1
|
Nhinh DT, Hoa DT, Giang NTH, Van Van K, Dang LT, Crumlish M, Dong HT, Hoai TD. Synergistic infection of Edwardsiella ictaluri and Flavobacterium oreochromis in cage cultured tilapia (Oreochromis sp.). JOURNAL OF FISH DISEASES 2023; 46:1125-1136. [PMID: 37410863 DOI: 10.1111/jfd.13832] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Revised: 06/27/2023] [Accepted: 06/29/2023] [Indexed: 07/08/2023]
Abstract
Widespread distribution of a highly pathogenic Edwardsiella ictaluri strain in farmed tilapia in northern Vietnam has recently been reported. The subsequent investigation noticed a disease outbreak occurred at five nearby tilapia farms with floating cages, in which the clinical signs of both edwardsiellosis and columnaris diseases were observed on the same infected fish and caused 65% to 85% fish mortality. Naturally diseased fish (n = 109) were sampled from the five infected farms for bacterial identification and conducting challenge tests. The two bacteria Edwardsiella ictaluri and Flavobacterium oreochromis were identified by a combination of biochemical tests, PCR and 16SrRNA sequencing methods. Experimental challenge tests on Nile tilapia resulted in the median lethal dose (LD50 ) of E. ictaluri and F. oreochromis at 70 CFU/fish by intraperitoneal (i.p.) injection and 3.6 × 106 CFU/mL by immersion, respectively. The experimentally co-infected challenged fish exposed to LD50 doses resulted in 83% ± 6% mortality, with the infected fish exhibiting clinical signs of both edwardsiellosis and columnaris diseases, mimicking the naturally diseased fish. This finding suggests that the co-infection of E. ictaluri and F. oreochromis may interact in a synergistic manner, to enhance the overall severity of the infection and elevates the need for efficient methods to control both pathogens.
Collapse
Affiliation(s)
- Doan Thi Nhinh
- Faculty of Fisheries, Vietnam National University of Agriculture, Hanoi, Vietnam
- Research Institute for Aquaculture No 1, Bac Ninh, Vietnam
| | - Dang Thi Hoa
- Faculty of Fisheries, Vietnam National University of Agriculture, Hanoi, Vietnam
| | - Nguyen Thi Huong Giang
- Faculty of Veterinary Medicine, Vietnam National University of Agriculture, Hanoi, Vietnam
| | - Kim Van Van
- Faculty of Fisheries, Vietnam National University of Agriculture, Hanoi, Vietnam
| | - Lua Thi Dang
- Research Institute for Aquaculture No 1, Bac Ninh, Vietnam
| | - Mags Crumlish
- Institute of Aquaculture, University of Stirling, Stirling, UK
| | - Ha Thanh Dong
- Department of Food, Aquaculture and Aquatic Resources Management, Agriculture and Bioresources, School of Environment, Resources & Development (SERD), Asian Institute of Technology (AIT), Klong Luang, Thailand
| | - Truong Dinh Hoai
- Faculty of Fisheries, Vietnam National University of Agriculture, Hanoi, Vietnam
| |
Collapse
|
2
|
Gieseker CM, Gaunt PS, Hawke JP, Crosby TC, Hasbrouck NR, Gao DX, Declercq AM. Epidemiological Cutoff Values for Standard Broth Microdilution Susceptibility Testing of Flavobacterium columnare Isolated from Fishes. Microb Drug Resist 2022; 28:948-955. [PMID: 35972354 DOI: 10.1089/mdr.2022.0019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Flavobacterium columnare, the causative agent of columnaris disease in a large variety of freshwater fish, is a major problem in commercial aquaculture. A limited number of antimicrobial therapies are available to control this disease; therefore, these agents must be used judiciously. To facilitate effective monitoring for changes in susceptibility, the Clinical Laboratory Standards Institute (CLSI) has a standard broth microdilution test method specific for F. columnare. However, there are no CLSI-approved criteria (termed epidemiological cutoff values [ECVs]) to interpret results. Nevertheless, researchers have developed provisional ECVs based on testing by one laboratory. To satisfy CLSI data requirements, three laboratories used the standard method to generate additional antimicrobial susceptibility data against ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, gentamicin, oxolinic acid, oxytetracycline, sulfadimethoxine/ormetoprim, and sulfamethoxazole-trimethoprim using 109 F. columnare isolates. The new data combined with previously published data from 120 F. columnare isolates were analyzed and ECVs proposed to CLSI. Of the 10 antimicrobials, ECVs were approved for ampicillin, enrofloxacin, erythromycin, florfenicol, flumequine, oxolinic acid, and oxytetracycline, which were published in the 2020 edition of the CLSI document VET04 performance standards. These ECVs will help microbiologists categorize decreased antimicrobial susceptibility among F. columnare and will help in surveillance efforts to ensure judicious antimicrobial use.
Collapse
Affiliation(s)
- Charles M Gieseker
- Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA
| | - Patricia S Gaunt
- Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA
| | - John P Hawke
- Department of Pathobiological Sciences, School of Veterinary Medicine, Louisiana State University, Baton Rouge, Louisiana, USA
| | - Tina C Crosby
- Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA
| | - Nicholas R Hasbrouck
- Food and Drug Administration, Center for Veterinary Medicine, Office of Research, Laurel, Maryland, USA
| | - Dana X Gao
- Thad Cochran National Warmwater Aquaculture Center, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi, USA
| | - Annelies M Declercq
- Department of Animal Sciences and Aquatic Ecology, Laboratory of Aquaculture and Artemia Reference Center, Ghent University, Ghent, Belgium.,Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| |
Collapse
|
3
|
Cheng GF, Kong WG, Zhai X, Mu QJ, Dong ZR, Zhan MT, Xu Z. Molecular cloning and expression analysis of CD79a and CD79b in rainbow trout (Oncorhynchus mykiss) after bacterial, parasitic, and viral infection. FISH & SHELLFISH IMMUNOLOGY 2021; 118:385-395. [PMID: 34563671 DOI: 10.1016/j.fsi.2021.09.022] [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: 07/15/2021] [Revised: 09/16/2021] [Accepted: 09/18/2021] [Indexed: 06/13/2023]
Abstract
CD79a and CD79b heterodimers are important components that consist of B cell receptor compound, which play a crucial role in transduction activation signal of the antigen binding BCR, and B cell development and antibody production. In order to investigate the characters and potential functions of CD79a and CD79b in rainbow trout (Oncorhynchus mykiss), we firstly cloned and analyzed the expression of CD79a and CD79b and found that the cDNA sequences of CD79a and CD79b both contained open reading frame of 711 and 645 bp in length for encoding the protein of 237 and 215 amino acid residues, respectively. The predicted amino acid sequences from trout were highly conserved with those of other teleost fishes in structure. Phylogenetic tree was constructed to analyze the evolutionary relationship between the trout and other known species, the result indicated that CD79a and CD79b of trout clustered at high bootstrap values with Salmo salar. Moreover, three trout infection models with F. columnare G4, I. multifiliis and infectious hematopoietic necrosis virus (IHNV) were constructed, which resulted in morphological changes and serious lesions in skin and gills. Importantly, the high expression of CD79a and CD79b occurred in skin, gills, and followed by head kidney in response to bacterial, parasitic, and viral infection, as its expression was closely related to that of Igs. Our findings indicated that CD79a and CD79b play vital roles in both systemic and mucosal immune responses of rainbow trout during bacterial, parasitic, and viral infection, which will contribute to explore the roles of CD79 subunits in B cell signaling during ontogeny and disease.
Collapse
Affiliation(s)
- Gao-Feng Cheng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Wei-Guang Kong
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China
| | - Xue Zhai
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Qing-Jiang Mu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhao-Ran Dong
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Meng-Ting Zhan
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, Hubei, 430070, China
| | - Zhen Xu
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei, 430072, China.
| |
Collapse
|
4
|
Lange MD, Abernathy J, Farmer BD, Beck BH. Use of an immersion adjuvant with a Flavobacterium columnare recombinant protein vaccine in channel catfish. FISH & SHELLFISH IMMUNOLOGY 2021; 117:136-139. [PMID: 34339820 DOI: 10.1016/j.fsi.2021.07.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 06/15/2021] [Accepted: 07/30/2021] [Indexed: 06/13/2023]
Affiliation(s)
- Miles D Lange
- United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, Auburn, AL, USA.
| | - Jason Abernathy
- 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
| | - Benjamin H Beck
- United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, Auburn, AL, USA
| |
Collapse
|
5
|
Glochidial infection by the endangered Margaritifera margaritifera (Mollusca) increased survival of salmonid host (Pisces) during experimental Flavobacterium disease outbreak. Parasitol Res 2021; 120:3487-3496. [PMID: 34427787 PMCID: PMC8460588 DOI: 10.1007/s00436-021-07285-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 08/09/2021] [Indexed: 11/24/2022]
Abstract
Co-infections are common in host-parasite interactions, but studies about their impact on the virulence of parasites/diseases are still scarce. The present study compared mortality induced by a fatal bacterial pathogen, Flavobacterium columnare between brown trout infected with glochidia from the endangered freshwater pearl mussel, Margaritifera margaritifera, and uninfected control fish during the parasitic period and after the parasitic period (i.e. glochidia detached) in a laboratory experiment. We hypothesised that glochidial infection would increase host susceptibility to and/or pathogenicity of the bacterial infection. We found that the highly virulent strain of F. columnare caused an intense disease outbreak, with mortality reaching 100% within 29 h. Opposite to the study hypothesis, both fresh ongoing and past infection (14 months post-infection) with glochidia prolonged the fish host’s survival statistically significantly by 1 h compared to the control fish (two-way ANOVA: fresh-infection, F1, 82 = 7.144, p = 0.009 and post-infection, F1, 51 = 4.227, p = 0.044). Furthermore, fish survival time increased with glochidia abundance (MLR: post-infection, t = 2.103, p = 0.045). The mechanism could be connected to an enhanced non-specific immunity or changed gill structure of the fish, as F. columnare enters the fish body mainly via the gills, which is also the glochidia’s attachment site. The results increase current knowledge about the interactions between freshwater mussels and their (commercially important) fish hosts and fish pathogens and also emphasise the importance of (unknown) ecosystem services (e.g., protection against pathogens) potentially associated with imperilled freshwater mussels.
Collapse
|
6
|
Declercq AM, Tilleman L, Gansemans Y, De Witte C, Haesebrouck F, Van Nieuwerburgh F, Smet A, Decostere A. Comparative genomics of Flavobacterium columnare unveils novel insights in virulence and antimicrobial resistance mechanisms. Vet Res 2021; 52:18. [PMID: 33579339 PMCID: PMC7881675 DOI: 10.1186/s13567-021-00899-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 01/18/2021] [Indexed: 11/28/2022] Open
Abstract
This study reports the comparative analyses of four Flavobacterium columnare isolates that have different virulence and antimicrobial resistance patterns. The main research goal was to reveal new insights into possible virulence genes by comparing the genomes of bacterial isolates that could induce tissue damage and mortality versus the genome of a non-virulent isolate. The results indicated that only the genomes of the virulent isolates possessed unique genes encoding amongst others a methyl-accepting chemotaxis protein possibly involved in the initial colonization of tissue, and several VgrG proteins engaged in interbacterial competition. Furthermore, comparisons of genes unique for the genomes of the highly virulent (HV) carp and trout isolates versus the, respectively, low and non-virulent carp and trout isolates were performed. An important part of the identified unique virulence genes of the HV-trout isolate was located in one particular gene region identified as a genomic island. This region contained araC and nodT genes, both linked to pathogenic and multidrug-resistance, and a luxR-gene, functional in bacterial cell-to-cell communication. Furthermore, the genome of the HV-trout isolate possessed unique sugar-transferases possibly important in bacterial adhesion. The second research goal was to obtain insights into the genetic basis of acquired antimicrobial resistance. Several point-mutations were discovered in gyrase-genes of an isolate showing phenotypic resistance towards first and second-generation quinolones, which were absent in isolates susceptible to quinolones. Tetracycline-resistance gene tetA was found in an isolate displaying acquired phenotypic resistance towards oxytetracycline. Although not localized on a prophage, several flanking genes were indicative of the gene’s mobile character.
Collapse
Affiliation(s)
- Annelies Maria Declercq
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium. .,Flanders Marine Institute, Wandelaarkaai 7, 8400, Ostend, Belgium. .,Laboratory of Aquaculture & Artemia Reference Center, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000, Ghent, Belgium.
| | - Laurentijn Tilleman
- Laboratory of Pharmaceutical Biotechnology, Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Yannick Gansemans
- Laboratory of Pharmaceutical Biotechnology, Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Chloë De Witte
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| | - Filip Van Nieuwerburgh
- Laboratory of Pharmaceutical Biotechnology, Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium
| | - Annemieke Smet
- Laboratory Experimental Medicine and Pediatrics, Faculty of Medicine and Health Sciences, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Annemie Decostere
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, 9820, Merelbeke, Belgium
| |
Collapse
|
7
|
Dong F, Yin GM, Meng KF, Xu HY, Liu X, Wang QC, Xu Z. IgT Plays a Predominant Role in the Antibacterial Immunity of Rainbow Trout Olfactory Organs. Front Immunol 2020; 11:583740. [PMID: 33304348 PMCID: PMC7701277 DOI: 10.3389/fimmu.2020.583740] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Accepted: 10/19/2020] [Indexed: 11/30/2022] Open
Abstract
The olfactory organs (OOs) of vertebrates play important roles in their extraordinary chemosensory capacity, a process during which they are continuously exposed to environmental pathogens. Nasopharynx-associated lymphoid tissue (NALT) contains B cells and immunoglobulins (Igs), which function as the first defense line against antigens in mammals and also exist in teleosts. However, the immune responses of teleost NALT B cells and Igs during bacterial infection remain largely uncharacterized. In this study, rainbow trout were infected with Flavobacterium columnare via continuous immersion, after which the adaptive immune responses within NALT were evaluated. F. columnare could invade trout nasal mucosa and cause histopathological changes in trout OO. Moreover, the accumulation of IgT+ B cells in trout nasal mucosa was induced by bacterial challenge, which was accompanied by strong bacteria-specific IgT responses in the nasal mucus. Importantly, our study is the first to report local nasal-specific immune responses in teleosts during bacterial challenge by characterizing the local proliferation of IgT+ B cells and generation of bacteria-specific IgT in trout OOs after F. columnare infection. In addition to the strong IgT and IgT+ B cells responses in OO, bacteria-specific IgT and IgM were also detected in serum following bacterial challenge. Taken together, our findings suggest that IgT functions as an important mucosal Ig in teleost NALT and mediates local adaptive immunity during bacterial infection, which is similar to their protective role during parasitic infection.
Collapse
Affiliation(s)
- Fen Dong
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Guang-mei Yin
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Kai-feng Meng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Hao-yue Xu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Xia Liu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Qing-chao Wang
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Zhen Xu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- Key Laboratory of Marine Biotechnology of Fujian Province, Institute of Oceanology, Fujian Agriculture and Forestry University, Fuzhou, China
| |
Collapse
|
8
|
Xu HY, Dong F, Zhai X, Meng KF, Han GK, Cheng GF, Wu ZB, Li N, Xu Z. Mediation of Mucosal Immunoglobulins in Buccal Cavity of Teleost in Antibacterial Immunity. Front Immunol 2020; 11:562795. [PMID: 33072100 PMCID: PMC7539626 DOI: 10.3389/fimmu.2020.562795] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 08/31/2020] [Indexed: 02/05/2023] Open
Abstract
The buccal mucosa (BM) of vertebrates is a critical mucosal barrier constantly exposed to rich and diverse pathogens from air, water, and food. While mammals are known to contain a mucosal associated lymphoid tissue (MALT) in the buccal cavity which induces B-cells and immunoglobulins (Igs) responses against bacterial pathogens, however, very little is known about the evolutionary roles of buccal MALT in immune defense. Here we developed a bath infection model that rainbow trout experimentally exposed to Flavobacterium columnare (F. columnare), which is well known as a mucosal pathogen. Using this model, we provided the first evidence for the process of bacterial invasion in the fish BM. Moreover, strong pathogen-specific IgT responses and accumulation of IgT+ B-cells were induced in the buccal mucus and BM of infected trout with F. columnare. In contrast, specific IgM responses were for the most part detected in the fish serum. More specifically, we showed that the local proliferation of IgT+ B-cells and production of pathogen-specific IgT within the BM upon bacterial infection. Overall, our findings represent the first demonstration that IgT is the main Ig isotype specialized for buccal immune responses against bacterial infection in a non-tetrapod species.
Collapse
Affiliation(s)
- Hao-Yue Xu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Fen Dong
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Xue Zhai
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Kai-Feng Meng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Guang-Kun Han
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Gao-Feng Cheng
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Zheng-Ben Wu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China
| | - Nan Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Zhen Xu
- Department of Aquatic Animal Medicine, College of Fisheries, Huazhong Agricultural University, Wuhan, China.,Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| |
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
Pradhan PK, Paria A, Pande V, Verma DK, Arya P, Rathore G, Sood N. Expression of immune genes in Indian major carp, Catla catla challenged with Flavobacterium columnare. FISH & SHELLFISH IMMUNOLOGY 2019; 94:599-606. [PMID: 31542493 DOI: 10.1016/j.fsi.2019.09.052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Revised: 09/14/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
Columnaris disease, caused by Flavobacterium columnare, is one of the important bacterial diseases responsible for large-scale mortalities in numerous freshwater fishes globally. This disease can cause up to 100% mortality within 24 h of infection and is considered to be a cause of concern for aquaculture industry. Despite being a serious disease, scarce information is available regarding host-pathogen interaction, particularly the modulation of different immune genes in response to F. columnare infection. Therefore, in the present study, an attempt has been made to study expression of important immune regulatory genes, namely IL-1β, iNOS, INF-γ, IL-10, TGF-β, C3, MHC-I and MHC-II in gills and kidney of Catla catla following experimental infection with F. columnare. The expression analysis of immune genes revealed that transcript levels of IL-1β, iNOS, IL-10, TGF-β, C3 and MHC-I were significantly up-regulated (p < 0.05) in both the organs of the infected catla. IFN-γ and MHC-II were up-regulated in gills of infected catla whereas, both the genes showed down-regulation in kidney. The results indicate that important immune genes of C. catla are modulated following infection with F. columnare. The knowledge thus generated will strengthen the understanding of molecular pathogenesis of F. columnare in Indian major carp C. catla.
Collapse
Affiliation(s)
- P K Pradhan
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India.
| | - Anutosh Paria
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India
| | - Veena Pande
- Department of Biotechnology, Kumaun University, Nainital, 263136, Uttarakhand, India
| | - Dev K Verma
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India
| | - P Arya
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India
| | - G Rathore
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India
| | - N Sood
- ICAR-National Bureau of Fish Genetic Resources, Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, Uttar Pradesh, India.
| |
Collapse
|
11
|
Branchial bioenergetics dysfunction as a relevant pathophysiological mechanism in freshwater silver catfish (Rhamdia quelen) experimentally infected with Flavobacterium columnare. Microb Pathog 2019; 138:103817. [PMID: 31672529 DOI: 10.1016/j.micpath.2019.103817] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/21/2019] [Accepted: 10/21/2019] [Indexed: 01/20/2023]
Abstract
Flavobacterium columnare, the causative agent of columnaris disease, is a serious bacterial disease responsible for causing devastating mortality rates in several species of freshwater fish, leading to severe economic losses in the aquaculture industry. Notwithstanding the enormous impacts this disease can have, very little is known regarding the interaction between the host and bacterium in terms of the mortality rate of silver catfish (Rhamdia quelen), as well its linkage to gill energetic homeostasis. Therefore, we conducted independent experiments to evaluate the mortality rates caused by F. columnare in silver catfish, as well as whether columnaris disease impairs the enzymes of the phosphoryl transfer network in gills of silver catfish and the pathways involved in this inhibition. Experiment I revealed that clinical signs started to appear 72 h post-infection (hpi), manifesting as lethargy, skin necrosis, fin erosion and gill discoloration. Silver catfish began to die at 96 hpi, and 100% mortality was observed at 120 hpi. Experiment II revealed that creatine kinase (CK, cytosolic and mitochondrial) and pyruvate kinase (PK) activities were inhibited in silver catfish experimentally infected with F. columnare, while no significant difference was observed between experimental and control groups with respect to adenylate kinase activity. Activity of the branchial sodium-potassium pump (Na+, K+-ATPase) was inhibited while reactive oxygen species (ROS) and lipid peroxidation levels were higher in silver catfish experimentally infected with F. columnare than in the control group at 72 hpi. Based on these data, the impairment of CK activity elicited by F. columnare caused a disruption in branchial energetic balance, possibly reducing ATP availability in the gills and provoking impairment of Na+, K +ATPase activity. The inhibition of CK and PK activities appears to be mediated by ROS overproduction and lipid peroxidation, both of which contribute to disease pathogenesis associated with branchial tissue.
Collapse
|
12
|
Magray AR, Lone SA, Ganai BA, Ahmad F, Dar GJ, Dar JS, Rehman S. Comprehensive, classical and molecular characterization methods of Saprolegnia (Oomycota; Stramnipila), an important fungal pathogen of fish. FUNGAL BIOL REV 2019. [DOI: 10.1016/j.fbr.2018.12.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
13
|
Declercq AM, Cai W, Naranjo E, Thongda W, Eeckhaut V, Bauwens E, Arias C, De La Fuente L, Beck BH, Lange MD, Peatman E, Haesebrouck F, Aerts J, Decostere A. Evidence that the stress hormone cortisol regulates biofilm formation differently among Flavobacterium columnare isolates. Vet Res 2019; 50:24. [PMID: 30971289 PMCID: PMC6458827 DOI: 10.1186/s13567-019-0641-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 02/24/2019] [Indexed: 12/19/2022] Open
Abstract
The impact of cortisol on Flavobacterium columnare biofilm formation was explored. Firstly, the dynamics of biofilm formation by one highly (HV) and one low virulent (LV) F. columnare isolate with and without the stress hormone cortisol under microfluidic flow conditions was characterized. This to confirm that F. columnare cells could form biofilm under cortisol supplementation, and to compare the temporal and structural differences between different treatment groups. One trial revealed that in both isolates cell aggregates resembling biofilms occurred within 7-h post-inoculation. Consequently, cell clusters were sloughed away, followed by a rebuilding of bacterial cell aggregates, suggestive for a high spreading capacity. While the HV isolate revealed cell aggregates formed upstream at all time-points, for the LV isolate this was only seen upon cortisol supplementation. Secondly, the transcriptional effect of genes (gldK, gldL, gldM, gldN, sprA, sprE, sprT, and porV) belonging to the Type IX secretion system involved in gliding motility was investigated in planktonic and biofilm cells of a HV and LV isolate to which no, a low (LD) or high (HD) dose of cortisol was added. Significantly lower expression of gliding genes gldK, gldL, gldM and gldN, and of protein secretion regulator porV was seen in the LV isolate planktonic cells supplemented with a HD-cortisol. The LV isolate biofilm cells treated with the HD-cortisol showed a significant upregulation of sprT, encoding mobile surface adhesion important in bacterial colonization. This is the first evidence for the co-regulatory effect of cortisol on biofilm formation and F. columnare gliding gene expression.
Collapse
Affiliation(s)
- Annelies Maria Declercq
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, 9000, Belgium. .,Stress Physiology Research Group, Faculty of Pharmaceutical Sciences, Ghent University, Ostend, 8400, Belgium.
| | - Wenlong Cai
- School of Fisheries, Aquaculture, and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, 36849, USA
| | - Eber Naranjo
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA
| | - Wilawan Thongda
- School of Fisheries, Aquaculture, and Aquatic Sciences, Aquatic Genetics and Genomics, Auburn University, Auburn, AL, 36849, USA
| | - Venessa Eeckhaut
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, 9000, Belgium
| | - Eva Bauwens
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, 9000, Belgium
| | - Covadonga Arias
- School of Fisheries, Aquaculture, and Aquatic Sciences, Aquatic Microbiology Laboratory, Auburn University, Auburn, AL, 36849, USA
| | - Leonardo De La Fuente
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA
| | - Benjamin H Beck
- United States Department of Agriculture, Agricultural Research Service, Aquatic Animal Health Research Unit, Auburn, AL, 36849, USA
| | - Miles D Lange
- United States Department of Agriculture, Agricultural Research Service, Harry K. Dupree Stuttgart National Aquaculture Research Center, Stuttgart, AR, 72160, USA
| | - Eric Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences, Aquatic Genetics and Genomics, Auburn University, Auburn, AL, 36849, USA
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, 9000, Belgium
| | - Johan Aerts
- Stress Physiology Research Group, Faculty of Pharmaceutical Sciences, Ghent University, Ostend, 8400, Belgium.,Stress Physiology Research Group, Animal Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food, Ostend, 8400, Belgium
| | - Annemie Decostere
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, 9000, Belgium
| |
Collapse
|
14
|
|
15
|
Lange MD, Farmer BD, Declercq AM, Peatman E, Decostere A, Beck BH. Sickeningly Sweet: L-rhamnose stimulates Flavobacterium columnare biofilm formation and virulence. JOURNAL OF FISH DISEASES 2017; 40:1613-1624. [PMID: 28581211 DOI: 10.1111/jfd.12629] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/07/2017] [Accepted: 02/09/2017] [Indexed: 06/07/2023]
Abstract
Flavobacterium columnare, the causative agent of columnaris disease, causes substantial mortality worldwide in numerous freshwater finfish species. Due to its global significance and impact on the aquaculture industry continual efforts to better understand basic mechanisms that contribute to disease are urgently needed. The current work sought to evaluate the effect of L-rhamnose on the growth characteristics of F. columnare. While we initially did not observe any key changes during the total growth of F. columnare isolates tested when treated with L-rhamnose, it soon became apparent that the difference lies in the ability of this carbohydrate to facilitate the formation of biofilms. The addition of different concentrations of L-rhamnose consistently promoted the development of biofilms among different F. columnare isolates; however, it does not appear to be sufficient as a sole carbon source for biofilm growth. Our data also suggest that iron acquisition machinery is required for biofilm development. Finally, the addition of different concentrations of L-rhamnose to F. columnare prior to a laboratory challenge increased mortality rates in channel catfish (Ictalurus punctatus) as compared to controls. These results provide further evidence that biofilm formation is an integral virulence factor in the initiation of disease in fish.
Collapse
Affiliation(s)
- M D Lange
- Harry K. Dupree Stuttgart National Aquaculture Research Center, U.S. Department of Agriculture, Agricultural Research Service, Stuttgart, AR, USA
| | - B D Farmer
- Harry K. Dupree Stuttgart National Aquaculture Research Center, U.S. Department of Agriculture, Agricultural Research Service, Stuttgart, AR, USA
| | - A M Declercq
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
- Stress Physiology Research Group, Department of Bio-analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ghent, Belgium
| | - E Peatman
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, USA
| | - A Decostere
- Department of Pathology, Bacteriology and Poultry Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - B H Beck
- Aquatic Animal Health Research Unit, U.S. Department of Agriculture, Agricultural Research Service, Auburn, AL, USA
| |
Collapse
|
16
|
Zeng YY, Feng L, Jiang WD, Liu Y, Wu P, Jiang J, Kuang SY, Tang L, Tang WN, Zhang YA, Zhou XQ. Dietary alpha-linolenic acid/linoleic acid ratios modulate immune response, physical barrier and related signaling molecules mRNA expression in the gills of juvenile grass carp (Ctenopharyngodon idella). FISH & SHELLFISH IMMUNOLOGY 2017; 62:1-12. [PMID: 28063950 DOI: 10.1016/j.fsi.2017.01.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 12/29/2016] [Accepted: 01/03/2017] [Indexed: 06/06/2023]
Abstract
This study was conducted to explore the possible effects of dietary ALA/LNA ratios on the gill immunity, tight junction and antioxidant capacity, and the related signaling factor mRNA levels of juvenile grass carp (Ctenopharyngodon idella). Fish were fed diets with different ALA/LNA ratios (0.01, 0.34, 0.68, 1.03, 1.41, 1.76 and 2.15) for 60 days. The present results showed that ALA/LNA ratio of 1.03 significantly enhanced lysozyme and acid phosphatase activities, complement 3 contents, promoted mRNA levels of antimicrobial peptides (Hepcidin and liver expression antimicrobial peptide-2), anti-inflammatory cytokines (interleukin 10 and transforming growth factor β1) and inhibitor protein κBα, whereas suppressed pro-inflammatory cytokines (interleukin 1β, interleukin 8, tumor necrosis factor a and interferon γ2), and signal molecules (IκB kinase β, IκB kines γ and nuclear factor κB p65) mRNA levels in the gill, indicating that optimal dietary ALA/LNA ratio improve gill immunity of juvenile fish. Besides, ALA/LNA ratio of 1.03 increased mRNA levels of the barrier functional proteins (occludin, zonula occludens-1, claudin-b, -c and -3), and reduced the pore-formation proteins (claudin-15a) and myosin light-chain kinase mRNA abundance in the gill of juvenile grass carp, indicating optimum ALA/LNA ratio strengthen gill tight junction of juvenile fish. Additionally, ALA/LNA ratio of 1.03 increased glutathione contents, copper/zinc superoxide dismutase, glutathione peroxidase, glutathione S-transferase and glutathione reductase activities and mRNA abundance, and nuclear factor erythoid 2-related factor 2 mRNA levels in the gill of fish, suggesting that optimal ALA/LNA ratio ameliorate gill antioxidant status of juvenile fish. Interestingly, dietary ALA/LNA ratios had no effect on IκB kinase α and catalase activities in fish gills. Collectively, optimal dietary ALA/LNA ratio could improve gill immunity and strengthen physical barrier of juvenile fish. Based on the quadratic regression analysis of complement 3 content in the gill, optimal dietary ALA/LNA ratio for maximum growth of juvenile grass carp was estimated to be 1.12.
Collapse
Affiliation(s)
- Yun-Yun Zeng
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China
| | - Lin Feng
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China
| | - Wei-Dan Jiang
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China
| | - Yang Liu
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China
| | - Pei Wu
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China
| | - Jun Jiang
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China
| | - Sheng-Yao Kuang
- Animal Nutrition Institute, Sichuan Academy of Animal Science, Chengdu 610066, China
| | - Ling Tang
- Animal Nutrition Institute, Sichuan Academy of Animal Science, Chengdu 610066, China
| | - Wu-Neng Tang
- Animal Nutrition Institute, Sichuan Academy of Animal Science, Chengdu 610066, China
| | - Yong-An Zhang
- Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Xiao-Qiu Zhou
- Animal Nutrition Institute, Sichuan Agricultural University, Chengdu 611130, China; Fish Nutrition and Safety Production University Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu 611130, China; Key Laboratory for Animal Disease-Resistance Nutrition of China Ministry of Education, Sichuan Agricultural University, Chengdu 611130, China.
| |
Collapse
|
17
|
Cortisol directly impacts Flavobacterium columnare in vitro growth characteristics. Vet Res 2016; 47:84. [PMID: 27530746 PMCID: PMC4987970 DOI: 10.1186/s13567-016-0370-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 07/08/2016] [Indexed: 11/18/2022] Open
Abstract
Teleost fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal axis to release glucocorticoids, in particular cortisol, into the blood. For the majority of bacterial fish pathogens, stress is considered a key factor in disease outbreaks. Based upon studies in mammals, there is considerable evidence to suggest that, besides impairing the immune system, cortisol can have a direct effect on bacterial cells. Hitherto, this intriguing field of microbial endocrinology has remained largely unexplored in aquatic diseases. The present study investigated in vitro the impact of cortisol on phenotypic traits of the fresh water fish pathogen Flavobacterium columnare. Colonies obtained from the highly virulent (HV) isolates resulted in significantly larger and more spreading colonies compared to those from the low virulent (LV) isolates. High cortisol doses added displayed a direct effect on the bacterial cells and induced a significant decrease in colony size. An additional intriguing finding was the inverse relationship between cortisol concentrations added to the broth and the spreading character of colonies retrieved, with higher cortisol doses resulting in less rhizoid to rough and even smooth colony formation (the latter only in the LV trout isolate), suggesting a dose–response effect. The loss of the rhizoid appearance of the F. columnare colonies upon administration of cortisol, and hence the loss of motility, might indicate a phenotypic change to the biofilm state. These findings form the basis for further research on the impact of glucocorticoids on other virulence factors and biofilm formation of F. columnare.
Collapse
|
18
|
Declercq AM, Chiers K, Van den Broeck W, Dewulf J, Eeckhaut V, Cornelissen M, Bossier P, Haesebrouck F, Decostere A. Interactions of highly and low virulent Flavobacterium columnare isolates with gill tissue in carp and rainbow trout. Vet Res 2015; 46:25. [PMID: 25889257 PMCID: PMC4350652 DOI: 10.1186/s13567-015-0164-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 02/16/2015] [Indexed: 12/24/2022] Open
Abstract
The interactions of Flavobacterium columnare isolates of different virulence with the gills of carp (Cyprinus carpio L.) and rainbow trout (Oncorhynchus mykiss Walbaum) were investigated. Both fish species were exposed to different high (HV) or low virulence (LV) isolates and sacrificed at seven predetermined times post-challenge. Histopathological and ultrastructural examination of carp and rainbow trout inoculated with the HV-isolate disclosed bacterial invasion and concomitant destruction of the gill tissue, gradually spreading from the filament tips towards the base, with outer membrane vesicles surrounding most bacterial cells. In carp, 5-10% of the fish inoculated with the LV-isolate became moribund and their gill tissue displayed the same features as described for the HV-isolate, albeit to a lesser degree. The bacterial numbers retrieved from the gill tissue were significantly higher for HV- compared to LV-isolate challenged carp and rainbow trout. TUNEL-stained and caspase-3-immunostained gill sections demonstrated significantly higher apoptotic cell counts in carp and rainbow trout challenged with the HV-isolate compared to control animals. Periodic acid-Schiff/alcian blue staining demonstrated a significantly higher total gill goblet cell count for HV- and LV-isolate challenged compared to control carp. Moreover, bacterial clusters were embedded in a neutral matrix while being encased by acid mucins, resembling biofilm formation. Eosinophilic granular cell counts were significantly higher in the HV-isolate compared to LV-isolate inoculated and control carp. The present data indicate a high colonization capacity, and the destructive and apoptotic-promoting features of the HV-isolate, and point towards important dynamic host mucin–F. columnare interactions warranting further research.
Collapse
Affiliation(s)
- Annelies Maria Declercq
- Department Morphology, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Koen Chiers
- Department of Pathology, Bacteriology and Poultry diseases, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Wim Van den Broeck
- Department Morphology, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Jeroen Dewulf
- Department of Reproduction, Obstetrics and Herd Health, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Venessa Eeckhaut
- Department of Pathology, Bacteriology and Poultry diseases, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Maria Cornelissen
- Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, De Pintelaan 185, 9000, Ghent, Belgium.
| | - Peter Bossier
- Ghent University, Laboratory of Aquaculture and Artemia Reference Center, Rozier 44, 9000, Ghent, Belgium.
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Poultry diseases, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| | - Annemie Decostere
- Department Morphology, Ghent University, Faculty of Veterinary Medicine, Salisburylaan 133, 9820, Merelbeke, Belgium.
| |
Collapse
|