, 24h, and 48h) in catfish gill after bath immersion infection. Enrichment and pathway analyses of the differentially expressed genes revealed several central signatures following infection. These included the dramatic upregulation of a rhamnose-binding lectin, with putative roles in bacterial attachment and aggregation, suppression of NF-κB signalling via IκBs, BCL-3, TAX1BP1, and olfactomedin 4, and strong induction of IFN-inducible responses including iNOS2b, IFI44, and VHSV genes. Fifteen differentially expressed genes with varying expression profiles by RNA-seq, were validated by QPCR (correlation coefficients 0.85-0.94, p-value <0.001). Our results highlight several putative immune pathways and individual candidate genes deserving of further investigation in the context of development of therapeutic regimens and laying the foundation for selection of resistant catfish lines against columnaris.
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Affiliation(s)
- Fanyue Sun
- The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA
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Pridgeon JW, Klesius PH, Mu X, Song L. An in vitro screening method to evaluate chemicals as potential chemotherapeutants to control Aeromonas hydrophila infection in channel catfish. J Appl Microbiol 2011; 111:114-24. [PMID: 21501349 DOI: 10.1111/j.1365-2672.2011.05030.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
AIMS To develop an in vitro screening method to be used for identifying potential effective chemotherapeutants to control Aeromonas hydrophila infections. METHODS AND RESULTS Using catfish gill cells G1B and four chemicals (hydrogen peroxide, sodium chloride, potassium permanganate and D-mannose), the feasibility of using an in vitro screening method to identify potential effective chemotherapeutants was evaluated in this study. In vitro screening results revealed that, at concentration of 100 mg l⁻¹, H₂O₂ was the only chemical tested that was able to completely abolish the attachment and invasion of Aer. hydrophila to catfish gill cells. In vivo virulence studies using live channel catfish through bath immersion confirmed that H₂O₂ was the only chemical tested that was able to significantly (P < 0·001) reduce the mortality (from 90 or 100% to 0 or 20%) caused by Aer. hydrophila infections. CONCLUSIONS The in vitro screening method using catfish gill cells G1B could be used to initially identify potential effective chemotherapeutants to control Aer. hydrophila. SIGNIFICANCE AND IMPACT OF THE STUDY An in vitro screening method using catfish gill cells to identify potential effective chemotherapeutants described here will cut cost in research compared with the method of using live fish to screen lead compounds for fish disease control.
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Affiliation(s)
- J W Pridgeon
- Aquatic Animal Health Research Unit, USDA-ARS, Auburn, AL, USA.
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